The oil grounds are made by mixing tobacco-pipe clay and Spanish white with water, to the consistency of a thick paste; then free it from sand and other impurities; mix it afterwards with drying oil, and any tint you may choose, by the addition of colour, and spread it over the cloth with a trowel or palette- knife, and it will not go through the cloth; the closer the texture of the cloth, the better for the purpose. Panels of either oak or mahogany are prepared in the same way; the inequalities are rubbed down with pumice-stone, as directed for the absorbant grounds; or, upon a well planed panel, lay on common white lead, with a palette-knife or trowel; when dry, rub it over, till smooth, with pumice-stone and linseed oil., ,