Copper Work: A Text Book for Teachers and Students in the Manual Arts

by Augustus F. Rose

A piece of silver solder, a slate slab such as is ordinarily used for grinding ink, powdered or lump borax, and a soft hair brush of some sort are all that is necessary for the process of soldering in addition to what we already have.

The pieces of metal that are to be soldered must be absolutely free from all foreign matter. To insure this the joint is scraped bright with some sharpe-edged tool. Care must be taken to keep the fingers away from the joint as any moisture or greasy substance will prevent the solder from running. The best results are obtained only by being extremely careful as to cleanliness throughout the process. Being sure that the slab is perfectly clean, a little water is put in it and the lump of borax is ground around until the water becomes like thin cream. If powdered borax is used a block of wood will answer as a pestle to grind the borax to the right consistency.

The solder may be obtained any gauge, but about 20 answers for most purposes. After cutting the solder into pieces about 1/16 of an inch long and about the same width, drop them into the borax that has been ground to give them a coating of borax and to remove any grease that may have adhered to them. Coat the surfaces that are to be soldered with the borax being careful to get no more borax about than is necessary. Put the parts together and bind them with No. 24 iron wire, not too tightly. The pieces of solder are then lifted with the brush used for the borax or with a pair of tweezers and placed next to the edge that is to be soldered, about one inch apart. The object is then placed on the annealing tray, which answers for soldering as well, and with the blow-pipe it is heated, very slowly at first until the water has evaporated and the borax crystallized and dissolved, the flame may then be applied more directly and the object brought to a soldering heat. If the heat is applied too quickly, it will throw off the solder; and if heated hotter than necessary it is liable to melt or burn the parts being soldered, so the process demands the closest attention from the start.

The object is then pickled, washed in clear water and dried in the sawdust.

If the above directions are carefully followed good results may be expected.

REPOUSSE OR EMBOSSING.

Repousse or embossing involves practically the same principle as modeling in clay or wax, the only difference being that metal is used as the material and that different tools are employed. In this, as in clay or wax work, it is desirable to bring certain parts of a design into relief; to do this with metal the work must be placed on a substance which will give some resistance and yet allow each blow of the hammer or tool to make an impression. The substance commonly used for this purpose has the following composition, in the proportions given:

Black pitch 1 lb.
Tallow 3 teaspoonfuls.
Plaster of Paris 1/2 cup.

The pitch is put in some kind of dish (agate is good), placed over a gas plate, and melted. The tallow is then added and the plaster sprinkled and stirred in, the whole being well mixed. It is then poured into the pitch pot, or whatever it is to be used in. When used in hot weather more plaster must be used. A pot, hemispherical in shape, [Figure 21], made of cast iron about ½ inch thick is generally used. This, when placed on a chaser's pad or ring, Figure 21, may be turned at any angle, and is found to be a great convenience. An ordinary 7" × 12" baking pan of iron serves the purpose, or a box may be made of wood, but of course this is not so durable.

After allowing the composition to cool partly, yet while soft enough to stick, the piece of work that is to be embossed is placed on it, the right side next to the pitch. It is then allowed to cool still more; when quite hard or when it is difficult to make an impression on it with the thumb nail, it is ready to work on. The design is next drawn or transferred to the metal by the use of carbon paper and then scratched on with a scratch awl to make the drawing more permanent, as in going over the piece of work the pencil or carbon lines are easily erased.