Leather, cloth, wood and similar materials are silvered by processes similar to those used for gilding, silver leaf being substituted for gold leaf. Metals may be silvered either by brazing a thin sheet of silver to the surface, or by electro-plating. Frequently, however, it is desired to lightly silver a metal surface, such as brass or copper, so as to make any figures engraved thereon appear more distinct. Clock faces, dials and the scales of thermometers and barometers are cases in point, and if the surface be well lacquered with white lacquer after being silvered, such a coating is very durable. Silvering fluids or powders containing mercury should never be used unless the articles are to be afterwards exposed to a red heat so as to drive off the mercury. A silvering fluid which is very commonly sold to housekeepers under the name of Novargent or Plate Renovator, consists merely of nitrate of mercury or quicksilver. When rubbed on a copper cent or a brass stair-rod it gives it at once a bright silvery surface, but the brightness soon fades and the article, if brass, becomes black and dirty, while if it should be a piece of plated ware it will be ruined. Stair-rods and similar articles, if well silvered with powder No. 1, and then lacquered with good lacqner, will present a white silvery appearance for a long time. Plated goods should be re-coated by the electro-plating process.
1. Nitrate of silver, 30 grains; common salt, 30 grains; cream tartar, 200 grains. Mix. Moisten with water and rub on the article with wash leather. Gives a white silvery appearance to brass, copper, etc.
Add common salt to a solution of nitirate of silver until the silver has all been precipitated. Wash the white precipitate or chloride of silver and add a strong solution of hyposulphite of soda until the white chloride is dissolved. Mix the resulting clear liquid with pipe-clay which has been finely powdered and thoroughly washed.
3. 1 oz. of nitrate of silver dissolved in 1 quart of rain or distilled water. When thoroughly dissolved, add a few crystals of hyposulphite of soda, which will at first form a brown precipitate, but which redissolves if sufficient hyposulphite has been employed. The solution may be used by simply dipping a sponge in it, and Tubbing it over the article to be coated. A solution of gold may be made and used in the same manner.
A coating of silver, heavier than can be obtained by the above, may be given by the following process: Precipitate silver from its solution in nitric acid by means of copper. Take of this powder 1/2oz.; common salt, 2 oz.; sal ammoniac, 2 oz.; and corrosive sublimate, 1 drachm. Make into a paste with water. Having carefully cleaned the copper surface that is to be plated, boil it in a solution of tartar and alum, rub it with the above paste, heat red hot and then polish.