First clean the medal, then apply on its surface a thin paste made of water with equal parts of peroxide of iron and plumbago, with a small proportion of clay. Heat the whole, and when the object has cooled, brush vigorously for a long time with a medium stiff brush, which is frequently rubbed upon a yellow waxen black and afterwards upon the mixture of peroxide of iron and plumbago.
3 parts Diluted Acetic Acid, 7 parts Sal-ammoniac, 5 parts Crystallized Acetate of Copper, 85 parts Distilled Water, and then rub the article with a solution consisting of 4 parts Oil of Turpentine, 1 part Wax.
A liquid for giving a brown tinge to copper is made by the addition to acetic acid of 11 drachms of spirit of sal-ammoniac; blue litmus paper, when dipped in same, becomes red. Next add 5 1/2 drachms of sal-ammoniac and enough water to make 2 pints. This fluid is to be used, wetting the copper surface again and again, and rubbing after each application until the brown tint desired is obtained.
A good brown on metal may be had by dissolving 68 grams of carbonate of ammonia in 1,000 grams of hot water, to which 56 grams of citrate of copper oxide should be added while stirring, and then 100 grams of verdigris and 25 grams of alum that has been previously dissolved in 200 grams of water should be added, and finally 10 grams of oxalic acid. Brush twice with tartar water.
Brunswick black is made as follows:
(1) Foreign asphaltum, 45 pounds; drying oil, 6 gallons; litharge, 6 pounds. Boil and thin with 25 gallons of oil or turpentine. Used for iron work, etc.
(2) Black pitch and gas tar asphaltum, of each 25 pounds; boil gently for five hours; then add linseed oil, 8 gallons; litharge and red lead, of each, 10 pounds; boil slowly, and thin with oil of turpentine, 20 gallons. Inferior to the other, but cheaper.
The first step in burnishing silver is to clean off any dirt which the surfaces of the silver articles may have contracted during the process of their manufacture. To do this take pumice-stone powder and with a brush saturated in strong soapsuds rub the various parts of the article, even those which are to remain a dull color, which, nevertheless, are thus given a beautiful white appearance. After wiping with an old linen rag go ahead with the burnishing.
To restore burnt cast-steel use a mixture consisting of:
1 part Dragons' Blood, 8 parts Salt-petre, 4 parts Colophony.
The article is to be heated to a dark-red heat and dusted with this compound. After the absorption of the powder is complete the article is to be thoroughly worked upon an anvil.
(2) Another compound for this purpose consists of:
4 parts Salt-petre, 1/2 part Gum Arabic, 1/2 part Aloes, 1/4 part Resin,
8 parts Red Chromate of Potassium, with which the steel, when red-hot, is dusted.
(3) Another method consists in the repeated immersion of the red-hot burnt steel in a compound of:
2 parts Boiled Linseed Oil,
3 parts Colophony.