Substitute Paint Varnish.

The Scientific American 46, 4.8.1849

Recipe for a composition to economise paint: - To one pound of gum shellac add 4 ounces of borax, and two quarts of water. - Boil till dissolved. These proportions may be varied according to the quality of the materials used. After the paint is prepared fr use add nearly an equal quantity of the above and stir until it unites. The paint will then be thicker than before, and must be reduced with oil or spirits of turpentine. The paint will now cover twice the surface as at first.