Blue japan grounds may be formed of bright Prussian blue. The color may be mixed with shellac varnish, and brought to a polishing state by five or six coats of varnish of seed lac. The varnish, however, is apt to give a greenish tinge to the blue, as the varnish has a yellowish tinge, and blue and yellow form a green. Whenever a light blue is desired the purest varnish must always be used.
A good green japan ground may be made by mixing Prussian blue with the chromate of lead, or with tumeric, or orpimen (sulphuret of arsenic), or ochre, only the two should be ground together and dissolved in alcohol and applied as a ground, then coated with four or five coats of shellac varnish. A very bright green is made by laying on a ground of Dutch metal, or leaf of gold, and then coating it over with distilled verdigris dissolved in alcohol, then the varnishes on the top. This is a splendid green, brilliant and glowing.
First clean them thoroughly with soap and water and a little rotten stone; then dry them by wiping and exposure to the fire. Now, get some good copal varnish, mix with it some bronze powder, and apply with a brush to the denuded parts, after which set the tea-tray in an oven at a heat of 212 or 300 degrees, until the varnish is dry. Two coats will make it equal to new.
Orange-colored japan grounds may be made of yellow mixed with vermilion or carmine, just as a bright or rather inferior color is wanted. The yellow should always be in quantity to make a good full color, and the red added in proportion to the depth of the shade. If there is not a good, full body of yellow, the color will look watery, or bare, as it is technically termed.
To paint japan work, the colors to be painted are tempered, generally, in oil, which should have at least one-fourth of its weight of gum sandarach, or mastic, dissolved in it, and it should be well diluted with turpentine, that the colors may be laid on thin and evenly. In some instances it does well to put on water colors or grounds of gold, which a skillful hand can do and manage so as to make the work appear as if it was embossed. These water colors are best prepared by means of isinglass size, mixed with honey, or sugar candy. These colors, when laid on, must receive a number of upper coats of varnish.
Purple japan grounds are made by a mixture of lake and Prussian blue or carmine, or for an inferior color, vermilion. When the ground is laid on and perfectly dried, a fine coat of pure boiled oil is then laid on and perfectly dried, but it is a good method to have a japan not liable to crack. But a better plan is to use this oil in the varnish given, the first coat, after the ground is laid on, and which should contain considerable pure turpentine. In every case where oil is used for any purpose for varnish, it is all the better if turpentine is mixed with it. Turpentine enables oil to mix with either alcohol or water. Alkalies have this property also.