Purified linseed oil is boiled for six or eight hours, and to every 100 pounds of boiled oil there are added five pounds of powdered peroxide of manganese, which may be kept in a bag like litharge. The liquid is boiled and stirred for five or six hours more and then cooled and filtered. This drying oil is employed in the proportion of from five to ten per cent of the weight of zinc white, and it should be added during the grinding of the pigment in oil, the admixture then being more thorough.

Drying Oils

Fifteen parts of lime made into paste with water are added to 100 parts of oil oxidized by peroxide of manganese. The whole is boiled or heated by steam until the water has evaporated; the oil then forms with lime a thick product which is a drier. It may be ground with the ordinary oil of turpentine, or with that of Venice, but the dryer is less powerful than when it has been mixed with oxidized linseed oil. Three to five per cent of this drier are sufficient for a rapid desiccation.

Other driers may be made by combining lime with resins and essence of turpentine in the proportions indicated for fixed oils.