Pastels - Supports and Grounds for Pastel

Special pastel papers exist which are usually made by coating their surface with an adhesive over which pumice or some other material is sprinkled to provide additional tooth. Such grounds may be made by painting a mounted paper or cardboard with casein solution (made according to recipe A - See Casein--4 onces by weight of casein to 1 quart water). While still wet, the surface is sprinkled evenly with fine pumice powder. When the casein has dried well, the excess pumice is dusted off.

Starch solution is sometimes recommended for this sort of ground in place of the casein. In this case 2 and 1/4 ounces (av.) of pure rice starch are dissolved in 1 pint of hot water. This is stirred till cool, making a smooth paste which is brushed thinly and evenly over the support and then sprinkled with pumice powder. However, a casein ground is less vulnerable to mold, being less hygroscopic.

When tinted papers or cardboards are used, with the intention of allowing their tone to play a part in the final color scheme of the picture, it is important that the color of the paper be lightfast and not some cheap commercial ink that will fade in a short time. Artists can use watercolor, qouache, or various tempera paints to tint their papers or cardboards before working on them with pastel. [pp. 210-211]