The first class includes those tannins which are the results of
perfectly natural or normal growth, and a growth necessary to the
development of vegetation, for instance, bark, sumac, etc., whereas
the second class contains those which are the results of abnormal
growth, caused by diseases, stings of insects, etc. An example of this
is the gall. Both of these classes are used to a great extent in
Europe, while only the first division is in general use in the United
States. We will first consider the physiological tannins.
_Oak Bark._--This material was, is, and will be for some time to come
the main tanning material in use here in Europe. The advantages of the
oak tannage are as fully appreciated here as in the United States. The
European oak gives a light colored, firm leather, with good weight
results, is comparatively cheap and of an excellent quality. The
varieties are numerous, each country having its own kind. Those in
most general use are:
_Spiegel Rinde_ (mirror bark).--This bark is well distributed
throughout Europe, and is peeled when the tree has attained a growth
of from 12 to 24 years. It is marketed in three grades.
_Reitel Rinde_--Is obtained from the same tree as the spiegel rinde,
but after the tree has attained a growth of from 25 to 40 years.
_Alte Pische_ (old oak).--Obtained from the aged tree. It is not as
valuable as the younger bark, and consequently brings a much lower
price.
Spiegel rinde may be judged by small warts which appear on the shining
surface of the bark. The presence of a great number of these, as a
rule, indicates a high tannin percentage.
Bosnia has fine oak trees, the bark containing 10 to 11 per cent.
tannin.
Bohemia has the _trauben eiche_ (grape oak).
France uses the kirmess oak, which grows in the south of that country
and in northern Africa. Two grades are made, viz., root and trunk.
Tyrol has the evergreen oak--12 to 13 per cent. tannin.
Sardinia possesses a cork oak, which yields 13 to 14 per cent.
White oak is found throughout Europe, yielding 10 per cent. The price
of oak bark varies a great deal. The assortment is much more strict
than in the United States. In Austria it brings 4 to 5 fl., equal to
$1.60 to $2 per kilo. (224 lb.); in Germany, 11 to 16 marks per 100
kilos.[1]
[Footnote 1: In the principal districts in America, removed from the
cities, the price of oak bark is about $4 to $6 per cord or per ton
of 2,240 lb. The hemlock bark, which gives a sole leather just as
thoroughly tanned, but of a darker and reddish color, costs the
larger tanners from $3 to $4 a cord.]
The above mentioned varieties are all used for both upper and sole
leather. In Germany a great deal of upper leather is pure oak tannage,
but one seldom finds a pure oak tanned sole leather; it is almost
always in combination with other tannics.
_Pine Bark_--Is well distributed and is a very important tanning
material. It bears the same relation to oak bark here as does hemlock
in America, but its effects are quite different from hemlock. The best
Austrian sorts are those of Styria and Bohemia, but that of Karuthen
is also of good quality. The German pine comes from Thuringia to a
great extent. The countries that consume the greatest amount of pine
bark are Austria, Germany, Russia and Italy. The tannin contained
varies from 5 to 16 per cent. Its use is almost wholly confined to the
handlers, as its weight returns are not so satisfactory as oak or
valonia. In case it should be used for layers it is always in
combination with some better weight-giving tannic. For upper leather
its use is limited.
The bark is always peeled from the felled tree, and often the woodman
accepts the bark in part payment for his labor; he then sells the bark
to the tanner or agents who go about the country collecting bark. It
is generally very nicely cleaned. I would here like to correct a
mistake which tanners often make in their estimations of the value of
barks. A tanner usually buys the bark of southern-grown trees in
preference to that of trees grown in northern countries, as it is a
common idea that southern vegetation contains more tannin than that of
the north. This is a fallacy, as has not only been proved by careful
analyses, but may also be found to be an incorrect conclusion after a
moments' thought. Those trees which flourish in southern countries
grow very rapidly, and as tannin is necessary to the development of
leaf structure, etc., it is absorbed to a greater extent than is the
case with the slower-growing tree of the north. The tannin contained
in the sap does not increase in the same ratio as does the rapid
growth, and it follows that the remainder in the bark is less than in
the tree of slower growth.
_Birch Bark_--Is at home in Russia, Norway, and Sweden. It is used for
both upper and sole leather, but seldom alone. The bark is usually
peeled from the full grown tree, and contains 4 to 9 per cent. tannin.
_Willow Bark_--May also be found in the above mentioned countries and
also in Germany. This material is used for both upper and sole
leather, and contains 6 to 9 per cent. tannin. It is a very delicate
material to use, as its tannin decomposes rapidly.
_Erlen Rinde_--Is also a native of Germany, but is not used to any
great extent. The same may be said of the larch, although this variety
is also to be met with in Russia.
_Mimosa Bark_--Is obtained from the acacia of Australia. It is a
favorite in England. The varieties are as follows: Gold wattle, silver
wattle (blackwood, lightwood), black wattle, green wattle. The gold
wattle is a native of Victoria. Its cultivation was tried as an
experiment in Algeria and met with some success. The trees are always
grown from seeds. These seeds are laid in warm water for a few hours
before sowing. The acacia may be peeled at eight years' growth and
carries seeds. The Tasmania bark is very good; that from Adelaide
likewise good.
Sydney does not produce so good an article, but Queensland better. The
bark is marketed in the stick, ground or chopped.
Madagascar and the Reunion Islands have also a mimosa bark.
The mimosa barks give a reddish colored leather, pump well and contain
a high tannin percentage, 10 to 35 per cent.
Now we will consider the fruit tanning materials.
Valonia may truly be called one of the most generally used tanning
agents at present employed in Europe. All countries consume it more or
less. Valonia was first used in England about the beginning of this
century. A few years later Germany began using it, and still later
Austria introduced it. It is the fruit of the oak tree and is
obtainable in Asia Minor and the adjacent islands. In form it
resembles the American acorn, but in size it nearly trebles it. The
fruit may be divided into two parts, namely, the cup and acorn, and
the cup again divided into trillor and inner cup. The acorn only
contains 10 per cent. tannin, whereas the cup contains from 25 to 40
per cent.
The percentage depends altogether upon the time of harvesting and the
place of growth. The best valonia is derived from Smyrna, and is
naturally the highest priced article. Valonia is worth from 22 to 28
florins ($9 to $11) per 100 kilos. (224 pounds) at present. The other
provinces and islands from which it is obtainable are Demergick,
Govalia, Idem, Ivalzick, Troy (this is the best); Metelino Island, the
vicinity of Smyrna. The material sold in three grades--prime, mazzano;
seconds, una aqua; thirds, skart.
The product of Smyrna generally averages:
Tons. Price.
Prime. 2,000 to 3,000 28 florins.
Seconds. 5,000 to 10,000 25 "
Thirds. 20,000 to 30,000 22 "
The _Metilino_ valonia is a product of a neighboring island, and is a
very good article. It may be easily distinguished by its thin cup. It
is harvested in September.
The _Candia_ valonia is nearly as long as it is wide, in contrast to
the Smyrna, which is much wider than long. The recent harvest showed a
return of 800 to 1,000 tons, but no assortment is made. A grade called
the Erstlige is sold, this being the first which has fallen to the
ground before maturing.
A peculiarity of the valonia is that it often strikes out a sort of
sugar sweat, which gives the cup a less attractive appearance, but
denotes the presence of large quantities of tannin.
Valonia is used almost wholly for sole leather, either alone or in
combination with pine or oak bark or knoppern and myrabolams. The
union of valonia and knoppern is that in most general use. Valonia
gives the leather a yellowish appearance, as it deposits a great deal
of yellow bloom. The leather is very firm and of good wearing
qualities. The weight results are also excellent, as will be seen
below. To sole leather there are usually given from one to three
layers of valonia. The demand for valonia is increasing more and more
every year, and the present outlook does not indicate any relaxation
of its popularity. Its use for upper leather is very limited.
Myrabolams are mainly used in England and Austria, and give a nice
light-colored leather, both upper and sole, although rarely used
alone. Their main use is for dyeing purposes. They are indigenous to
the East Indies.
Sumac is so well known that treating of it is superfluous. Its use is
very extensive, and it is a general favorite for light, fine leather,
which is mostly used for colors.
_Gambier_--Is in general use in England and to some extent in Germany.
_Catechu_.--Obtained from India, resembles gambier greatly. Its use is
almost wholly confined to England. It is also consumed by the silk
manufacturers in preference to gambier, for weighting purposes.