Art Metalwork Chapter 6 Cont.

APPLYING SILVER SOLUTIONS

There are also some interesting methods of, applying a thin coat of silver to copper articles, and while this method is not recommended for very  extensive use, still some very good effects can be produced by applying the silvering solution to the copper where a design has been etched or chased and then rubbing with an old smooth piece of emery cloth, allowing the silver to remain in the background. The copper must, of course, be perfectly clean.

No. 1. With a little water make a paste of nitrate of silver 80 grains,  common salt 40 grains, cream of tartar 7 drachms, and rub on to the copper.
No. 2. Another silvering paste is made of chloride of silver, 4 ounces; cream of tartar, 75 ounces; common salt, 10 ounces, and water sufficient to form a paste. Keep this paste away from the light, and apply by rubbing on the copper with a piece of cloth.
No. 3. A good silvering fluid is composed of distilled water, 5 ounces; chloride of silver, 7 ounces; potassium oxalate, 10 ounces; common salt, 30 ounces; chloride of ammonia, 4 ounces. Mix together and apply by rubbing on the metal with a piece of soft cloth
No. 4. Another simple method of silvering copper and brass is to put one ounce of aquafortis and one ounce of silver scraps in a crockery dish and set it in a warm place until the silver is entirely dissolved. Then mix with it enough cream of tartar to make a thin paste. This paste will silver copper or brass when rubbed on with a soft cloth.

GILDING AND BRONZING

Copper and brass can be gilded by using the following solution : distilled water, 1 quart; 6 pennyweights of gold converted into chloride, potassium bicarbonate, 16 ounces. To prepare this solution for use, convert the gold into chloride by dissolving it in aqua regia. Then dissolve in the distilled water, add the potassium bicarbonate, and allow the solution to simmer over a fire for about one hour. The articles to be gilded are immersed in the warm fluid for a few seconds until the desired color is obtained.
Another good recipe for gilding by boiling is cyanide of potassium, 8 ounces ; chloride of gold, 3 pints ; sal soda, 8 ounces ; water, 1 gallon.
To get a bronze effect on copper, dissolve 3 ounces of nitrate of iron and 1 ounce of sulphocyanide of potassium in 2 quarts of water, and immerse the articles.

ANTIQUE FINISHES

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," .. Pompel 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; cafe]-am 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 ;

(Aqua regia is equal parts of nitric acid and muratic acid mixed together; it is the only solution that will dissolve gold.)

sal ammoniac, 5 ounces; cream of tartar, 2 ounces, water, 1 pint. Immerse the work in the solution and allow to dry.
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 permuriate 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.

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