TANNING MATERIALS 



TANNING MATERIALS 



625 



outer bark. Other pine barks contain 2 to 7 per cent of 

 tannin. 



Sitka spruce (Picea Sitchensis) is native along the coast 

 from Alaska to northern California. The bark contains 

 about 17 per cent of tannin. 



Norway spruce (Picea excelsa). The bark contains 7 to 

 13 per cent of catechol tannin and much fermentable 

 sugar. It is used largely in Austria and is the source of the 

 so-called larch bark extract. White spruce (P. alba), native 

 in northern United States and Canada, is very similar. 



Silver fir (Abies pectinata) is used to a limited extent. 

 The bark contains 6 to 15 per cent of iron-bluing tannin. 



Lowland fir (.Abies grandis) is native along the coast 

 from Vancouver island to northern California, and Inland 

 to Idaho and Montana. The bark contains about 9 per 

 cent of tannin. 



Larch (Larix Europcea) contains 9 to 10 per cent of a 

 pale catechol tannin and is suitable for light leathers. 



Dwarf juniper (Juniperus communis) bark is used in 

 Russia. Several members of the Taxaceae or yews are 

 used in Australasia for tanning and contain 20 to 30 per 

 cent of tannin. 



Redwood (Sequoia sempervirens) is native along the 

 coast and thirty miles inland from southern Oregon to 

 south of Punta Gorda, California. The wood contains 

 about 2 per cent of tannin and the bark probably some- 

 what more. 



Big tree (Sequoia gigantea) produces a gum which 

 exudes from the tree and which may contain as high 

 as 70 per cent of tannin. 



The oak tannins. 



Chesnut oak (Quercus Prinus) is found from southern 

 Maine to Maryland and in the mountains southward to 

 northern Alabama and Georgia, and westward to Lake 

 Erie and central Kentucky and Tennessee. Chestnut oak 

 bark is next in importance to hemlock bark in this 

 country, and contains 8 to 14 per cent of tannin, probably 

 both catechol and pyrogallol. The wood contains 2 to 5 

 per cent of tannin. An extract is also made from the 

 bark. It is customary to cut all trees when the sap is 

 rising if the bark is to be used, as it can be most easily 

 peeled at this time. All barks should be carefully piled in 

 the woods as peeled, as otherwise there is considerable loss 

 of tannin from exposure to the weather. The quantity of 

 oak bark used in 1905 was 422,000 cords, valued at 

 .$3,765,000 ; in addition, 214,000 barrels of extract, valued 

 at $2,300,000, was also used. 



Tanbark oak (Quercus densiflora) is found in southern 

 Oregon and southward to Mariposa county, California. 

 The tree is also known locally as chestnut oak. The bark 

 contains 9 to 22 per cent of tannin and averages about 18 

 per cent. The foliage and twigs contain about 5 per cent 

 of tannin. 



The barks of other American oaks contain considerable 

 tannin. White oak (Quercus alba) contains 3 to 9 per cent; 

 red oak (Q. rubra), 3 to 5 per cent ; black oak (Q. nigra), 

 largely used as a source of quercitron, a dyestuff, but of 

 little value for tanning ; California black oak (Q. Cali- 

 fornica), about 10 per cent of tannin ; Highland oak (Q. 

 Wislizeni), about 7 per cent ; California white oak (Q. 

 lobata), about 12 per cent ; Canyon live-oak (Q. chryso- 

 lepis), about 10 per cent ; Pacific post oak (Q. Garryana), 

 about 8 per cent. 



Other oak barks used largely abroad are the following : 

 English oak (Quercus peduneulata), common in Eng- 

 land, Ireland, Scotland and Slavonia. It is used for 

 making oakwood extract. The bark contains 8-15 per 

 cent of tannin. Q. sessilifiora, the bark of which con- 

 tains 10-14 per cent of tanning matter, possibly both 

 catechol and pyrogallol groups. The yield of tannin is 

 less from trees over twenty-five years of age, and cop- 

 pice barks, from absence of ross, are often strong, and 



B40 



also contain less coloring matter and more fermentable 

 sugar. Oakwood contains only a very small percentage 

 (2-4 per cent)- of tannin, practically identical with that 

 of chestnut. Turkey oak (Q. Cerris), of southern Europe ; 

 Q. pubescens, in mountain districts and scattered in souths 

 ern Europe, 8-15 per cent of tannin ; Evergreen oak (Q. 

 Ilex), south Europe and Algeria, 5-11 per cent of dark 

 colored tannin, well adapted to sole leather ; cork oak 

 (Q. Suber), the outer bark of which is cork ; the interior 

 bark contains 12-15 per cent of tannin, which is redder 

 than that of ordinary oak ; African oak (Q. pseudosuber), 

 of Algeria, 10-14 per cent of tannin ; Q. Mirbecki, of 

 Algeria, 8 per cent of tannin in the bark ; Q. Toza, 

 of the Pyrenees and south France, 14 per cent of tannin 

 in the bark ; Kermes oak (Q. coccifera), of south Europe 

 and Algeria, has an average of 10-18 per cent of tannin, 

 giving a firm, dark, sole leather. 



Valonia (from Quercus JEgilops and probably other 

 species, Q. macrolepis, Grceca, TJngeri, coccifera), is the 

 commercial name of the acorn cups of these several kinds 

 of oaks. Best Smyrna valonia contains up to 40 per cent, 

 Greek 19-30 per cent, Candia valonias up to 41 per cent, 

 and Caramanian 17-22 per cent of pyrogallol tannins or 

 pyrogallol derivatives, and deposit a great deal of bloom 

 consisting of ellagic acid. The acorn contains a considerable 

 amount of fermentable sugar and but little tannin. Valo- 

 nia is hand-picked in three grades. The beard sometimes 

 contains over 40 per cent of tannin. Valonia is especially 

 suitable for the manufacture of sole-leather. It deposits 

 much bloom, and is used as a dusting material. It makes 

 the leather solid and compact, but leaves the grain some- 

 what rough and hard to work. In mixture with gambler 

 and other materials, as it is generally used, it is an excel- 

 lent tannin for dressing leather, and with proper manage- 

 ment deposits little or no bloom. 



"Nut galls" is the term applied to the excrescences 

 on plants produced by insects for the purpose of deposit- 

 ing their eggs. "Turkish" or Aleppo galls, from Q. in- 

 fectoria, are developed from the young shoot of the oak, 

 and are best before ^^^^ 



the insect has escaped, "'''^^tl^^li'li 



as they contain in this /^mMilmm 



stage up to 50 or 60 /^:^'^^ 



per cent of gallotannic ' ' ^ 



acid. These galls and 

 those of Rhus semia- 

 lata are the principal 

 sources of the pure 

 tannin of commerce. 

 Q. infectoria also 

 bears a large gall like 

 an apple, called "Ap- 

 ples of Sodom," or , , , 

 " rove," caused by a ^^ 

 different insect, which 

 contains 24-34 per 

 cent of gallotannic 

 acid. 



Knoppem are galls 

 produced on the im- 

 mature acorns of vari- 

 ous species of oaks, 

 principally Quercus 

 Cerrisin Hungary,and 

 contain up to 35 per cent of gallotannic acid. Like all 

 purely gallotannic materials, they naturally give a soft 

 and porous tannin, ill-adapted for sole leather. 



The bark of a number of Indian oaks yields tannin, Q. 

 incana containing about 22 per cent. 



The chestnuts. 



Chestnut (Castanea Americana, Pig. 849) is native 

 from southern Maine and Ontario to Delaware, Maryland, 



Fig. 849. Chestnut bark and foliage. 



