Binders and Diluents - Driers

Lead Drier, Manganese Drier, and Cobalt Linoleate Drier are the types usually found on the market today. Of these, the cobalt drier is considered by most authorities to be the least harmful. Siccatif de Courtrai contains lead and manganese driers, plus oils and thinner. Siccatif de Haarlem is said to contain boiled oil and varnish.

Driers should not be poured at random into the palette cup to be mixed in indefinite amounts with the painting medium. The correct small percentage of drier [usually 2 or 3 drops to a spoonful of paint] will speed the drying as efficiently as a much larger amount. An excess of drier may cause the paint to become gummy, and it insures later darkening and cracking. By systematically decreasing the amount of drier, the artist can soon ascertain the smallest amount of siccative that will cause the color to dry at an acceptable rate.

In many cases a fast drying painting medium, made up of such ingredients as dammar varnish, sun-thickened linseed oil, and turpentine, used with a palette of fast-drying pigments, can develop paintings that will dry with sufficient speed to please most artists. Such combinations are safer to use than the addition of driers.

It may be noted that pigments that contain lead, manganese, or cobalt--the three metals used in making siccatives--are all very rapid driers in linseed oil. [p. 62-62]