Another standard method of finishing copper is to give it any of the many various green finishes that are known on the market and in the trade as "Antique Patina," "Verde antique," "Pompei Green," "Green Patina," etc. The same finish is often given different names by different manufacturers. Some of the most reliable of these finishes are as follows:
No. 1. Copper nitrate, 16 grains; ammonium chloride, 16 grains; calcium chloride, 16 grains; water, 1 ounce. Brush the solution on the article with a stiff brush and allow it to dry; if necessary apply a second time, then relieve with emery cloth, and lacquer or wax.
No. 2. To obtain a green color on either copper or brass: ammonia muriate, 1 ounce; ammonia carbonate, 3 ounces; water. 24 ounces.
No. 3. A popular so-called verde antique finish on copper and brass is produced by the use of this formula: common salt, 4 ounces; chloride of iron crystals, 1 ounce; verdigris, 3 ounces; sal ammoniac, 5 ounces; cream of tartar, 2 ounces; water, 1 pint. Immerse the work in the solution and allow to dry.
2Aqua regia is equal parts of nitric acid and muriatic acid mixed together; it is the only solution that will dissolve gold.
No. 4. For a yellowish green on copper use the following: copper nitrate, 1 ounce; sal ammoniac, 1 ounce; chloride of calcium, 1 ounce; water, 2 quarts. Apply with a stiff brush and allow to dry.
No. 5. For an olive green color on copper and brass: one part of perchloride of iron and two parts of water mixed together will give copper or brass a pale or deep olive green, according to the time that the work is left in the solution. The work must be immersed and then allowed to dry.
No. 6. Another green solution is composed of nitrate of iron, 2 ounces; hyposulphite of soda; water, 1 pint.
No. 7. A good antique green can be obtained by using the following solution: 1 part sal ammoniac, 3 parts cream of tartar, 3 parts common salt, 12 parts boiling water, 8 parts cupric nitrate. Apply with a brush and allow to dry.
No. 8. If copper or brass is dipped in acetic acid and then exposed to the fumes of ammonia for a few hours the metal will acquire a mixture of black, blue, and green colors.
No. 9. Olive green on copper: 2 parts water, 1 part permu riate of iron.
No. 10. A recipe for green coloring that is good on copper, brass, or bronze is as follows: sal ammoniac, 5 parts; acetic acid, 10 parts; common salt, 1 part; cream of tartar, 1 part; acetate of copper, 1 part; water, 1 part. Mix thoroly and apply with stiff brush.