Black mordant for silver. simple recipes

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FACTORY TECHNOLOGIES AT HOME - SIMPLE RECIPES
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Black mordant for silver. Simple recipes and tips

Factory technologies - simple recipes

Directory / Factory technology at home - simple recipes

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Blackening (the so-called niello) is a widespread and almost the only practical way of coloring the surface of silver or silver-plated things, and not the entire surface of the thing is painted black, but only some of its parts in the form of various figures, patterns, arabesques, etc. This kind of decoration of silver items with niello has been known to us for a very long time: Tula silver snuff boxes and cigarette cases, Caucasian belts and daggers "under niello".

The blackening process consists in the formation or deposition of silver sulfide on the surface of a silver thing.

In a handicraft way, blackening is done chemically: deep patterns engraved on the surface of a thing are filled with a fusible composition, including silver sulfide, then the thing is exposed to a high temperature sufficient to fuse the composition with silver. That is, there is a partial coating of the surface of the thing with "black enamel", the composition of which is different for different handicraftsmen.

Here is one of the good recipes black enamel: 38 parts of silver, 72 parts of copper, 50 parts of lead, 384 parts of sulfur and 36 parts of borax are alloyed in a crucible, and the metals included in the composition turn into sulfur. After cooling, the alloy is crushed into a fine powder and carefully sieved. When used, the engraved places are sprinkled with enamel powder and the thing is kept on fire until the melted enamel fills the recesses again. After cooling, the excess enamel is washed off, the thing is ground and polished.

In large-scale industries, niello is induced mostly by galvanic means.

Sometimes silver or silver-plated things (vases, candelabra, figures) are blackened with graphite. To do this, they are lubricated with a mushy mixture of 6 parts of powdered graphite and bloodstone in powder with turpentine (bloodstone, or crocus, is native iron oxide). When the lubricant dries, the thing is wiped with a soft brush and suede, then its convex places, to give them more shine, are polished with a cloth moistened with alcohol or vodka. Such underlining is purely mechanical and is due to the same conditions that pollution of any metal surface produces over time, i.e. adhesion of dust particles (in this case, graphite plays the role of dust) to surface irregularities and roughness. Therefore, the less smooth the surface, the more successful its underlining by this mechanical method.

Such blackening, of course, is not as strong as chemical.

Author: Korolev V.A.

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