Hard Solders.—1. A hard solder that is yellow and easily fusible is made of copper, 4½ parts, and zinc, 5½ parts.
2. To hard solder iron use good tough brass or sheet copper, with borax as a flux.
3. Pure copper, cut in thin strips, with borax as a flux, is excellent for brazing iron or steel.
Alloy for Adhering to Iron or Steel.—Melt together, tin 3 parts, zinc 7½ parts, and copper 39½ parts. Clean the iron or steel, file to brightness and cast the alloy upon it. The iron or steel should be heated up to about the melting temperature of the alloy. This alloy will adhere firmly to the other metal, and as its rate of expansion is about the same as the iron or steel, under all circumstances, it will never come loose. It finishes up nicely and presents a very neat, light yellow appearance. Some gunsmiths use it for brazing purposes on account of its adhesive properties and its ease of fusion. It does not make so strong a joint as brass or copper, and therefore would not give so “honest” a job.
Gun Oil.—A good quality of sperm oil is undoubtedly the best oil to apply to gun work, especially the locks. Any fine animal oil may be used as a substitute. The oil from the fat of the woodchuck or ground-hog is admired by many. Fine quality of sewing-machine oil is very good. It must not be thinned or “cut” with kerosene or benzine, as this reduces its wearing quality. It must not thicken with exposure to the cold.
Vegetable oils are unfit for the locks of guns. Castor oil will gum up and become filthy in the extreme. Olive oil or “sweet oil” has very often been agitated, with common salt, nitric ether, sulphuric acid or hydrochloric acid to keep it from becoming rancid. Application of such oil, in addition to its bad lubricating quality, will rust and spoil work where applied.
If desired to clarify oil, put in a bottle, say a quart of oil, and add about half a pound of fine lead shavings. In a short time the impurities will collect on the lead, when the clarified portion may be poured off. Let the bottle stand in the sun for two or three weeks during the process, and then filter through fine white blotting-paper. If some portion be found to congeal by cold, separate the clear portion from the other, reserving the uncongealed for use during exposure of the gun to cold weather.
Gunsmith’s Glue.—Dissolve four ounces of good glue in sixteen ounces of strong acetic acid by exposure to gentle heat. This is not exactly a liquid glue preparation—it is only semi-liquid. It may be kept for any length of time desired, and, when wanted for use, a slight warming up is all the preparation necessary. The gunsmith finds it not only very convenient, in case he should have occasion to use glue about his woodwork, but also very good.