Dyeing of Glazed Skins.

Practical Magazine 20, 1876

(Chemistry applied to the Arts, Manufactures, &c.
Dyeing, Calico Printing, Bleaching, Tanning, and Allied Subjects.)

Glazed skins, especially those dyed brown, which, with those dyed grey, are now most in demand, are found in the most varied tints, from the brightest yellow brown to red brown and the deepest brown, but it is sufficient to know how to prepare baths for bright, medium, and deep brown, to obtain with these types all the baths of other tints. They are composed as follows: —

1. For bright brown:
-38½ gallons of water,
6½ lbs. of alder bark,
2.2 pounds of fustic,
8¾ oz. of yellow wood,
2¼ oz. of Brazil dye-wood,
1½ oz. of logwood.

2. For medium brown:
36¼ gallons of water,
4.4 lbs. yellow wood,
2.2 pounds fustic,
1¾ oz. Bablah,
8¾ oz. quercitron bark,
8¾ oz. Brazil dyewood,
4¼ oz. logwood.

3. For deep brown:
43 gallons of water,
4.4 lbs. fustic,
17½ oz. yellow wood,
8¾ oz. quercitron bark,
4¼ oz. Brazil wood,
30½ oz. logwood,
and solution of indigo carmine according to requirement.

For every 2.2 lbs. of wood, 8¾ gallons of water are taken. In the same way as with indigo carmine, yellow berries or aniline colours may be added according to the shade desired. In stead of alder bark, willow bark may be used. In many German establishments a decoction of spent fir bark is used, but in France alder is preferred, because, on account of the small quantity of tannin in its bark, the grain appears finer, softer, and more delicate. Bablah, like fir bark, is very astringent, and should not be employed without care, because it closes up very much. It is especially applied to skins with strong grain, or those which, in consequence of incomplete tanning, do not easily take colour. This is a significant example of the use of astringents as agents of fixation. These agents are useful for dyeing baths only within certain limits. If used in excess they are injurious. They give hardness to the colours on skins completely tanned, and always a rough appearance. According as one or the other of these astringents is employed, choice must be made between fustic, which is rich in tannin, and yellow wood, which is poor in it. For this reason the formula for deep brown contains only colouring woods properly so called. These woods, especially Brazil or redwood and logwood, are prescribed only in the proportion suitable for putting into the bath nothing but the necessary tannin.

- Der Gerber.

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