3781. Green Bronzes for Figures and Busts

3781. Green Bronzes for Figures and Busts. Green bronzes require a little more time than those already described. They depend upon the formation of an acetate, carbonate, or other green salt of copper upon the surface of the medal. Steeping for some days in a strong solution of common salt will give a partial bronzing which is very beautiful, and, it washed in water and allowed to dry slowly, is very permanent. Sal ammoniac may be substituted for common salt. Even a strong solution of sugar, alone, or with a little acetic or oxalic acid, will produce a green bronze ; so also will exposure to the fumes of dilute acetic acid, to weak fumes of hydrochloric acid, and to several other vapors. A dilute solution of ammonia allowed to dry upon the copper surface will leave a green tint, but not very permanent.

3782. Bronzing with Bleaching Powder

3782. Bronzing with Bleaching Powder. Electrotypes may be bronzed green, having the appearance of ancient bronze, by a very simple process. Take a small portion of bleaching powder (chloride of lime), place it in the bottom of a dry vessel, and suspend the medal over it, and cover the vessel; in a short time the medal will acquire a green coating, the depth of which may be regulated by the quantity of bleaching powder used, or the time that the medal is suspended in its fumes; of course, any sort of vessel, or any means by which the electrotype may be exposed to the fumes of the powder, will answer the purpose; a few grains of the powder is all that is required. According as the medal is clean or tarnished, dry or wet, when suspended, different tints, with different degrees of adhesion, will be obtained.

3783. Fine Green Bronze

3783. Fine Green Bronze. Dissolve 2 ounces verdigris and 1 ounce sal-ammoniac in 1 pint vinegar, and dilute the mixture with water until it tastes but slightly metallic, when it must be boiled for a few minutes, and filtered for use. Copper medals, etc., previously thoroughly cleaned from grease and dirt, are to bo steeped in the liquor at the boiling point, until the desired effect is produced. Care must be taken not to keep them in the solution too long. When taken out, they should bo carefully washed in hot water, and well dried. Gives an antique appearance.

3784. To Bronze Brass Orange, Greenish Grey and Violet Tint

3784. To Bronze Brass Orange, Greenish Grey and Violet Tint. An orange tint, inclining to gold, is produced by first polishing the brass, and then plunging it for a few seconds into a neutral solution of crystallized acetate of copper, care being taken that the solution is completely destitute of all free acid, and possesses a warm temperature. Dipped into a bath of copper, the resulting tint is a greyish green, while a beautiful violet is obtained by immersing it for a single instant in a solution of chloride of antimony, and rubbing it with a stick covered with cotton. The temperature of the brass at the time the operation is in progress has a great influence upon the beauty and delicacy of the tint; in the last instance it should be heated to a degree so as just to bo tolerable to the touch.