About Metallic Pigments

The demand for various metallic paints which are made from powders of bronze, aluminum, zinc, tin, copper, and gold, together with a proper varnish medium or some bronzing liquid as a vehicle has grown greatly during recent years. Metallic paints are highly decorative under proper conditions and are valued because of their anticorrosive qualities when they are used to cover metals such as radiators for steam and hot water heating. Metallic paints are good conductors of heat.

The alloy for making an imitation gold bronze is made from copper and zinc. The reddish gold bronzes contain from 1 to 5.6 per cent of zinc, while the yellow or light gold bronzes may include from about 15 to 19 per cent of zinc in their composition. Bronze powder is made from thin sheets of the metal, which are ground into very fine particles. Various color effects can be obtained in the metallic powders by heat treatments, as by heating in a paraffin bath.

New hues are produced by mixing certain coal tar dyestuffs in the paints to secure the desired color. A painter can change the colors of bronzes by the addition of colors ground in Japan. Colors ground in oil do not dry quickly nor mix well in lacquer. White bronze is made of the metal, aluminum, by grinding it into fine powder. About six pounds of bronzing powder to each gallon of bronzing liquid are generally used in gold bronze or common bronze powders.

Much less aluminum powder can be used because it is very light and more bulky. It is usual to mix only about 11/2 to 2 pounds of the dry aluminum powder to the gallon of bronzing liquid. Sometimes bronze powders are measured instead of weighed for mixing. A tablespoonful of bronze powder to each pint of lacquer makes a bronze paint that covers satisfactorily. The bronzing liquid may be a very heavy bodied boiled linseed oil. Rapid drying bronzing liquids are sometimes made from mixtures of heat treated linseed oil and tung oil, together with Japan driers and benzine as a thinner.

New hues are produced by mixing coal tar dyestuffs in the paints to secure the desired color. A painter can change the colors of bronzes by the addition of colors ground in Japan. Colors ground in oil do not dry quickly or mix well in lacquer.