(1) Use transparent colors, like Prussian blue, gamboge, and carmine. These will give the three primary colors, and by their mixture, the other tints. Apply with a brush, and a transparent drying varnish, like dammar varnish. Allow one coat to dry before applying a second. Considerable aid can be derived from stippling, the color being strengthened, where necessary, by applying it with the point of a fine brush. The colors must not be used too thin. (2) Flow the glass plate with albumen, after the manner of photographers, and paint with aniline colors. This process gives great softness and brilliancy to the pictures, but they are apt to fade. (3) Paint with water-colors, and then flow the entire surface with Canada balsam, covering the painted side with a glass plate. (4) Use water-colors, but mix them with turpentine instead of water, and work rapidly.