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Title: Cork: Its Origin and Industrial Uses
Author: Stecher, Gilbert E.
Language: English
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  [Illustration: GATHERING CORKWOOD]

  Its Origin and Industrial Uses







This monograph is not an attempt to put before the reading public a
scientific exposition of the merits and qualities of the Quercus Suber
or Quercus Liber (Linnæus), and carry it up into the heights of learning
where none but the learned may go; but to set forth in as concise a
manner as possible, the plain story of the corkwood stopper so well
known to all. The corkwood as seen in the stopper and in many other
articles of trade, has long been of service to man, and remained
unnoticed in journals of science, but for a word here and there—and in
trying to acquaint myself with its generalities, found it most difficult
to get even these. This rather impressed me as being singular, a
material so largely used and so little to its credit, in literature,
that I pressed my investigations only to find that the farther I
searched the less I found.

The few facts gleaned were of interest, and it occurred to me to put
them together in some readable form, for future reference. But as I
reflected upon the unsuccessful attempt to get information, which was
made in behalf of my studies, I promptly decided to go into the subject
deep enough to cover all the facts and the result is this
monograph—Quercus Suber—

It is presented with the hope that it will help others who seek a
knowledge of corkwood and is only intended as a résumé of a very
interesting subject. I have endeavored to give credit to those to whom
it is due and offer my results as a tribute to a material that stands in
a class worthy of the scientists’ as well as the commercialists’ esteem.

  June 15, 1914.


  Quercus Suber (Cork)                      3

  Quercus Liber (Linnæus)                   5

  Cork                                      7

  Origin                                    9
    _Including the territory of growth and
    attempts to transplant the seed._

  The Tree and Growth                      12

  Diseases                                 16

  Stripping                                17

  Botany and Chemistry                     22
    _Including compression diagram._

  Uses and Application                     39

  Substitutes                              53

  Manufacture                              55
    Raw stock.
    Stopper making.
    Cork Disc making.
    Waste utilization.

  Extent of the Manufacturing Industry     71

  Appendix                                 76

  Its Origin and Industrial Uses



The material of which this monograph treats has become of double
interest because of its shrouded mystery, which has never been pierced
to the extent of giving the world a complete and comprehensive story.
The mysticism does not encompass its utility and general uses nor its
native land, as these are well known, but is more associated with its
character, composition and chemical makeup.

Its uses may be traced far back into the misty past that is dim to us,
but from the faint scroll of history looms up in the mind’s eye as an
epoch that we may have been glad to know, and although the references
are few, by carefully analyzing them we may glean somewhat of its

The arcana attending it have been revealed to a few, who no doubt,
through curiosity, have endeavored to penetrate its obscurity, but
unfortunately have not written extensively upon the subject, instead
leaving a meager memorandum of their findings. The years of its use have
given very little knowledge of it to us, the reason perhaps being the
lack of competition and therefore no necessity for a close scrutiny to
find additional qualities to recommend it above others. And an
additional mystery is that it has been in use for so many years and so
little said about it. Its latent qualities have mystified those who have
handled it for years, and from them we can learn very little; so it will
be of interest to peruse practically all that has been written,
incorporated in this treatise, with the addition of the latest
investigations upon the subject. To present this in a form which will
give credit to the small but authoritative references and place them in
their proper order, together with other recent data, was no small task,
and in presenting the total matter in concise style meant the weeding
out of all extraneous language or superfluous description.

In considering this material, it may be well to start with a few
precursory remarks as to the etymology of the words by which it has been
designated in the past and is now known, as by so doing it will convey a
better understanding of the material to follow.


The above name is the true one of the material under discussion and is
derived from the Latin. Quercus; Italian or esculent oak sacred to
Jupiter. Liber; binding or surrounding; hence surrounding of the oak or
bark of the oak, sacred to Jupiter.


This, its definite name, undoubtedly conveyed some particular meaning to
the ancients, but research fails to reveal any definition of the word
“Suber.”[1] “The word is so far a puzzle to philologists. Forcellini in
his great dictionary of Latin says that it is perhaps connected with the
Greek word (συφαρ = suphar), which means ‘an old wrinkled skin, as, for
instance, the cast-off skin of a snake.’ If this derivation be sound,
the Romans, in using the word, thought at the outset primarily of the
rough bark of the tree and then of the tree as a whole. Forcellini
quotes also an opinion of Isidorus Hispalensis upon the longer form of
‘Suber,’ i.e., Suberies, to the effect that this form is derived from
‘sus’ (swine) and ‘edo’ (eat) because swine eat the acorns. But this is
a purely popular etymology. I find too that Scaliger derived it from the
verb ‘Subio’ ‘to come up from below’ because cork will not stay down in
water. Vaniçek, in his Etymologisches Wörterbuch, classes ‘Suber’ among
the dunkel words, and in the new and most elaborate Historische
Grammatic of Stolz the word is not mentioned at all in the treatment of
roots. Even Otto Keller in his work on Etymologies has nothing to say
about it.”

  [1] Letter from Prof. Nelson G. McCrea of Columbia University, June
      12, 1910, to writer.


This name is as much of a mystery as the word “Suber” and its origin can
only be guesswork. In the opinion of the writer it is the broadening of
the first syllable of the word “Quercus” and has no bearing upon its
usage, composition or lineage. Some dictionaries give other derivations,
such as the mutilation of the Spanish “Corcho” or the French “Calk,” and
others that it is taken from the Latin Cortex,[2] meaning the outer
shell or husk, the external part, but they do not present any convincing

  [2] According to “Spanish Dictionary” of Lopes et Bensley; Cortex: “La
      Parte exterior del Arbol.” Arbol in botany meaning “a tree.”

The meaning of the word “cork” as applied to-day is derived from the
Arabic “Kalafa,” to stop the seams of ships; the Latin “Stipo,” to
suppress; the French, “Calfeutrer,” to stop. But these do not bear upon
the origin of the word “cork,” as in all probability the word was coined
independent of these sources, but as we apply the word to a definite
act, that of “stopping,” the definition as given above is applicable,
although the proper name would be “stopper,” regardless of what material
it is made. It is therefore plain that the word “cork” is a Latin
phonetic abbreviation, for it appears to be the only logical root for
the word.

The cork tree is called “Alcornoque” in Castilian language; Surn in
Castalan; Sobreiro, Gallician; Suvi y Sioure in provincialism; Chêne
Liège in French; Keonge fernam or only fernam, in Argeline; Kork-baum or
Korkeiche in German; and, as before stated, cork in English.[3]

  [3] Consul Schenck’s Report.


The study of its origin leads us to that romantic part of the world
bordering the Mediterranean Sea from which we have already received so
much in all branches. The cork-producing country practically covering
the whole of Portugal sweeping toward the East through the southern
districts known as Andalusia and Estremadura, thence northeast,
embracing thousands of acres of forests in Catalonia. Spain and Portugal
dividing honors among the nations in the annual yield of raw material,
with perhaps the advantage leaning slightly to the latter.[4] This being
partly due to increased area, no doubt, as the geographical situation is
the same but with the irrigation feature slightly in favor of Spain, as
through the corkwood country flows the Guadalquivir River in addition to
the three which also pass through Portugal, consisting of the Douro,
Tagus and Guadiana in the west, and the Ebro in the Gerona district.

  [4] Armstrong Cork Co.’s pamphlet.

Tunis and Algeria[5] rank next in importance with Southern France,
including Corsica following closely. Italy (Tuscany) too with the help
of Sardinia and Sicily continuing to be quite a factor in meeting the
demand for the crude material, while across the Strait of Gibraltar the
sun-scorched forests of Morocco at El-araish are as yet undeveloped,
although rapidly being pressed into service.

  [5] There are large forests of cork on the French Colony of Algeria,
      particularly on an estate granted by the Emperor Napoleon III to
      M. le duc de Montebello.—H. G. GLASSPOOLE.

The geographical formation of Portugal is extremely favorable for the
rearing of cork trees, every evidence of this characteristic being well
marked by the densely thick groups of cork trees to be seen in certain
regions, especially in the Valley of the Tagus and the Sierra de
Portalegre provinces of Alemtejo and Algarve, which are the chief
bearing centers of this country,[6] the area devoted to their
cultivation being approximately 366,000 hectares.

  [6] Chambers Journal.

In Spain it is found in the Provinces of Gerona, Caceres, Andalusia,
Huelvas, Seville, Cadiz, Ciudad Real, Malaga, Cordoba and Toledo in the
order named.

According to a calculation made by the administration of forests the
extent of cork forests in Spain is about 255,000 hectares,[7] viz.
80,000 in the Province of Gerona, 54,000 in Huelvas, 32,500 in Caceres,
28,000 in Seville, 20,000 in Cadiz, 11,500 in Ciudad Real and 9500 in
Cordoba. The remainder is distributed between ten other provinces.[8]

  [7] One hectare = 2.471 acres.

  [8] Consul Schenck’s Report.

In the Province of Gerona is included a large territory stretching
northward towards the Pyrenees to the Valley of the Muge and Ter. In
France, according to Consul Goldschmidt of Nantes, the cork-producing
territory is divided as follows: Var, 280 acres; Lot-et-Garonne, 27
acres; Landes, 32 acres; Corsica, 40 acres; making about 379 acres in

This résumé of the cork-producing countries of Europe will convey some
idea of the extent of the forests, and will also show the climate sort
by the tree; for it is proven that it flourishes best in an altitude of
1600 to 3000 feet, in an average mean temperature of 55° Fahrenheit; and
at points beyond 45° north latitude its successful propagation is

The Mediterranean Basin is particularly suitable for the rearing of
corkwood, and although many attempts have been made to transplant the
seed, the results have proven fatal.

Notable among these attempts being the American ambition to introduce
the tree in the United States. Portuguese acorns were brought to Wayne
County, Mississippi, and planted in 1859; the result, as far as the
growth was concerned, was splendid; but after a wait of eleven years,
the final crop was not a commercial success. Another attempt was made in
1872, in southern California, but with no better outcome than the first,
in which some of the trees attained to a height of thirteen feet (3.965
meters) and the stem, to a diameter of eleven inches (2.794 decimeters),
including the cork, which attained a thickness of one inch (2.540
centimeters). This evidently rapid growth would infer that the American
zone was all that could be desired for the favorable rearing of cork
trees; but strange to say this was not the case. Although the growth of
the tree had been exceptionally strong, the quality of its salient
product turned out to be of an inferior character. The cork generally
improves with the age of the tree; in this instance, however, even after
years of maturity the cork harvest did not improve to any great extent,
and indeed is still of a second-rate quality.[9] And Consul S. C. Reat,
writing from Tamsui, recently reports the efforts of the Japanese
Government to plant cork trees in Formosa and the Ogasawara Isles, in
the endeavor to supply small corks to the Japanese merchants, the result
of which, is yet to be learned.

  [9] _Chambers Journal._


Many botanists consider the cork oak of Europe as belonging to two
species, one chiefly characterized by annual fructification and the
persistence of the leaves for two or three years (Quercus Suber,
Linnæus); the other by biennial fructification and annual persistence of
the leaves (Quercus Occidentalis, Gay).[10]

  [10] _Garden and Forest_, Vol. VIII, 52.

In the French departments of the Landes and Gironde the Quercus
Occidentalis forms extensive woods, as also in Spain, Algeria and
in some parts of Italy, while the Quercus Suber is a native of the
Atlantic side of France and Portugal, where this tree grows to the
greatest perfection, and to which countries we are indebted for the
major part of our supply. The cork tree bears a general resemblance to
the broad-leaved kind of (Quercus Ilex, Holm) or evergreen oak, of which
species some authors consider it only a variety; but when full grown it
forms a much handsomer tree.

“In the localities to the north the cork is better than those exposed to
the south. It grows and develops in ground of very little depth, and
sometimes in ground, in appearance very stony. It is seldom found in
calcareous soil, preferring always a soil of feldspar, and like the
chestnut flourishes best in a sandy one.”[11]

  [11] Consul Schenck’s Report.

The cork-oak attains a height of from six to eighteen meters, at times
reaching fifty meters[12] and measures as much as 1.22 meters in
diameter.[13] Its branches are covered with small evergreen leaves,
which are rather spongy and velvety to the touch, have a glossy
appearance and a saw-tooth edge, measuring about three to five
centimeters[14] long and one and one-half to two wide. The roots are
strong and spread considerably, and frequently are to be seen on the
surface of the ground. The flowers or blossoms make their appearance in
May; the fruit ripens in the fall or winter, from September to January,
and falling from the tree as soon as ripe. Three qualities of acorns are
to be observed according to their time of ripening and are called,
“brevas primerizas de San Miguel,” which ripen in September; the second
or middling “Martinencas,” which ripen in October and November; and
finally the “tardias Ó palo-Meras,” which ripen in December and January.
These acorns form one of the forest’s chief sources of revenue, since
fed to swine, they give a peculiarly piquant flavor to the meat, Spanish
mountain hams being noted for their excellence.[15]

  [12] Meter = 3.28 feet.

  [13] In a cork-wood of Montenegro (municipal district of Quart,
       Province of Gerona) the property of D. Romulo Bosch, and near the
       place called La Mina, we measured in August, 1877, a tree that
       was 4.95 meters in circumference, breast high, and the trunk of
       the tree five meters high, calculating its age between one
       hundred and fifty and two hundred years old. Consul Schenck’s
       Report, 1890.

  [14] Centimeter = .3937 inch.

  [15] Consul Schenck’s Report, 1890. Authority M. Fee.

In the following paragraphs I will quote principally from Consul
Schenck’s Report, 1890, relating to the growing and procuring of the
bark for shipment, with interpolated sentences and slight changes, made
necessary by other data at hand. The most common practice is to
cultivate this plant by sowing, which is frequently done, above all, in
ground somewhat manured, making alternate furrows with vines. Up to
their twentieth or twenty-fifth year the ground is cultivated as if it
were a vineyard, rooting up at that age the vines on account of
producing less fruit, and also on account of the cork trees being pretty
well grown up and no longer requiring the shelter of the vines. At the
end of even one year it is difficult to transplant the cork tree on
account of the length of the roots, principally the central one, and if
the trees are put out with the intention of transplanting they are
generally sewn in a false ground bottom made artificially at a certain
depth with layers of stones or bricks. French silviculturists recommend
about 110 to 120 trees to the hectare (2.471 acres).

The cork tree gives but little shade, which contributes greatly in
causing the soil to become dry. To avoid all these inconveniences, which
are highly unfavorable to the good production of cork, it is requisite
that young plants grow up with sufficient foliage, so that the branches
touch each other, and even overreach, till they are about twenty-five
years old. It may be convenient, if there is not sufficient foliage from
the cork trees themselves, to introduce secondary species, such as the
elm tree, ash and pine, known as (pi meli), these being depended upon to
supply the requisite coolness and manure to the ground. If the soil is
poor, the cork is thin but of fine quality and very appropriate to make
the best stoppers. If, on the contrary, it is rich, the cork is thick
but spongy. Consequently it is requisite to treat the cork tree in such
a manner that whilst the cork grows thick it will at the same time be
fine in texture. This is of course an agricultural problem and may
differ from year to year in the necessary details.


The cork tree has in no wise escaped from disease and infections; on the
contrary it has its full allotted share which worries the growers more
than the acquiring of a perfect texture, and unless great care is taken
will greatly reduce the value of a crop. The larva of the Coroebus
undatus (corch) attacks the interior of the cork, penetrating frequently
into the tree itself, which causes an undervaluation in the quality of
the cork, and, moreover, these perforations unite so closely and in such
a manner even in the trunk of the tree that in peeling off the cork,
part of the skin of the trunk itself comes off, causing much damage to
the tree.

The larva of the Cerambyx cerdo, as well as the ant, Formica rufa L.
hormigas, destroys the fine cork with their numerous borings and
galleries. Jaspered (Jasperado) is the name by which is known one of the
defects of the cork which reduces it greatly in value and as far as
can be learned comes from the tree itself. The porosity of cork is
greatly increased by the presence of cork-meal, resulting from the
disintegration of the Sclerenchyma, or stone cells, which penetrate
the cork fiber and falling to a powder facilitate the entrance of

  [16] _Scientific American_, 1906.


[17] The corkwood or cork of commerce is the external part or “periderm”
of the cork-oak; and when it has attained a diameter of approximately
12.7 centimeters or the tree measures forty centimeters in circumference
according to the Spanish governmental regulations, which the tree does
usually by the time it is twenty years old, the bark may be removed. The
stripping generally takes place during July and August, and it is a
process which demands skill and care, if injury to the bark is to be
avoided. In Algeria the French strippers sometimes use crescent-shaped
saws, but under the usual Spanish method a hatchet, with a long handle,
is the only implement employed. The bark is cut clear through, around
the base of the tree, and a similar incision is made around the trunk,
just below the spring of the main branches; the two incisions are then
connected by one or two longitudinal cuts, following, so far as
possible, the deepest of the natural cracks in the bark. Inserting the
wedge-shaped handle, the tree’s covering is then pried off. The larger
branches are stripped in the same manner, yielding, generally, a finer
grade of cork than that of the trunk. The thickness of the bark ranges
from 1.27 centimeters to 6.85 centimeters, while the yield also varies
greatly from twenty to 75 kilograms[18] per tree, depending upon its
size and age. After the first stripping the tree is left in the
juvenescent state to regenerate, and great care must be taken in the
stripping not to injure the inner skin or epidermis at any stage of the
process, for the life of the tree depends upon its proper preservation,
for if injured at any point, growth there ceases and the spot remains
forever afterward scarred and uncovered. It is also necessary to avoid
stripping during the prevalence of a sirocco, which would dry the inner
skin too rapidly and therefore exclude all further formation of cork.

  [17] Armstrong Cork Co.’s pamphlet.

  [18] Kilogram = 2.205 pounds.

The Capgrand-Mothe system, which, as known, consists of dressing the
trunk with the same cork just removed, and leaving it so dressed for a
couple of months, has not met with approval, as being impracticable on a
large scale. After the stripping, the phellogen, the seat of the growing
processes, undertakes at once the formation of a new covering of finer
texture, and each year this, the real skin, with its life-giving sap,
forms two layers of cells, one within, increasing the diameter of the
trunk, the other without, adding thickness to the sheathing of bark.
After eight or ten years this sheathing is removed, and while more
valuable than the first stripping, it is not as fine in quality as that
of the third and subsequent strippings, which follow at regular
intervals of about nine years. At the age of about forty years the oak
begins to yield its best bark, continuing productive as a rule for
almost a century.[19] The cork of the first barking is called
Corcho-Bornio, Borniza or virgin, and is so coarse, rough, and dense in
texture that it is of little commercial value. The second barking is
called “pelas,” or secondary cork, and this and subsequent barkings
constitute the cork of commerce. As the bark is removed it is gathered
up in piles (rusque) and left for a few days to dry. Having been
weighed, it is next carried either in wagons or on the backs of burros
to the boiling station, where it is stacked and allowed to season for a
few weeks. It is then ready for the boiling process. The outside of the
bark in its natural state is, as may well be imagined, rough and woody,
owing to exposure to the weather. After boiling this useless outer
coating is readily scraped off, thereby reducing the weight of the
material almost twenty per cent. The boiling process also serves to
remove the tannic acid, increases the volume and elasticity of the bark,
renders it soft and pliable and flattens it out for convenient packing.
After being roughly sorted as to quality and thickness, the bark is then
ready for its first long journey, and as the forests are generally
located in hilly or even mountainous country, the faithful burro must
again be called into service. Truly the Spaniards’ best friend, though
the worst treated of all, these patient little animals present a most
grotesque appearance when loaded from head to hind quarters with a huge
mass of the light bark. Down from the hills they go in trains of thirty,
forty or even a hundred, threading the rocky bridle paths in single file
and wending their way through the narrow streets of quaint villages
where traces of Moorish occupancy may still be seen, to the nearest
railway station. The corkwood is there freighted to the various sea-port
warehouses in Spain and Portugal, Seville, Spain being perhaps the
largest depository and user of raw material.[20] This historic city,
situated on the banks of the Guadalquivir, presents a very animated
sight in the summer months, and plays a very important part in the cork
industry, for besides the numerous warehouses for storing and shipping
there are factories for the manipulation of cork and its conversion into
the many useful forms in which it has proven of value. Before shipping,
the bales are opened, the edges of the bark trimmed and the bark then
sorted into the various grades of quality and thickness again. The
importance of this last mentioned operation cannot be overemphasized, as
the whole problem of the successful and economical manufacture of corks
center about it. After sorting it is ready to be rebaled for shipment,
this generally being done by placing the large, flat pieces called
planks or tables, at the bottom of the bales, and above them the small
pieces which are covered in turn with larger sections; then the whole
mass being subjected to pressure to render it compact, afterward being
bound up securely with steel hoops or wires. Each bale carefully marked
indicating the grade or quality, loaded directly into ocean-going
steamers and shipped to the ports of the world.

  [19] Mr. Lamey, the author of a study upon cork in Algeria, published
       some interesting tables in this work regarding the annual
       increase and the mean thickness of cork. According to him
       cork-bark should not be removed before it has attained a
       thickness of 2.032 cm., and the formation of new cork has been
       well explained by Mr. Mathieu in his “Forestry Flora.”

  [20] Armstrong Cork Co.’s pamphlet.

From this meager description we at least can learn what “corkwood” is,
the limited sphere of its growth, the constant care necessary to insure
a successful harvest or gathering, the peculiarities of the tree, its
longevity and the general mode of preparing the bark for shipment; the
narration in no wise doing justice to this most interesting material, in
its natural state, for its growing is a fascinating tale in itself; but
for the purpose of this writing the foregoing has been deemed sufficient
to convey an understanding of it.

As we have now seen how this wonderful material grows, its haunts and
dwellings, we will look at it more closely and see what it really is,
how this particular formation comes about and its peculiarities.


In considering “cork” for the purpose of ascertaining its
characteristics, texture and composition we will, instead of analyzing
the material after it has reached the market, look at it from the
standpoint of botany and learn of its formation upon the tree, from
which it is procured. It appears that the word “cork”[21] in botany
signifies a growth peculiar to all plants and pertaining to none in
particular, being described as “a peculiar tissue in the higher plants
forming the division of the bark (which name is sometimes restricted to
the dead tissues lying outside the cork); consisting of closely packed
air-cells nearly impervious to air and water and protects the underlying
tissues.”[22] Again, “It is produced by the activity and division of
certain merismatic cells known as phellogen or cork cambium which are
situated immediately within the epidermal covering of the young growth.
As the cork cells grow older, their protoplasmic contents disappear and
are replaced by air. In order that this formation may be clearly
understood, I will quote from a paragraph entitled “Cork and Epidermal
Formations Produced by It” contained in “A Text Book on Botany,” by

  [21] See “Etymology of Word” in preceding chapter.

  [22] “New English Dictionary,” Murray.

“When succulent organs of the higher plants, no longer in the bud
condition, are injured, the wound generally becomes closed up by cork
tissue, i.e., new cells arise near the wounded surface by repeated
division of those which are yet sound, and these forming a firm skin
separate the inner tissue from the outer injured layers of cells. The
walls of this tissue offer the strongest resistance to the most various
agencies, similar to the cuticular layers of the epidermis in their
physical behavior, flexible and elastic, permeable only with difficulty
by air and water, they for the most part soon lose their contents and
become filled with air. They are arranged in rows lying at right angles
to the surface or parallelopipedal form, and form a close tissue without
intercellular spaces. These are the general distinguishing features of
cork tissue. It is formed not only on wounded surfaces, but arises in
much greater mass where succulent organs require an effectual protection
(e.g., potato tubers) or where the epidermis is unable to keep up with
the increase of circumference where growth in thickness continues for a
long period. In these cases the cork tissue is formed even before the
destruction of the epidermis, and when this splits under the action of
the weather and falls off, the new envelope formed by the cork is
already present. The cork tissue is the result of repeated bipartitions
of the cells by partition walls, rarely in the epidermis cells
themselves, more often in the subjacent tissue. The partition walls lie
parallel to the surface of the organ, divisions also taking place in a
vertical direction, by which the number of the rows of cells is
increased. From the two newly formed thin-walled cells of each radial
row one remains thin walled and rich in protoplasm, and in a condition
capable of division; the other becomes transformed into a permanent cork
cell. Thus arises, usually parallel to the surface of the organ, a layer
of cells capable of division, which continues to form new cork cells,
the cork cambium or layer of phellogen. In general this is the innermost
layer of the whole cork tissue, so that the production of cork advances
outwardly and new layers of cork are constantly formed out of the
phellogen on the inner surface of those already in existence. When in
this manner a continuous layer of cork arises, steadily increasing from
the inside, it is termed “periderm.” As the epidermis is at first
replaced by the periderm, so in turn is this replaced by cork (the dead
tissue). The development and configuration of the cork cells may change
periodically during the formation of periderm. Alternate layers of
narrow, thick-walled and broad, thin-walled cork cells are formed; the
periderm then appearing stratified, like wood, showing annual rings as
in the periderm of the Quercus Suber, Betula Alba, etc.”

Mr. Sacks, as a botanist, has clearly set forth the explanation of the
formation of the periderm of the Quercus Suber in the foregoing, and
although the story of the life producing this formation would be an
acceptable sequel to this explanation, it would in no wise assist in the
ultimate findings, and therefore it is dispensed with. Mr. William
Anderson, in a paper read at the Royal Institution of Great Britain in
1886, has the following to say on cork formation, which is very
interesting: “In considering the properties of most substances, our
search for the cause of their properties is baffled by our imperfect
powers and the feeble instruments we possess for investigating molecular
structure. With cork, happily, this is not the case; an examination of
its structure is easy and perfectly explains the cause of its peculiar
and valuable properties. All plants are built up of minute cells of
various forms and dimensions. Their walls or sides are composed chiefly
of a substance called cellulose, frequently associated with lignine, or
woody matter, and with cork, which last is a nitrogenous substance found
in many portions of plants, but is especially developed in the outer
cork of exogenous trees, that is, belonging to an order, the stems of
which grow by the addition of layers of fresh cellulose tissue outside
the woody part and inside the bark. Between the bark and the wood is
interposed a thin fibrous layer, which in some trees is very much
developed. The corky part of the bark which is outside is composed of
closed cells, exclusively, so built together that no connection of a
tubular nature runs up and down the tree, although horizontal passages
radiating toward the woody parts of the tree are numerous. In the woody
part of the tree, on the contrary, and in the inner bark, vertical
passages or tubes exist, while a connection is kept up with the pith of
the tree by means of medullary rays. In one species of tree, known as
the cork-oak, this is strongly developed.” It appears that Mr. Anderson
enlivened his lecture by microscopic projections, for he goes on to say:
“First I project on the screen a microscopic section of the wood of the
cork tree. It is taken in a horizontal plane, and I ask you to notice
the diversity of the structure and especially the presence of large
tubes or pipes. I next exhibit a section taken in the same plane of the
corky portion of the bark. You see the whole substance is made up of
minute many-sided cells about 1/750 of an inch in diameter and about
twice as long, the long way being disposed radically to the trunk. The
walls of the cells are extremely thin and yet they are wonderfully
impervious to liquids. Looked at by reflected light, bands of silvery
light alternate with bands of comparative darkness, showing that the
cells are built on end to end in regular order. The vertical section
next exhibited shows a cross section of the cells like a minute
honeycomb. In some specimens large crystals are found. These could not
be distinguished from the detached elementary spindle-shaped cells, of
which woody fiber is made up, were it not for the powerful means of
analysis we have in polarized light. I need hardly explain that light
passed through a Nicol’s prism becomes polarized, that is to say, the
vibrations of the luminiferous ether are all reduced to vibrations in
one plane and consequently if a second prism be interposed and placed at
right angles to the first, the light will be unable to get through; but
if we introduce between the crossed Nicol a substance capable of turning
the plane of vibration again, then a certain light will pass. I have now
projected on the screen the feeble light emerging from the crossed
Nicol. I introduce the microscopic preparation of cork cells between
them, and you see the crystals glowing with many colored lights on a
dark ground. Minute though these cells are, they are very numerous and
hard, and it is partly to them that is due the extraordinary rapidity
with which cork blunts the cutting instruments used in shaping it.” In
his research or experimentations Mr. Anderson was most deeply impressed
with the elasticity of cork, and has the following to say upon his
findings: “It would seem difficult to discover any new properties in a
substance so familiar as cork, and yet it possesses qualities which
distinguish it from all other solid or liquid bodies, namely, its power
of altering its volume in a very marked degree in consequence of change
of pressure. All liquids and solids are capable of cubical compression
or extension, but to a very small extent; thus water is reduced in
volume by only .00005 part by the pressure of one atmosphere. Liquid
carbonic acid yields to pressure much more than any other fluid, but
still the rate is very small. Solid substances, with the exception of
cork, offer equally obstinate resistance to change of bulk; even India
rubber, which most people would suppose capable of very considerable
change of volume, we find it really very rigid. Metals, when subjected
to pressure which exceed their elastic limits so that they are
permanently deformed, as in forging or wire drawing, remain practically
unchanged in volume per unit of weight. Not so with cork, its elasticity
has not only a very considerable range, but it is very persistent. Thus
in the better kind of corks used in bottling champagne and other
effervescing wines, you are familiar with the extent to which the corks
expand the instant they escape from the bottles. I have measured this
expansion and find it to amount to an increase of volume of seventy-five
per cent; even after the corks have been kept in a state of compression
in the bottles for ten years.[23] When cork is subjected to pressure,
either in one direction or from every direction, a certain amount of
permanent deformation or permanent set takes place. This property is
common to all solid elastic substances when strained beyond their
elastic limits, but with cork the limits are comparatively low.” To take
advantage of the peculiar properties of cork in mechanical applications
it is necessary to determine accurately the law of its resistance to
compression, and for this purpose Mr. Anderson instituted a series of
experiments of this kind. Into a strong iron vessel of five and one
half gallons’ capacity he introduced a quantity of cork and filled the
interstices with water, carefully getting out all the air. He then
proceeded to pump in water until definite pressures up to one thousand
pounds per square inch had been reached, and at every one hundred pounds
the weight of the water pumped in was determined. In this way, after
many repetitions, he obtained the decrease of volume due to any given
increase of pressure. The observations have been plotted into the form
of a curve which is discernible on the accompanying diagram.

  [23] Showing a permanent set of 12.5 per cent.

[Illustration: VOLUME OF CORK]

The base line represents a cylinder containing one cubic foot of cork
divided by the vertical lines into ten parts; the black horizontal
lines, according to the scale on the left-hand side, represent the
pressures in pounds per square inch which were necessary to compress the
cork to the corresponding volume. Thus to reduce the volume to one half,
required a pressure of two hundred and fifty pounds per square inch. At
sixteen hundred pounds per square inch the volume was reduced to
forty-four per cent, the yielding then becoming very little, showing
that the solid parts of the cells had come together and formed a solid,
compact mass, thus corroborating Mr. Ogston’s determination that the
gaseous part of cork constitutes about fifty-three per cent of its bulk.

In further study it has been found that no matter what compression is
used, providing there is no disintegration, the corkwood will retain
just that slight spongy character that so marks its growth.

In analyzing this solid matter, Ure found by treating it with nitric
acid the yielding was:

  White fibrous matter (cellulose).  0.18 parts
  Resin ........................... 14.72   “
  Oxalic acid ..................... 16.00   “
  Suberic acid .................... 14.4    “
                                    45.30 parts

Chevruel in an analysis of corkwood states that he found the following
constitutents, but he does not give percentages:

  Cerin, a soft fragrant resin.
  Yellow and red coloring matter.
  Quercitannic acid.
  Gallic acid.
  A brown nitrogenous substance.
  Salts of vegetable acids.
  Suberic acid.
  Suberin (cellulose).

I am inclined to think that Chevruel selected a poor grade of cork, full
of stone cells and Jasperado, as his findings include much that would
indicate that was the case.

In further defining the various substances which go to make up the body
of corkwood the one that is most impressive is that substance that is
peculiar to cork itself, the others being readily known, but suberic
acid is the one of interest, and this is described by Fownes as a
product of the oxidation of cork by nitric acid; is a white crystalline
powder, sparingly soluble in cold water, fusible and volatile by heat,
the chemical formula given being (C_{4}H_{14}O_{4}). Suberic acid is
also described as a dibasic acid which forms small granular crystals
very soluble in boiling water, alcohol and ether. It fuses at 300
degrees Fahrenheit and sublimes in acidular crystals. It is also
produced when nitric acid acts on stearic, margaric or oleic acid. The
chemical analysis is given as (C_{8}H_{14}O_{4}) and I am inclined to
believe it is the truer one, as it is much later than Fownes’.

This suberic acid has been further broken up to ascertain its
fundamental characteristics and it was found to partake of the two
compounds suberone and suberate.

Suberone (C_{14}H_{24}O_{2}) being regarded as the ketone of suberic
acid, an aromatic liquid compound obtained when suberic acid is
distilled with an excess of lime.[24] Also described as a colorless oil
with an odor of peppermint and a boiling point of 179 to 181 degrees
Centigrade, chemical formula, Suberone—Cycloheptanone—

     CH_{2} . CH_{2} . CH_{2}
     CH_{2} . CH_{2} . CH_{2}

  [24] “Standard Dictionary.”

Suberate (C_{8}H_{12}M_{2}O_{4}) is known as the salt of suberic acid
having a metal cast,[25] and Suberin or cellulose[26]—is that portion
remaining after nitration and is chemically expressed by the formula
(C_{6}H_{10}O_{5}). Dr. Robert K. Duncan, Prof. of Industrial Chemistry
in the University of Kansas, informs us that this material is the
commonest of common things[27] and when dry, forms one third of all the
vegetable matter in the world. This mysterious substance is the
structural basis of the wood, but with all its prominence and use, we
know nothing more about it than that which is expressed in the formula.

  [25] “Watt’s Dictionary” (“M” signifying metal).

  [26] “Century Dictionary.”

  [27] _Review of Reviews_, September, 1906.

The presence of this cellulose is only a natural fact, as the greater
part of plant life is cellulose; nor is the list of elements that go to
make up the solid matter so strange and unaccountable, but the quality
that makes it a wonderful growth and so popular above its fellows is its
lightness—this is its commendable feature and it is light indeed.

Ure puts the specific gravity at .24 and this is concurred in by


Two tests were made on this material to ascertain the presence of an
essential oil. The first showed the presence of an oily film,
resplendent in colorings, opalescent, variegated and beautiful, but
odorless and of such small quantity that it may safely be said “No Oil.”

The second proved the same as the first, and although the strong odor of
cork or suberic acid was present, no oil appeared.

The results of these tests indicate that there is no essential oil in
corkwood obtainable by steam distillation.



A copper still, supported on two trunnions, fitted with a dome and
goose-neck, which terminated in a tin coil (water cooled), and with a
perforated bottom through which the steam passed, was used.

This measured two inches in diameter and two inches high, from the
perforated plate to the top of the pot, the dome being about one foot

Into this still was placed 41 pounds of corkwood, as it comes from the
cutters and punchers (scrap pieces), no preliminary washing or preparing
being done; this 41 pounds filled the pot or the still.

All things made tight, using an asbestos packing, the steam was turned
on at 70 pounds and run for one hour.



Same still used as in Test No. 1, thirty pounds of a clean, good grade
Granulated Cork, of a fineness to pass a 1/16″ mesh, was put into the
still—this half filling same.

Steam turned on at 70 pounds and run for one hour.

Tests made at A. J. Crombie & Co., Brooklyn, N. Y.

       *       *       *       *       *

Anderson, Ure, Chevruel, Fownes, Watts, Brisbane, men of science; to
these we are indebted for the little that is known of corkwood, and
although perhaps much more could be said by elaboration, it will suffice
to record the facts in this monograph for the purpose involved.

But to the data assembled may be added much in commentation, for the
material becomes more interesting the more it is studied, and most
naturally excites comparison with other materials and substitutes, as
well as calling forth a discussion as to the dangers involved by its
presence in the places where, by skill of hand and machinery, it is
transformed into the many commercial forms, noted in this article. We
comment upon its growth, which is truly wonderful and all-absorbing in
its many interesting phases; it takes us to the romance of the East and
the enchantment of the Moorish occupation; through which these forests
of cork-producing trees passed and yet remain to furnish the present
generation. We comment upon its lightness and buoyancy, due to the
presence of air and excess of hydrogen, known to be lighter than air;
and the small percentage of other matter which, being of less
importance, make its other quality so renowned as to make it the most
wonderful growth of its kind. Its imperviousness to water and other
liquids have given us moments of reflection, upon this phenomenon, but
now known to be because of the cellulose composing the cell walls and
which, when the substance is under compression, practically is all that
remains, except for the small quantity of resin, etc., to resist the
passage of liquids or gases. But heretofore when these commentations
have reached the burning point, its physical nature was entirely
eliminated from the conjecturing and the important part neglected, that
as the cork contained fifty-three per cent of air, heat of 450 degrees
expands to the point of explosion, the contents of those cells nearest
the surface, which giving up their oxygen feed the flames and in their
passage help to disintegrate the cell walls and make them more easily
ignited. Thus causing a rapid burning, flash fire which, in its fury,
Pluto could not rival, only racing over the surface of the cork, burning
but slightly, yet helped by other conditions, resulting in a fire
destructive and fierce. This rapid burning leaves the outer surface of
the cork charred and flaky and causes a discoloration beneath it
attributed to the dissolving of the resins, etc. Of course where there
is a large quantity of corkwood the extent of the burning must
necessarily be greater and the depth of the char increased. But it
appears that the first flash burning produces a sort of protection coat
of carbon around the remaining unburned portions which a subsequent
flame penetrates with difficulty.[28]

  [28] In the making of insulation material, the carbonization of the
       cork is accomplished without destruction of fibre and stands a
       high flame test.

A simple experiment to show this depth of burning, and one that is easy
to do, is the flash and flame test which was found of interest.

Two pieces of cork were taken, having the following measurements—8/16″
× 7/16″ × 11/16″—and the first piece held so that the flame of a gas
jet would cause a flash over its surface; then the second piece is taken
and held within the flame for a minute.

It will be found that the corkwood has expanded and the dimensions
increased to the following:

        Flash                         Flame
  8/16″ × 13/16″ × 11/16″      10/16″ × 14/16″ × 11/16″

showing the effects of the heat upon the tissue and contents of the

Now in scraping these samples clean of all char the dimensions will
return to the following:

        Flash                         Flame
  6/16″ × 11/16″ × 11/16″        8/16″ × 10/16″ × 11/16″

clearly setting forth the fact that the char is comparatively light in
both cases, ranging from 1/8″ to 1/4″.

To this cause is ascribed the burnability of cork having by careful
observation and experiment, extending over a period of two years,
studied the results of numerous fires in premises where cork was being
worked and also conducted heat applications on various grades of
cork[29] resulting in the foregoing findings.[30] Thus it is found that
cork contains sufficient air to supply any fire in it and precludes the
necessity of free access to any outside supply which makes it a material
worthy to be watched. To its many qualities of great service to man,
giving him a material which from the ages past, till now, has proven of
such value, must be added this one, no less important than others, which
heretofore have been its commendable features.

  [29] Using ordinary glass (armoured) thermometer for ascertaining

  [30] One thousand degrees Fahrenheit, causing no greater combustion
       than the lower degree, other than the increased burning of
       remaining substance after the flash, due to the higher

Rather than attend the “cork” through the many passages of commerce and
manufacture, it is deemed propitious to deviate a little from a natural
course, i.e., from the growing to manufacture and rather advance to a
knowledge of the many uses to which this material is put and its
application to the innumerable arts, and then take up the manufacture.


Mr. H. G. Glasspoole,[31] writing regarding the uses of cork by the
ancients, states: “The cork-tree, and the application of its bark to
useful purposes, was well known to the Egyptians, Greeks and Romans. The
former used this material in the construction of the coffins for their
dead. Theophrastus, the Greek philosopher, who wrote on botany four
centuries B.C., mentions this tree among the oaks, under the name of
‘Phellus’ in Book Two of his ‘Historia Plantarum,’ and stated that it
was a native of the Pyrenees, having a thick fleshy bark which must be
stripped off every three years to prevent it from perishing. He adds
that it was so light as never to sink in water, and on that account
might be used for many purposes.” It is the opinion of the writer that
the attention of the ancients was undoubtedly called to this particular
bark by its buoyancy, and as their fisheries were extensive its
usefulness became readily apparent to float nets, etc., or to use
even in the construction of their boats, and its sponginess and
water-repellent properties not escaping their notice, it became a most
likely material for stoppers of casks or amphorae as noted by Horace in
Ode iii, 8: “Corticem adstrictum pice dimovebit amphorae.” Pliny, in his
“Natural History,” XVI, 18, describes the tree under the name of Suber
and relates everything said by Theophrastus of Phellus. From his account
we learn that the Roman fishermen used it as floats to their nets and
fishing tackle, and as buoys to their anchors. The use of these buoys in
saving life appears to have been well known to the ancients, for Lucian,
Epist. i, 17, mentions that when two men, one of whom had fallen into
the sea, and another who jumped after to afford him assistance, both
were saved by means of an anchor buoy. The use of this substance in
assisting swimmers was not unknown to the Romans, for Plutarch in his
Life of Camillus, who flourished in Rome 400 B.C., gives an account of
its use by a messenger, sent to the Capitol, then besieged by the Gauls:
“Pontius Cominius having dressed himself in mean attire under which he
concealed some pieces of cork. He could not pass the river by the
bridge, therefore took off his clothes, which he fastened upon his head,
and having laid himself upon the pieces of cork swam over and reached
the city.” The use of cork as stoppers was entirely unknown to the
Romans, but instances of its being employed may be seen in Cato’s “De Re
Rustica,” Cap. 120, but this did not happen frequently or more would be
said of it.

  [31] _Scientific American Supplement._

The convivial customs of those days had no connection with the bottle,
glass bottles being of a much later invention. Instead of having
champagne or hock to be liberated from the bottle by the corkscrew at
their feasts, the guests filled their drinking cups of gold, silver,
crystal or beechwood from a two-handled amphora, a kind of earthenware
pitcher, in which their choice wines used to be kept. The mouths of
these vessels were stopped with wood and covered with a mastic, composed
of pitch, chalk and oil to prevent air spoiling the wine or evaporation
taking place. Columella, who wrote one of the earliest works on
agriculture, gives directions for preparing this cement.

The employment of cork for stoppers of bottles appears to have come into
use about the seventeenth century, when glass bottles, of which no
mention is made before the fifteenth century, began to be generally
introduced. Before that period apothecaries used stoppers of wax, which
were not only much more expensive but far more troublesome. In 1553,
when C. Stephanus wrote his “Praedium Rusticum,” cork stoppers appear to
have been very little known in France, for he states that this material
was used principally for soles in that country. It is not known when
cork and corks began to be generally used, but in that very amusing and
instructive diary of Mr. Samuel Pepys the following entry is found: “14
July 1666” After having written to the Duke of York for money for the
fleet, I went down Thames Street and there agreed for four or five tons
of cork to be sent to the fleet, being a new device to make barricados
with instead of junts (old cable),” but he does not inform us how the
material answered.[32]

  [32] I have subsequently learned that this proved a failure.

In Evelyn’s time (1664) cork was much used by old persons for
linings to the soles of their shoes, whence the German name for it,
“Pantoffelholtz” or slipper wood. The Venetian dames, Evelyn says, used
it for their choppings or high-heeled shoes to make them appear taller
than nature intended they should be. The poor of Spain lay planks of
cork by their bedside to tread on instead of carpets. Sometimes they
line the inside of their houses, built with stone, with this bark, which
renders them very warm and corrects the moisture of the air. Loudon
relates that in the celebrated convent at Cintra, Portugal, several
articles of furniture are made of this tree. Virgin cork, or the first
bark of the tree, is now very much used for window flower boxes,
grottoes, etc., while the subsequent grades are used for small
architectural and geognostic models. Cork was formerly employed in
medicine even as far back as the time of Pliny, as he tells us that the
bark of the cork tree, pulverized and taken in warm water, arrests
hemorrhage at the mouth and nostrils, and the ashes of it taken in warm
wine are highly extolled as a cure for spitting blood (see Pliny, “Nat.
Hist.” b. 124). In modern time powdered cork has been applied as a
styptic and hung about the necks of nurses. It was thought to possess
the power of stopping the secretion of milk. Burnt cork mixed with sugar
of lead has been used as an application to piles. See Pereira’s “Materia

Ground cork and India rubber formed the basis of Kamptulicon, the soft
unresounding material which covered the floor of the reading rooms of
the British Museum.” In further describing the many uses to which cork
is applied, reference is made to the résumé of Mr. Good in “La Nature,”
which is incorporated with a few slight changes.

“The various applications of cork that we are now going to pass in
review are worthy of description, as each of such applications has its
_raison d’être_ in one or more of the physical or chemical properties of
cork bark. The manufacture of stoppers utilizes, in the first place, the
impermeability of the bark, and, in the second, the latter’s elasticity
and imputrescibility, the remarkable lightness playing no rôle therein.

Before entering upon a study of the industrial applications of cork, in
grouping them according to the various qualities of this product, we
must return to the “male” cork, derived from the first barking of the
tree. It has been said, because of its slight elasticity and numerous
fissures, this product has but little commercial value, and shall have
mentioned its principal application when we have stated that it is used
in the decoration of parks and gardens. An endeavor has been made, but
without success, to manufacture from it, mills for decorticating rice.

Certain parts of it can be converted into small stoppers. In the country
where it is produced, it is used for making water conduits, beehives and
shelves on which to preserve objects from dampness. Mixed with a mortar
of clay, the Kabyles use it for the walls of their dwellings, and also,
in lieu of tiles, as a roofing material for their primitive habitations.
It is used also by fishermen as floats for their nets.

These various applications were known to the Greeks and Romans, as shown
by the works of Theophrastus and Pliny. The latter says of the cork-oak:
“Nothing is utilized but its bark, which is very thick, and which is
renewed in measure as it is removed. This bark is often used for the
buoys of anchors and ships and of fishermen’s nets, for the bungs of
casks, and for women’s winter foot gear. The Greeks called the cork-oak
the ‘bark tree’.... Cork bark is used as a covering for roofs.” (“Hist.
Nat.,” xvi, 18.) As for the chips, they can be used as an isolating
material to prevent freezing. Reduced to fragments, they furnish an
excellent material for covering circus rings.

Let us return to “female” cork, which is much better adapted for being
worked, and the grain of which is much more homogeneous. In this form
cork bark constitutes a very bad conductor of heat and sound, and
renders valuable services in the industries as a material for
preventing the cooling of steam pipes and generators, and preventing
the melting of ice in ice houses, or the heating of apparatus for
producing cold.

It is the basis of a certain number of cements, and coatings for
preventing the escape of heat, which are applied to pipes, steam domes,
hot water reservoirs, etc., and upon the composition of which we shall
not dwell here. As for jacketing with cork alone; the first method
consists in placing narrow strips of cork, whose edges touch each other,
along steam pipes and cylinders, and fastening them by means of wire. A
pipe thus jacketed is tangent internally to all these strips, and a
section of the whole shows a circle inscribed in a polygon. In the
second system thin strips of cork, fastened to canvas with India rubber
cement, are wound around the pipe spirally. Finally, a third method of
jacketing consists in the use of two half cylinders that exactly fit the
exterior of the steam pipe. These cylinders, which can be made of any
desired length, are made of powdered cork and starch, and are covered
with a spirally wound strip of calico, which may be coated with tar or
any suitable kind of paint. Each of these systems permits of obtaining a
great saving in fuel.

As cork is likewise a very bad conductor of sound, it is successfully
used on the doors of consulting rooms, and for making floors for
hospitals, etc. Finally, in the manufacture of certain stringed
instruments, it is used to prevent a loss of sound.

The slight density of cork, as compared with water, and its
impermeability to liquids, make it an excellent float, capable not only
of remaining on the surface, but also of supporting quite heavy bodies
thereon. We shall be content to mention the annular cork float used in
night lamps, the square block in which bath thermometers are fixed, and
the fisherman’s dobber.

It is cork, too, that is used by preference in the manufacture of
swimming and life-saving apparatus, to which inventors have devoted much
thought. Very many vessels are provided with cork mattresses, which, in
cases of shipwreck, render the greatest services. For example, the ship
_Constant_, which sailed from Anvers for Brazil in 1845, was wrecked on
the night of October 12th, at twelve miles from St. Thanes, but, thanks
to the cork life preservers and mattresses that she had on board, not
one of the crew was lost. As for life-saving buoys, properly so called,
they consist of several cork planks which are given an annular form, and
are provided with free ropes that are knotted here and there so that
they may be easily grasped. From the stern of every vessel a buoy of
this kind is suspended by a rope that may be at once cut when the cry of
“A man overboard!” is heard. These buoys are usually covered with canvas
coated with a paint that serves to preserve it. It is also possible to
save a person who has fallen into the water at a certain distance from a
wharf by means of floats. This device consists of a piece of rattan
provided with points around which molten lead has been poured, and the
whole is then surrounded with cork in chips, and covered externally with
canvas and a network to protect the affair against wear.

Fenders are canvas bags that are filled with cork and are placed along
the sides of ships or along docks in order to deaden the shock in case
of a collision. Such are the principal uses rendered to navigation by

It has already been seen, by the extract from Pliny, that Roman ladies
preserved their feet from cold by means of cork soles. Such a use of
cork is still in vogue. In addition to these soles, which are flat,
there are others that have nothing to do with hygiene, and are merely
connected with fashion. Such are the Louis Quatorze talonettes, designed
to increase the stature without exaggerating the heel of the shoe.
Female dancers wear linings of this kind in their shoes, which, as well
known, have flat soles. A thin sheet of cork enclosed in the sole of the
shoe would, we think, prove very useful to troops on a march during bad

Cork is not only useful as an application to foot gear, but also renders
great service in head gear, and, in the form of helmets, has preserved a
large number of soldiers from death by sunstroke in tropical countries.
We find it again, in the form of very thin sheets, in the interior of
beaver hats, where it is used as a protection against heat. It is also
used in these same hats as a sweat band, in lieu of leather. In ladies’
toilets, the cork serves to make the carcasses of the birds that
decorate their head gear. Manufacturers of dress trimmings use cork
molds, which they cover with silk or cotton, for ornamenting cloaks,
etc. The lightness of cork can alone explain the great size of these
balls, olives, etc., some of which are larger than a hen’s egg.

A few years ago, a Paris house sold cork cravats, and we have recently
seen, exposed in a show case, some children’s costumes, in which the
sailor’s collar was of thin sheet cork decorated with colored designs.
Although cork gowns have not yet appeared, we have waterproofs composed
of thin sheet cork cemented between two pieces of silk. These cloaks
have the advantage over those made of rubber of not allowing air to pass
through them.

There is also a curious application of cork in the manufacture of a
fabric that renders those who are clothed with it insubmergible.

We can mention but few of the many applications of cork, new ones of
which are being discovered every day, so shall confine ourselves to
recalling the services rendered by this valuable product in surgical
prosthesis and for the use of naturalists, etc. In domestic life, it is
used for bath steps, and for making rolling pins for crushing almonds
without absorbing the oils as wood would do. Thin sheets of it are used
for making fancy labels for wines. The ease with which it may be cut,
turned and worked causes it to be employed in the manufacture of small
objects, such as rural landscapes and the reproductions of monuments,
some of which are genuine works of art. We may likewise mention, among
objects made of cork, cases of various forms for sending bottles by
mail, spools for allowing of the cheap carriage of silk, the
old-fashioned inkstand, the thick penholder for preventing writer’s
cramp, the cigar holder and many fancy objects that would take too long
to enumerate. There is perhaps no calling that does not have to make
more or less use of cork. Polishers of gold have used it from time
immemorial, in the form of narrow strips, for rubbing their work with
rouge. The wheels with which crystals are polished are faced with it,
and watchmaker’s lens mounted in cork, the lightness of which prevents
the muscles of the face from tiring.

In the industries, driving pulleys are now beginning to be provided with
cork in order to secure an adhesion of the belting. In carpenter shops
these bands of cork are now advantageously replacing rubber ones for
covering the pulleys over which the band saw runs. The stoppers of
nursing bottles are now being replaced by hygienic ones of cork, which,
being very cheap, can be changed as soon as the presence of ferments is
suspected. Cork is likewise employed in the manufacture of children’s
toys; it serves, for example, for fixing the wig on dolls’ heads. Is it
necessary to recall the cork of pop-guns and pistols, and the cork
battledores and shuttlecocks used for playing with indoors? These few
data will serve to show that but few products are capable of so many
diverse applications as cork is; and the question may be asked whether
it would be possible to substitute anything else for it, in case the
supply should become exhausted.

The manufacture of stoppers and of the various objects that we have just
enumerated furnishes a considerable quantity of chips, which along with
the waste derived from the collecting of the material, and with old,
second-hand corks, constitutes the crude material destined to supply
certain important industries, which, for the sake of completeness, must
be mentioned.

We have first the cork powder industry, which manufactures powders of
various degrees of fineness. The coarsest powder is used for packing
fragile objects, on account of its elasticity, coupled with its
lightness, which permits of a great saving in freight charges.

The finest powder forms, “liegine” or “suberine,” whose balsamic
properties are well known to hygienists, and which may be used as a
substitute for lycopodium, starch and fecula as an application to the
skin of babes. Under the name of “zifa powder,” an insect powder has
been made composed of cork and phenol. Fire lighters have likewise been
made from cork powder; but this and the last named application have not
amounted to much.

We cannot enter into much detail in regard to the manufacture of
linoleum, notwithstanding the interest that it presents. The manufacture
began in Scotland, and is tending to settle in our own country. Linoleum
is made by intimately mixing cork powder with oxidized linseed oil. The
paste thus prepared is spread over canvas if the intention is to
manufacture carpets, but over paper if it is desired to make hangings.
The color of linoleum, which is the same as that of cork, only a shade
darker, can be enlivened by colored designs. When applied to damp walls,
linoleum is capable of receiving oil paintings of a more stable nature
than those executed upon wood, which warps, or upon other building
materials, which crack, such as plaster, for example. It can also be
used for decorated ceilings for public halls, cafes, etc.; and when such
ceilings become black through smoke and dust, they can be washed.

As a carpet, linoleum renders flooring perfectly insonorous. It converts
damp and unhealthy apartments into healthy and warm places of
habitation. Used in kitchens and offices, it has the advantage of not
being spotted by fatty matters. It has been generally adopted in our
naval and merchant ships, where the use of it has given a great setback
to the oil cloth industry.

A new decorative product, “lino-burgau,” obtained by embossing linoleum,
possesses the iridescent reflections of nacre, due to the application of
colored varnish along with a bronzing of certain parts. Notwithstanding
its expensive nature, we believe that there is a great future in store
for it.

The manufacture of agglomerates of cork is becoming very widespread in
France. We have already mentioned the use of artificial cork for
jacketing steam pipes, and we have stated that this product is obtained
by mixing cork powder and starch under pressure. This dried paste can be
given the most diverse forms, and be made of any thickness. Another
substance, called brick paste, is obtained by mixing the coarsest cork
powder with milk of lime, and, after compression and drying,
constitutes, under the form of bricks and slabs, an excellent material
for the construction of party walls, for covering damp walls and sloping

In the cellars of breweries, these bricks diminish the melting of the
ice. In gunpowder works, they prevent the caking of the powder through
dampness, and, in case of an explosion, their friability and lightness
lessen the importance of the catastrophe. They are also used as a
foundation for flooring in order to destroy its disagreeable
sonorousness. In the spinning mills of Alsace and the west of France,
they have given excellent results, both as regards their resistance to
the passage of sound, heat and cold, and their cheapness.

Cork chips and waste, when distilled, furnish an illuminating gas that
burns with more brilliancy than that made from coal, and does not, like
the latter, give off sulphureous emanations that tarnish frames and
other gilded objects. The city of Nerac was lighted with cork gas for a
certain length of time, but the use of it had to be given up on account
of the difficulty of storing the chips, which, with but little weight,
took up an enormous space. This gas, in view of its slight density and
its purity, would prove an excellent one for the inflation of balloons.

Finally, cork parings and waste, properly carbonized, produce Spanish or
cork black, one of the most beautiful and durable blacks known in

The recent uses for corkwood are, as a float in the carburetter of an
automobile, the cork insert in the periphery of a pulley,[33] cork paper
for cigarette tips, a wadding for shot-gun cartridges, cork-coated
fabric for balloons, as a filling for automobile tires, as a disk in the
non-refillable bottle, for the making of casks and barrels in which to
store wine, and the ground cork wood for shipping fruit, etc. in, to
prevent spoiling.

  [33] See Lawrence Whitcomb’s article in _Industrial Engineering_,
       September, 1910.


Of course, no matter what the substance, a substitute is always sought
for, and this has been the case with cork, but with very unfruitful
results. “A primitive material used for bottle stoppers consisted of the
roots of liquorice; the spongy substance of another tree called
‘Spondies Lutea,’ which abounds throughout the marshy regions of South
America and there called ‘Monbia,’ was also used in the same way, as
also a product called ‘Myssa,’ which contains some of the elements of
cork.[34] Another substitute is mentioned in Henley’s “Twentieth Century
Receipts” as follows: Wood pulp three parts; cornstarch pith one part;
gelatin one part; glycerine one part; water four parts; 20 per cent
solution formic aldehyde; and still another in the “Handyman’s ‘Inquire
Within,’” by Haslock, called “Phellosene,” a French invention consisting
of powdered cork mixed with a solution of nitro-cellulose in acetone:
compressed and dried. The wood of Anona palustris growing in the West
Indies, and called the alligator’s apple, is used by the negroes to stop
their jugs and calabashes also, and a Mr. Brockedon invented a
substitute as noted in “Knight’s Cyclopedia,” the core of which was
cotton twisted into strands, wound with flax and the whole covered with
India rubber. Cork’s competitor in buoyancy, “balsa wood,” is in no wise
constituted to take its place, although 20 per cent lighter; as it is a
fibrous growth and hygroscopic, requiring a coat of water-proofing
solution before it can be used even for life-preservers; rubber, its
close second, in the manufacture of stoppers is not to be compared with
it, and although there have been many patent devices for sealing
bottles, such as the porcelain stopper, crimped metal stoppers, etc.,
the cork stopper still reigns as the best of them all.

  [34] _Chambers Journal._


In describing the manner and process of converting the corkwood into the
various commercial forms, no attempt will be made to give a scientific
exposition of all the details, as being inconsistent with the character
of this monograph, nor will any other processes be described than the
ones in which the material being worked, is cork. This may exclude much
of interest to the reader, but the intent of this little work is purely
a corkwood exposition, and the desire to keep it so must prevail.

                     / | \
                    /  |  \
                   /   |   \
                  /    |    \
                 /     |     \
                /      |      \
               /       |       \
              /        |  VIRGIN-CORK WOOD
             /         |       /
            /          |      /
           /           |     /
          /{OF         |    /
          |{SIZE       |  /
          |            | /
          |            |/
          |           /|
          |          / |
          |         /  |
          |        / CORK DISKS
        WASTE     /    |
          |      /  WASTE
          |     /    /
          |    /    /|\
          |   /    / | \
          |  /    /  |  \
          | /    /   |   \
          |/    /    \    \
       CORK BOARD     \    \
                       \    \CORK DISKS
                      /  \
                     /    \
                    /\     \GRANULATED PACKING
                   /  \         MATERIAL
                  /    \
                 /      \
               CORK      \
              FLOUR       \
                |          \
                |           \SPANISH BLACK

In taking up the processes of manipulation we naturally start from the
beginning, but the beginning in this case has a peculiar significance as
relating to the whole, for it is apparent to utilize corkwood to the
fullest extent its qualities must be studied and the best, used first,
so that the beginning of the corkwood industry is peculiar in this fact,
that it takes the best part and leaves but scrap, which must be studied
carefully to realize the value lost in the first process; therefore, in
the manufacture of one article of corkwood it is necessary to make
provision for the scrap created, and this is a characteristic of all
such establishments.


The baled cork, as received, is our first consideration, for its bulk,
being out of all proportion to its value, attracts the attention at

As in all business where the raw stock is conveyed from a distance and
there is a possibility of delay in shipments, a large stock must
necessarily be kept on hand, and this feature is very pronounced in and
about a “cork factory.” Great piles appear in the open or within large
sheds, covering much space, and sometimes in the factory itself.

This stock is carefully watched and care taken to keep it large enough
to supply all needs for a long time as a shortage in raw material would
not only mean no work, but the loss of business, due to the inability to
supply first-grade material, for this is the prime factor, the various
other grades being compelled to await a favorable market. Appended is a
diagram that will give some idea of the utilization of corkwood.

The corkwood bale as received, measures as a general rule 2′ × 2′7″ × 4′
and is securely strapped with iron bands about one inch in width and a
thickness of 1/16″ to 1/32″, and the weight depending upon the quality
of corkwood ranging from 150 pounds to 200 pounds per bale.


The first operation, that is, the first thing done with the corkwood, is
the sorting. This is becoming more important as the uses of cork
increase, as various grades can be used for so many particular things
now, without the necessity of being called a by-product; but the
principal divisions are: superfine, fine, common and coarse.

These of course are now extended to many classes, and is resulting in
careful scrutiny of the shipments and stock, the sorter becoming an
expert, and an increasing factor in the business. His knowledge not only
including the grades of corkwood, but the uses to which the various
grades may be put so that waste is avoided and the full value gotten out
of all.


After the sorting, the slabs are placed in steam boxes and subjected to
a steam bath, which it is claimed softens the material and also prepares
it for the scraper, who cleans and removes the dirt and callous or
“raspa” accumulated in its mountain home. This scraping is done either
by hand or machine, the handwork being done with a short handle, curved
bladed knife called a “doladera,” raspador or raspeta: a workman being
able to scrape from two to three metric quintals of cork in a day, or
ten hours. The scraper machine being a vertical steel shaft carrying
several knives placed at a very slight helix and making about 1400
revolutions per minute and will scrape from ten to twelve metric
quintals[35] per day or ten hours. Cutting the slabs into strips or
fillets (tiras ó’rebanadas) is the next step. These strips, the width of
which is equal to the length of the cork to be cut, as the cutting is
done across and not with the grain, were formerly cut by hand with a
knife having a flat surface and curved edge called “cuchilla de
rebanar,” but now replaced by the circular knife, which operates the
same as a rip-saw. From here the strips go to the stopper-makers’
punches or blocking machines. This machine has a rotating tubular die
with sharpened edges of the diameter of the cork to be cut, made to
revolve about two thousand revolutions per minute, the operator having a
foot lever attachment which permits him to thrust the die through the
strips of cork as he holds it against a resisting piece parallel with
the operating plane of the die. Thus, he can punch out many thousands of
corks a day, the noise of the punches being a very characteristic sound
in all such establishments. The operator, of course, must use care to
avoid defective spots in the bark, and also to cut the corks out as
closely together as possible so as to reduce waste to a minimum. For it
is here that the cork manufacturer seems to lay his particular lament.
If he could but make his corks the sizes most in demand, ship them and
thereby do a business that would clearly figure up the year’s work, and
perhaps keep a surplus on hand for unexpected orders. But this he cannot
do, for almost every cork he cuts there is enough waste material to make
three or four smaller sizes, and this he fain would discard if it were
not for the possible profit there is in it; and consequently in almost
every cork factory will be found a large surplus stock of all sizes, and
the owner anxiously hoping that some one will take them off his hands.

  [35] The metric quintal is used officially in Spain, which is equal
       to 220.36 pounds, the Catalon quintal equaling 91.71 pounds.

The stoppers which come from these machines are round with parallel
sides. If tapered corks are desired, larger at the upper end than at the
lower, the cylindrical or straight pieces must be passed through another
machine which handles them deftly, holding them against the edge of
another circular knife; seemingly motionless, the only outward
indication of the speed with which the keen blade is revolving being a
delicate shaving which curls upward for an instant, and then is drawn
away by air suction to the waste bin, where this material is all
collected and used in various, useful ways as will be shown later. In
cutting the corks, although care is exercised, many will be imperfect
and defective, and in order to utilize them they are cut into smaller
sizes by men who sit at low tables and deftly handle the sharp-edged
knife, which with one stroke reduces the cork to the size that it can
fill, using a scale which is apparently standard with all cork dealers.

The general standard of corks or stoppers, known as the United States
standard, is as follows:


_United States Standard, showing Diameter at Large End_

  No. 0       3/8 inch      No. 1       7/8  inch.
   “  2       1/2   “        “  3       9/16   “
   “  4       5/8   “        “  5      11/16   “
   “  6       3/4   “        “  7      13/16   “
   “  8       7/8   “        “  9      15/16   “
   “ 10     1       “        “ 11     1-1/16   “
   “ 12     1-1/8   “        “ 13     1-3/16   “
   “ 14     1-1/4   “        “ 15     1-5/16   “
   “ 16     1-3/8   “        “ 17     1-7/16   “
   “ 18     1-1/2   “        “ 19     1-9/16   “
   “ 20     1-5/8   “        “ 24     1-7/8    “
   “ 22     1-3/4   “        “ 26     2        “

Length is generally designated as short, regular, extra long, and the
shape as tapered, or straight.

This classification of necessity applies to the trade and gives a size
for almost any character of work there is, though another general
classification that is used principally abroad, is as follows:—

  Thick corks having more than 31 millimeters[36] in diameter.
  Ordinary or commercial, from 25 to 31 millimeters.
  Bastard corks, from 23 to 25 millimeters.
  Thin corks, having less than 23 millimeters.

  [36] Millimeter = .0394 inch.

These classes of sizes are of course divided again and again by the
manufacturers. To this size classification must be added a quality
distinction, and this generally takes the same as before described, in
sorting the cork-board, grading down from the best which is tawny or
pink in color, with a fine texture, free from cracks, stone cells, or
other blemishes.

As has been stated, the punch is now employed in most corkwood
establishments, but there are still a few who do the work by hand and
maintain that the best results are obtained in this manner.

Hand-cut corks or stoppers are used mostly for the high-class wine trade
and are a little more expensive than machine cut. There is also a hand
machine for shaping corks, which consists of a knife, the blade of which
is placed horizontally, joined generally to a piece of wood, to which a
back and forward movement is given similar to that of a carpenter’s
plane. In moving, the knife turns the square cork, or whatever shape it
may be, by a series of belt attachments, and takes off a strip of cork
(palilla) more or less thick, according to the distance from the axis of
the cork and the edge of the blade; the principle being the same in the
power machine, if these are parallel the resulting cork will be
cylindrical, and if not, it becomes conical.

The standard size stopper is the prime use to which corkwood has been
put, and in the making of it the best material is used; this material
coming in varying thicknesses, it sometimes is difficult to secure
enough for making “champagnes,” so some manufacturers produce a stopper
that answers the requirements by fastening two pieces of thin superfine
corkwood together with a rubber cement made by dissolving pure Para
rubber in disulphide of carbon, which makes a very good binder and not
lessening the quality service to any appreciable degree.

After the corks are cut, the ends are not always as even and as smooth
as desired, so they are taken to a sandpaper wheel which revolves very
rapidly in an upright position, and against this the corks are held for
a few seconds until the surface becomes smooth and straight, the dust
created being collected and used in various ways. (See “Waste


(See “Waste Utilization”)

Since the Crown Seal stopper, for beer bottles particularly, has come
into vogue, there has been a great demand for cork disks which form the
medium for air tightness and this has given the cork-worker an
opportunity to utilize a grade of corkwood that usually had but little
commercial value, that is, a thin bark.

It may be well to state here for the uninitiated that the Crown Seal is
made up of a tin cap, corrugated on the lapped edge, for gripping the
top of the bottle, a corkwood disk and a water-proof paper between the
disk and cap, a very ingenious device.

As you have already read in a previous chapter that corks are cut
vertical parallel, or, to state more clearly, the axis of the stopper
must be parallel with the axis of the tree that furnished the bark; and
the desired direction is easily recognizable by the colored striae due
to the annual layers of suberous substance that are observed in the
direction of its axis, this rule being followed because cork is found to
be more impervious to liquids if cut in this manner. It will be readily
seen that if disks are cut horizontally parallel, that is, the annual
layers running at right angles to the axis of the disk, this grade of
cork can be utilized to great advantage. The mode of cutting is by a
horizontal revolving blade, which slices the cork to the desired
thickness, usually a quarter of an inch, and then it follows the usual
course of punching, etc. From these operations a great deal of waste
accumulates, and this would be a great loss if methods were not devised
for its utilization. Many firms work up this waste on the premises, but
most of it is shipped out and its conversion forms a separate part of
the corkwood industry, which will be described later. We might say now
that the cork is made, for it has been cut and shaped into the desired
commercial size; and all that remains is to sort them and ship them
away. But if commerce desires sizes and quality, it has also exacted
many other requirements of a cork before it is acceptable and we will
now take up the further manipulation of cork before it leaves the
factory. Naturally, this corkwood, coming such a distance and being
handled by so many in the general processes just described, gets more or
less dirty, and aside from that perhaps in the growing the tissue has
not remained as white as is desired, so before the cork can leave the
factory it has to be washed or cleaned. And in this washing I will not
say that there is not an attempt to improve the looks of the corks in
order to get a better price. Now this washing or bleaching is carried on
in the simplest manner and is just soaking the corks in water and a
chemical and then placing them in a centrifugal spinner, which is
nothing more than a perforated receptacle made to revolve within an iron
jacket, which is connected to a drain, naturally forcing the material
against the periphery and thereby causing the excess water and acid to
pass out through the perforations, this system becoming quite common in
cork factories to-day, greatly facilitating the drying, which is done
mostly by the atmosphere. This is all there is to the mechanical part,
but curiosity prompts us to inquire what chemicals are used to clean the
corks, so I have ascertained the principal ones, but of course every
manufacturer will have his own way of doing this part of the work,
although the principle remains the same. An old way was to wash them in
water containing chloride of tin or oxalic acid and then subjecting them
to the fumes of burning sulphur, but the sulphur bleach has been
discontinued. Bioxalate of potash has also been used in solution, as
also chloride of lime, ammonia and sulphuric acid. Another way is to
wash in a 10 per cent solution of hydrochloric acid and then immerse in
a solution of sodium hyposulphate and hydrochloric acid, finally washing
with a solution of soda and water. All of these produce the desired
effect when mere cleaning and bleaching is all that is required: but in
the poorer grade of cork, mostly a thick cork that has been jaspered or
contains micro-organisms, a system of treatment with formol or methylal,
ethyl alcohol or spirit wine and formaldehyde and impregnating with
casein has been used. These bleaches are applied to regular stoppers and
disks alike, but in addition to this the disks are given a bath of hot
paraffin, or glycerine and paraffin, which improves their resistance and
retards discoloration. This generally being done in a steam-jacketed
kettle, or tumbling barrel, and then placed in a centrifugal to remove
the excess of water and paraffin.

In some factories, and when the customer requests it, the name is
branded upon the stopper by irons heated by gas, gasolene or in a coal
fire, automatic gas heated machines being most general.

In the foregoing it has been shown how the stopper and disk are made,
and although there are many different manufacturers of corkwood
stoppers, it will be found that the _modus operandi_ just described is
followed generally, with perhaps a variation in the details. The waste
material, “recortes” as stated is collected and used in various ways,
but either in conjunction with other materials or alone in a granulated
or powdered state.

The following chapter will enumerate the three principal uses of waste
corkwood, and as these cover the fundamentals of the other uses it will
not be necessary to describe them, e.g., linoleum, made by mixing
cork-flour and linseed oil.


In giving the processes of the methods used in the conversion of the
corkwood waste and virgin corkwood, which is classed as waste, it will
not be possible to go too far into the details, as most of them are
secret, and in justice to those who use them a résumé is all that will
be incorporated in this monograph. But this will give a good idea and
understanding of the utilization, which is all that is intended. As in
the first processes of corkwood manipulation the best is taken first;
so, in the department of waste utilization, a process is now used
whereby the best scrap is made into cork disks for the Crown seal as
described, and serves its purpose well.

This scrap is taken and granulated in an iron rotary cutter mill, to a
degree of fineness that will pass a 1/8″ mesh, it is then screened and
mixed with a secret binder that has a wonderful holding quality; it is
then dried by steam and pressed into sheets by hydraulic presses, dried
again, and then stamped out in the usual manner. There is no waste to
this process as the unused portions go back to the grinders again and
through the usual process.

Granulated cork is made by grinding the waste in ordinary metal roller,
cage or bur mills, and then screening same for the various degrees of
fineness; if cork-flour is desired, a tube mill may be used.

These two uses are generally confined to the best scrap, but there still
remains a large quantity which has a great value. A portion of this is
made into Spanish black by carbonizing same in a closed iron kettle, or
retort, and then grinding same in a regulation ball mill, until the
desired fineness is obtained; this process producing a very fine black.

The above uses in no degree exhaust the amount of scrap corkwood that
leaves the various factories here and abroad, nor is its usefulness
expended, for there is one use to which cork scrap is being put that
bids fair to rival the stopper industry in importance, and that is in
the form of cork-board for insulating purposes.

The processes for the making of cork-board differ in many ways, widely
divergent in principle. The corkwood waste and virgin cork are broken up
and chipped in an ordinary iron mill as a preliminary to all processes;
in one, claimed to be the best, this chipped material is poured into
iron molds the desired shape of the slab, subjected to heavy pressure
and run into an oven kept at about 800 to 900 degrees Fahrenheit. This
oven, being a low brick type, resembling a lear and heated by coal
fires, the slab molds being drawn through on an endless chain, which
runs at a speed to keep the cork in just long enough, for the resin in
same to exude and bind the little particles together; the cork is also
charred in this process, thereby converting it into a carbonized
cellulose which makes it an excellent material for insulation.
Steam-heated hydraulic presses are also used for making small tile,
etc., being the same principle as above, without the charring.

The other process involves the use of tar, pitch or asphaltum, as a
binder for the cork particles, and in one, the cork is mixed with a clay
before being mixed with the asphaltum. The binder being heated in steam
jacketed kettles, and in one it is mixed in the proportion of one to
four, while in the other it is forced into the mass under pressure and
then drawn out again by vacuum, both mixtures being poured into molds of
the desired shape of the slab or in large molds, to be cut up after, and
subjected to heavy pressure, the sawing being done by an ordinary
rip-saw, cutting the block into any desired thickness of slab.

The above described processes do not include all of the various
manipulations of corkwood, for there are innumerable things as stated
under the “Uses” for which there is a necessity of mechanical operation,
in their making; but the general processes are as stated and will cover
most all.


The cork stopper industry had its permanent origin in Spain, in the
Province of Gerona, town of Llacostera, towards the latter part of 1750
and was contemporaneous with the inception of the glass bottle, although
corkwood was used many years before as a stopper for amphora, etc., as
noted in a previous chapter.

The trade flourished there until wars and schisms rent the country and
drove the industry to the mountains. There it slumbered and struggled
for many years until the peace was restored and the people assured that
the dangers were passed. Its revival was not very sudden, but slowly and
surely it grew, and won itself a place in the trade life of Spain and
finally became a necessity, so much so, that it began to attract
attention and other countries sought to secure the secret. About 1828
the French agents at Catalonia found enough information to warrant them
returning to France and there set up for themselves, the rivalry between
the two becoming very keen, causing much excitement among the Spanish
manufacturers; for up to that time they monopolized the trade and had a
nice time of it. This lasted until 1849, when the trade assumed such
proportions that both had all they could attend to and more. This
insured a steady increase of the trade, and before long it assumed
proportions that has surpassed the dreams of its founders. The industry
spread until the raw material began to show a shortage due to the heavy
demands made upon it. More frequent cuttings were compulsory to supply
the market, and in consequence the grade became poorer.

The realization of this caused the Spanish Government to step in and
protect the forests as a national necessity, and the result was the
passing of laws to govern the cutting of corkwood from the trees. But
the trade kept on growing in other countries and the raw stock was in
great demand.

The result of the heavy exportation of corkwood again caused some
notable alarm among the manufacturers and trades-workers in Spain and
Portugal, but principally in the former, as most of the largest factories
are located in its cities; so that the principal representatives of the
cork industry convened at Madrid in December of 1911, at which
convention resolutions were passed to urge upon the Government the
necessity of imposing an export tax or duty on corkwood ranging from
five to fifty gold pesetas ($.0965 to $9.65) per 100 kilos (220 pounds).
By so doing it was thought to remedy the shortage in the home market.

The competition between the foreign and Spanish buyers for the raw
corkwood output was largely in favor of the foreigner in 1911, owing to
the unprotective export duties, and the result has been that the once
flourishing national industry is now very badly handicapped for want of
working material.

So simultaneously with the tariff revision, which went into effect on
January 1, 1912, an endeavor was made to put in force the increase on
export corkwood, but owing to the efforts of the American cork
manufacturers, who have a great influence over the Spanish cork
industry, the proposed increase did not meet with the desired success.

In the attempt to restrict the importation of raw material the Spaniards
have failed, for its usefulness makes the demand too great and the
foreigners have invaded the Iberian Peninsula and are now buying up even
the raw stock on the trees. The corkwood markets are no longer confined
to two or three, but extend round the world, the principal ones being:
London, Paris, Rheims, Epernay, Maguncia, Dresden, New York, Pittsburgh,
San Francisco, Buenos Ayres, Calcutta, Sydney, Melbourne and Yeddo. So
it will be seen that a great demand is being made upon the forests,
which must be cultivated for increased growth and production or an early
investigation made for the growing of the trees in other countries.

Of course the industry remains very strong throughout Spain and
Portugal, and particularly in the Andalusia District of Spain, where the
manufacturing establishments play an important part in converting the
corkwood into useful articles of commerce. The Spanish yield of raw
material has remained slightly behind Portugal, but this does not affect
the former’s influence in the trade. (See Appendix.)

It is inevitable that the greatest bulk of the trade should center
around the countries in which the raw material is grown, for the
greatest advantage is thus gained by those, so fortunate in their

But the spread of the corkwood’s fame has aroused others to action, and
it appears as though the monopoly will suffer because of that fame. The
demand grows daily, and the rapid growth of the American trade bids fair
to being a very close rival to the long-established European
manufactures at least.

The waste is rapidly assuming great importance and to this the newer
entrant in the business is turning all his energy. The doctrine of
conservation and utilization has been heeded by the corkwood industry
and the waste is no longer such, rather standing as a cork product
second only to the stopper, when the fact is considered that the grower
or farmer receives about $58 per ton for raw corkwood and the waste
sells from $22 to $32 per ton; its value is apparent.

A notable feature of the shipments from Spain is the waste and shavings,
which doubled from 1906 to 1910, viz.:

  1906 — 14,624 tons
  1907 — 17,557  “
  1908 — 12,201  “
  1909 — 20,198  “
  1910 — 29,257  “

The uses to which corkwood may be put are unlimited, and as has been
seen the uses already known are sufficient, in themselves, to make it a
very important commodity. And yet when we speak of uses it is only those
that have developed by reason of the corkwood’s own peculiarity that
makes it the subject of discussion, and not the great number that it has
been adapted to, for perhaps its utility will have no end, and in my
estimation its particular qualities are but little appreciated. Of
course its application as a stopper is ideal for that purpose, but it
appears most certain that this wonderful growth is designed to be of
greater service to man than the mere function of filling the neck of a
bottle. Chemically, I think it has possibilities; the ancients found it
useful in Materia Medica, and there may still be a use in this line. At
any rate, it is the most wonderful bark of its kind, its service has
been a long one, and its benefits, even as a stopper, have been many. A
wonderful material truly, and of interest, so full that it seems I have
failed to do it justice in these few words presented in my endeavor to
describe the Quercus Suber of Linnæus.


For those who may be interested in a few statistics of the trade is
appended the following figures relating to the Spanish and American


There were 892 factories throughout Spain in 1912, in 107 towns and
cities, divided as follows:

  Seville District       305 in 48 towns
  Barcelona District     507 in 31   “
  Other Districts         80 in 28   “

These factories employ approximately 40,000 people in the various
branches of the industry at an average daily wage of 67 cents.

The raw material yield for 1912 is reported as: 7800 short tons, valued
at $57.90 per ton to the grower, or $4,516,200.

It will also be of interest to show a few comparisons of values, for
various years, in shipments to foreign parts, viz.:

           Description         │    Pounds    │    Value
  Cork in sheets ............. │  11,009,939  │   $405,366
  Cork squares ............... │   1,180,489  │    265,610
  Corks ...................... │  11,960,760  │  4,870,948
  Cork shavings .............. │  66,435,426  │    363,563
  Other manufactured cork .... │     864,820  │     40,656
                               │  ──────────  │ ──────────
    Total .................... │  91,451,434  │ $5,946,143
                               │              │

           Description         │    Pounds    │    Value
  Cork in sheets ............. │  16,798,492  │   $618,489
  Cork squares ............... │   2,055,865  │    462,472
  Corks ...................... │  14,924,052  │  6,105,294
  Cork shavings .............. │  64,367,448  │    526,642
  Other manufactured cork .... │   1,190,789  │     57,382
                               │   ─────────  │ ──────────
    Total .................... │  99,336,646  │ $7,770,279
  Corrected figures showing    │              │
    totals as ................ │ 109,336,646  │ $7,942,677
                               │              │

           Description         │    Pounds    │    Value
  Cork in sheets ............. │  21,564,347  │   $741,029
  Cork squares ............... │   2,076,881  │    467,298
  Corks ...................... │  17,817,037  │  7,288,787
  Cork waste ................. │  73,510,473  │    591,468
  Cork, manufactured in        │              │
    other forms .............. │   1,828,030  │     89,723
                               │ ───────────  │  ─────────
    Total .................... │ 116,796,768  │ $9,178,305
                               │              │

           Description         │    Pounds    │    Value
  Corkwood ................... │  17,928,000  │   $528,810
  Cork squares ............... │   1,492,000  │    356,229
  Corks mfrd.}                 │              │ {7,864,299
  Cork waste } ............... │ 100,396,000  │ {  754,848
  Other mfrs.................. │   1,166,000  │     49,783
                               │ ───────────  │ ──────────
                               │ 120,982,000  │ $9,553,969
                               │              │

The following is a comparison of the first six months of 1909, 1910
and 1911.

            Articles           │   Tons   │   Value
  Corkwood ................... │  1,686   │  $158,644
  Cork squares ............... │    262   │   129,646
  Corks ...................... │  2,624   │ 2,361,620
  Cork waste and shavings .... │  9,589   │   172,604
  Cork, other manufactures ... │    211   │    25,987
                               │          │

     Articles                  │   Tons   │  Value
  Corkwood ................... │  3,157   │  $255,718
  Cork squares ............... │    485   │   240,057
  Corks ...................... │  3,629   │ 3,265,760
  Cork waste and shavings .... │ 13,935   │   205,822
  Cork, other manufactures ... │    251   │    27,133
                               │          │

  Articles                     │   Tons   │  Value
  Corkwood ................... │  5,129   │  $415,432
  Cork squares ............... │    442   │   218,755
  Corks ...................... │  4,057   │ 3,669,075
  Cork waste and shavings .... │ 18,143   │   326,573
  Cork, other manufactures ... │    248   │    32,657
                               │          │

The statistics showing the shipments to various countries are for 1909:

                │        │     │      │Cork  │Cork │
                │        │     │      │Waste │ in  │
   Countries    │Corkwood│Cork │Corks │ and  │Other│  Total
                │        │Sqs. │      │Shav. │Forms│
                │  Tons  │Tons │ Tons │ Tons │Tons │  Tons
  United States │  2,065 │  —  │  158 │ 7,594│ 280 │ 10,097
  Great Britain │    842 │   4 │1,094 │ 7,539│  38 │  9,518
  Germany ......│      5 │  18 │  715 │ 4,555│  —  │  5,293
  France .......│  1,256 │ 276 │2,044 │   189│  56 │  3,821
  Italy ........│      6 │  79 │  435 │    11│  —  │    532
  Belgium ......│    164 │  —  │  136 │   215│  11 │    526
  Russia .......│    463 │  —  │    1 │    — │  —  │    464
  Aust─Hungary  │     —  │  30 │  346 │    — │  —  │    376
  Argentina ....│    164 │ 123 │   57 │    — │  —  │    344
  Other ........│     40 │   7 │  426 │    95│   9 │    575
  Total ........│  5,005 │ 537 │5,412 │20,198│ 394 │ 31,546
                │        │     │      │      │     │


In 1899, there were 62 factories in the United States of varying sizes
and located in the following states: New York (Brooklyn), Pennsylvania,
New Jersey, Illinois, Massachusetts, Rhode Island, Wisconsin and Ohio.
Employing 2340 wage earners. Importing a raw stock of $2,404,000, and
making products valued at $4,392,000.

In 1904, the factories decreased to 50 in number, the wage earners
increased to 2895, the imported raw material to $2,459,197 and the
products to $4,490,952.

In 1909, the factories increasing again to 62 in number, the wage
earners to 3142, the imported raw material to $3,435,000 and the
products to $5,940,000: corks selling from 3 cents to 40 cents per

This of course does not appear to be a very extensive business, but the
nature of the commodity will readily convince that the money figures are
not at all in comparison to the bulk of corkwood, for it would really
seem that if the trade should increase to an amount sufficient to vie
with other prominent ones, the ships would be at loss how to stow the
other freight. The imports of corkwood into this country and the
exports, for comparison, may be seen in the following tables:


           January         │      Seven Months ending January
      1912         1913    │     1911         1912         1913
  Corkwood, Free:          │
    $450,082     $367,884  │  $2,265,373   $1,849,550   $1,707,164
  Corks mfrd., Dutiable:   │
    $181,252      130,580  │   1,380,109    1,137,504    1,180,816


                                         │ Seven Months ending
                            January      │      January
                          1912    1913   │   1912      1913
  Corkwood, Free:        $1,518  $1,195  │  $19,795   $22,393
  Corks mfrd., Dutiable:    209   1,086  │    3,078     2,170

And the periods ending December, 1913 will be of interest also.


          December         │     Twelve Months ending December
      1912         1913    │     1911         1912         1913
  Corkwood, Free:          │
    $300,253     $468,937  │  $3,819,651   $3,182,131   $3,616,177
  Corks mfrd., Dutiable:   │
    $164,711      194,457  │   2,070,672    2,440,399    2,370,527


                                         │Twelve Months ending
                           December      │      December
                          1912    1913   │   1912      1913
  Corkwood, Free:        $2,960     —    │  $34,404   $25,091
  Corks mfrd., Dutiable:    —    $8,335  │    5,552     5,392


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    Translated from the German by Charles Salter. 8vo. cloth. 262 pp.
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  =—— Utilization of Waste Products.= A treatise on the rational
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  =KREMANN, R. The Application of Physico-chemical Theory to Technical
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  │                        TRANSCRIBER’S NOTES                         │
  │                                                                    │
  │ * Page numbers referenced herein are those in the original work    │
  │   and are for information. Actual location may be found by         │
  │   searching for the relevant text.                                 │
  │ * Contents: “Quercus Liber” appears in Contents as a chapter but   │
  │   is typeset in the original work (page 5) as a section. The       │
  │   original work formatting has been retained.                      │
  │ * Contents: “The Tree and Growth” appears in Contents as a         │
  │   chapter but is typeset in the original work (page 12) as a       │
  │   section. The original work formatting has been retained.         │
  │ * Contents: “Substitutes” appears in Contents as a chapter but     │
  │   is typeset in the original work (page 53) as a section. The      │
  │   original work formatting has been retained.                      │
  │ * Contents: “Waste utilization” appears in Contents as a section   │
  │   but is typeset in the original work (page 68) as a chapter. The  │
  │   original work formatting has been retained.                      │
  │ * Page 5: Vaniçek may be misspelled.                               │
  │ * Page 6: Grammatic may be misspelled.                             │
  │ * Page 32, molecular structure diagram: The right-hand CH_{2}      │
  │   groups should be connected.                                      │
  │ * Footnote 21: “Etymology of Word” is not found in the original    │
  │   work. The chapter in Contents entitled “Quercus Liber (Linnæus)” │
  │   et seq. gives the etymology.                                     │
  │ * Unmatched quotation marks have been retained. The original work  │
  │   text is shown below in curly brackets, { }, for clarity.         │
  │   * Page 22: The closing quotation mark for {Again, “It is         │
  │     produced} was not found.                                       │
  │   * Page 41: The quotation mark at {July 1666” After} is           │
  │     apparently used to set off the date from the diary entry. The  │
  │     closing quotation mark for the diary entry is at {junts (old   │
  │     cable),” but}.                                                 │
  │   * Page 43: The opening quotation mark for {the British Museum.”} │
  │     was not found.                                                 │
  │   * Page 43: The closing quotation mark for {“The various          │
  │     applications} is possibly at {blacks known in painting.”}      │
  │     on page 53. Otherwise, both quotation marks are likely         │
  │     unmatched.                                                     │
  │   * Page 53: The closing quotation mark for {results. “A           │
  │     primitive material} was not found definitively but possibly    │
  │     could be located immediately after {the elements of cork.}     │
  │     on page 54.                                                    │
  │ * This work has been preserved as in the original, including       │
  │   archaic and inconsistent spelling, punctuation and grammar,      │
  │   except as noted below.                                           │
  │ * Changes made to the main text:                                   │
  │   * Preface: ‘(Linneus)’ changed to ‘(Linnæus)’.                   │
  │   * Page 5: ‘Etymologische Worterbuch’ changed to ‘Etymologisches  │
  │     Wörterbuch’.                                                   │
  │   * Page 8: ‘korkeiche’ changed to ‘Korkeiche’.                    │
  │   * Page 11: ‘Farenheit’ changed to ‘Fahrenheit’.                  │
  │   * Page 16: ‘tree iself, which’ changed to ‘tree itself, which’.  │
  │   * Page 32: ‘Cyclohaptanone’ changed to ‘Cycloheptanone’.         │
  │   * Page 36: ‘7/16’ changed to ‘7/16″’.                            │
  │   * Page 54: ‘actetone’ changed to ‘acetone’.                      │
  │   * Page 55: The cork manufacturing chart moved from within        │
  │     the paragraph to immediately below the paragraph.              │
  │   * Page 69: ‘insultaing’ changed to ‘insulating’.                 │
  │   * Page 75: The table for waste and shavings changed from two     │
  │     columns to one column.                                         │
  │   * Footnote 25: ‘“m” signifying metal’ changed to ‘“M”            │
  │     signifying metal’.                                             │
  │ * Changes made to “A SELECTED LIST OF BOOKS ON CHEMISTRY AND       │
  │   CHEMICAL TECHNOLOGY”                                             │
  │   * Page 4, Church's Laboratory Guide: ‘cloth,’ changed to         │
  │     ‘cloth.’                                                       │
  │   * Page 10, Olsen: ‘cloth.,’ changed to ‘cloth.’                  │
  │                                                                    │

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