Blackening Zinc Plates.

Practical Magazine 22, 1876

(Chemistry applied to the Arts, Manufactures, &c.)

The mode of producing a liquid for blackening zinc plates, simplified and recommended by PUSCHER, consists in dissolving equal parts of chlorate of potash and sulphate of copper in 36 parts of water. If the zinc plate, after being scoured bright with diluted muriatic acid and fine quartz sand, is put into the solution for only a few moments, it is covered with a velvety-black coating, adhering very slightly. If it is then quickly and superficially washed with water, left to dry, and then immersed in a dilute solution of asphalte in benzole, the superfluous liquid thrown off, and the plate finally rubbed, after drying, with a pad of cotton wool, to fix the black colour, a zinc plate is obtained which can be highly recommended for roofing and similar purposes.

- Deutsch.-Amer. Ind. w. Gew.-Zeit., through Der Metallarbeiter.

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