A good black ground for japanning is prepared by grinding fine ivory black with a sufficient quantity of alcoholic shellac varnish on a stone slab with a muller until perfectly smooth black varnish is obtained. If other colors are required the varnish is mixed and ground with the proper quantity of suitable pigments in a similar manner. The following are good common black grounds:
(1) Asphaltum, 1 pound; balsam of copaiba, 1 pound; oil of turpentine, q. s. The asphaltum is melted over a fire, and the balsam, previously heated, is mixed with it. The mixture is then removed from the fire and mixed with turpentine.
(2) Moisten good lampblack with oil of turpentine, and grind it very fine with a muller on a stone plate. Then add a sufficient quantity of ordinary copal varnish and rub well together.
(3) Asphaltum, 3 ounces; boiled oil, 4 quarts; burnt amber, 8 ounces; oil of turpentine, q. s. Melt the asphaltum, stir in the oil, previously heated, then the umber, and when cooling thin down with the oil of turpentine.
An extra black is prepared from: Amber, 12 oz.; asphaltum, purified, 2 oz.; boiled oil, 1/2 pint; resin, 2 oz.; oil of turpentine, 16 oz. Fuse the gum and resin and asphaltum, and the hot oil, stir well together, and when cooling add the turpentine. A white ground is prepared from copal varnish and zinc white or starch. From one to six or more coats of varnish are applied to the work of japanning, each coat being hardened in the oven before the next is put on. The last coat in colored work is usually clear varnish.