Page:The Art of Bookbinding, Zaehnsdorf, 1890.djvu/132

102 2. Boil a quart of vinegar with a quantity of old iron nails or steel filings for a few minutes. Keep this in a stone jar, and use the clear liquid. This can from time to time be boiled again with fresh vinegar. An old iron pot must be kept for boiling the black.

Brown.—1. Dissolve a $1/4$-lb. of salts of tartar in a quart of boiling water, and bottle it for use.

This liquid is mostly used for colouring; it has a very mellow tone, and is always used before the black when a strong or deep colour is required. It is poisonous, and must not be used too strong on the calf or it will corrode it.

2. For a plain brown dye, the green shells of walnuts may be used. They should be broken as much as possible, mixed with water, and allowed to ferment. This liquid should then be strained and bottled for use, A pinch of salt thrown in will help to keep it. This does not in any way corrode the leather, and produces the best uniform tint.

Yellow.—1. Picric acid dissolved in water forms one of the sharpest yellows. It is a pale yellow of an intense bitter taste. It must not be mixed with any alkali in a dry state, as it forms a very powerful explosive compound. It is a dangerous chemical and should be carefully used. It may be bottled for use.

2. Into a bottle put some turmeric powder, and mix well with methylated spirit; the mixture must be shaken occasionally for a few days until the whole of the colour is extracted. This is a very warm yellow, and produces a very good shade when used after salts of tartar.

For all the following, a preparation or ground of paste-water must be put on the calf, that the liquids may not sink through too much. The calf must be paste-washed all over equally, and allowed to get thoroughly dry. It will then be ready for the various methods. Perhaps to wash it over night and let it stand till next morning will