Important: Safety Warning
This page contains a formula or preparation using substances now known to be dangerously toxic, such as arsenic, mercury, lead, or cyanide compounds. Exposure to these substances can cause severe poisoning, permanent injury, or death.
In addition, this page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Chinese Bronze
Small articles bronzed by this process possess a peculiar beauty, and lose none of their luster, even when exposed to atmospheric influences and rain. Powder and mix thoroughly 2 parts of crystalized verdigris, 2 parts of cinnabar, 2 of sal-ammoniac, 2 of bills and livers of ducks, and 5 of alum. Moisten the mixture with water or spirit of wine, and rub into a paste; cleanse the article to be bronzed thoroughly, and polish with ashes and vinegar. Then apply the paste with a brush. Heat the article over a coal fire, and wash the coating off. Repeat this operation until the desired brown color is obtained. By adding blue vitriol to the mixture, a chestnut brown color is produced, while an addition of borax gives a yellowish shade.
Gold Bronze for Iron. Dissolve three ounces of finely powdered shellac in 1 1/4 pints of spirit of wine. Filter the varnish through linen and rub a sufficient quantity of Dutch gold with the filtrate to give a lustrous color to it. The iron, previously polished and heated, is brushed over with vinegar and the color applied with a brush. When dry the article may be coated with copal lacquer to which some amber lacquer has been added. Gold Tinge to Silver. A bright gold tinge may be given to silver by steeping it for a suitable length of time in a weak solution of sulphuric acid and water, strongly impregnated with iron rust.
Gold-Yellow Color on Brass. A gold like appearance may be given to brass by the use of a fluid prepared by boiling for about 15 minutes, 4 parts caustic soda, 4 parts milk sugar, and 100 parts of water, after which 4 parts concentrated solution of sulphate of copper is added with constant stirring. The mixture is then cooled to 79 deg. C., and the previously well cleaned articles are for a short time laid into it. When left in it for some time they will first assume a blueish and then a rainbow color. Gray Stain for Brass. Many black and gray pickles possess the defect that they give different colors with different copper alloys, while in the case of certain alloys they refuse to act altogether. For instance, carbonate of copper, dissolved in ammonia, gives to brass a handsome, dark-gray color, while it does not whatever attack various other alloys; therefore it is little suitable for instruments. A dark-gray pickle, which almost indiscriminately stains all copper alloys a handsome gray, resembling in color the costly platinum, is composed by dissolving 50 grams arsenic in 250 grams hydrochloric acid, and adding to the solution 35 grams chloride of antimony and 35 grams finely pulverized hammer scales. The articles to be pickled are rinsed in a weak, warm soda solution, prior to as well as after immersion, to be followed by continued rinsing in water. The recipe is simple, and has been repeatedly tested with uniformly good results.
Green Bronze for Brass. Add to a solution of 8 1/2 drachms of copper in one ounce of strong nitric acid, 10 1/2 fluid ounces of vinegar, 3 1/2 drachms of sal-ammoniac, and 6 3/4 drachms of aqua-ammonia. Put the liquid in a loosely corked bottle, and allow it to stand in a warm place for a few days, when it may be used. After applying it to the articles, dry them by exposure to heat, and when dry, apply a coat of linseed oil varnish, which is also dried by heat.