Coloured Cements fit for Grinding and Polishing.

Practical Magazine 22, 1876

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

Dr. S---ky's coloured cements are used to ggive cast goods of zinc or brass the appearance of buhlwork, and to fill up the holes made by etching in zinc door-plates, street numbers, coats of arms, &c. They are also with advantage employed for making casting-models of more artistic objects, as well as for mosaics on metal ground; but they may further be found useful in engineering works for isolators, larger rings and plates. According to Stach, the following procedure is necessary in their preparation: - A solution of soluble glass of 33° Réau. is mixed with fine whitening, with the addition of the materials mentioned below, until it assumes the tenacity of a thick plastic mass, and thus different coloured cements, hardening in six or seven hours, of considerable strength, and very useful for the purposes above quoted, are obtained. By adding grey sulphuret of antimony a black cement is obtained; this may be polished with agate, and has a metallic onyx-like lustre. Another black cement is prepared by mixing equal parts of sulphuret of antimony and iron filings (finest) with above soluble glass; but this cement can only be ground.

Carbonate of copper, pure chrome green, give green; cobalt-blue, blue cements. (Ordinary ultramarine is not fit for use, because it forms Glauber's salt and scatters the mass.) Red lead gives orange cement, sulphide of cadmium citrine, cinnabar bright red, and cochineal-lac violet cement; zinc dust and alcoholized iron give a brown cement, and powdered manganese acts in the same manner. An especially valuable grey cement, which may be polished with the agate to a metallic lustre, and used in the repair of damaged zinc ornaments — whether cast or of sheet zinc – is produced by mixing pure most finely-sifted zinc dust with soluble glass. White cement is made by mixing fine chalk and zinc-white with soluble glass. Hitherto If, instead of sugar of lead, a like quantity of sulthose mixtures have been used solely for imitating marble, but the cements are also of great value in the metalware industry.

- J. J. Hess, in Der Metalarbeiter.

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