2. Tincture of sesqui-chloride of iron, one-half ounce; corrosive sublimate, one drachm; sulphate of copper, one-half drachm; nitric acid, one drachm to one and a half drachms; alcohol, six drachms; water, eight ounces. Dissolve the corrosive sublimate in the alcohol, then add the solution to the other ingredients and let the whole stand for a month or six weeks, when it will be ready for use.
3. Sweet spirits of nitre, one ounce; tincture of steel, one-half ounce; blue vitriol, one-quarter ounce; nitric acid, six drops; corrosive sublimate, fourteen grains; water, one pint. When the barrels are dark enough, drop a few drops of muriatic acid in water and wash the barrel slightly to brighten the twists.
4. Muriatic tincture of steel, one ounce; alcohol, one ounce; muriate of mercury, one-quarter ounce; strong nitric acid, one-quarter ounce; blue vitriol, one-eighth ounce; water, one quart. Thoroughly mix the ingredients. Let them stand about thirty days before using. Wet the barrels with the mixture, applied with a sponge, about once every two hours. Scratch off with wire card every morning until the barrels are dark enough.
To Blue Gun Barrels.—A very pretty bluish color may be imparted to gun barrels by dressing them off to brightness with fine emery paper, and then rubbing them over quickly with nitric acid. When the desired color has appeared, wash them off with clean water, rub dry with a soft cloth, and then rub with linseed oil to prevent any further action of the acid.
Brown Tint for Iron or Steel.—Dissolve, in four parts water, two parts of crystalized chloride of iron; two parts of chloride of antimony; and one part of gallic acid, and apply the solution with a sponge or cloth to the barrel, letting it dry in a warm place. Repeat the process according to the depth of color desired. Wash with warm water, and dry; then rub over with boiled linseed oil. The metal receives a brown tint and resists moisture. The chloride of antimony should be as little acid as possible.
Transparent Blue for Iron or Steel.—Put together Demar varnish, one quart; fine ground Prussian blue, one-quarter ounce. Polish the metal to brightness, and put on thinly with a varnish brush. A beautiful transparent blue color, but one that will not stand rough usage.
Varnish for Browned Barrels.—1. Dissolve ten parts clear grains of mastic, five parts camphor, fifteen grains sandarac, and five parts elemi, in a sufficient quantity of alcohol, and apply the varnish without heat. The articles treated with this varnish will not only be preserved from rust, but their metallic lustre will not be in the least dimmed by exposure to dampness.
2. Another varnish may be made by using gum shellac, one ounce; gum sandarac, one ounce; Venice turpentine, one drachm; and ninety-eight per cent. alcohol, one gallon.
3. Another formula consists of shellac, one ounce; dragon’s blood, one-quarter of an ounce; alcohol, one quart. A little less dragon’s blood may be used if the color be too great.
Finish for Browned Barrels.—There are many ways of finishing barrels after browning. Some gunsmiths warm the barrels and rub them while quite warm with a flannel cloth and finish with a little bees-wax and turpentine. Some polish with a steel burnisher or rub with white wax; others use a wash of thin shellac varnish laid on carefully and evenly with a camel’s hair brush. Some finish off with a solution of two ounces of shellac and three drachms of dragon’s blood dissolved in two quarts of good alcohol.