The following formulas are in use:
Black.—One part of turpentine is warmed for 20 minutes beyond the fusing point; then poured into 3 parts of lac; at the same time pheu deu (copperas) is added. The mixture is stirred for at least a day, sometimes more, by means of a large paddle.
Maroon.—This is prepared by a process similar to the preceding, replacing half of the copperas by an equal quantity of China vermilion.
Red.—The lac, previously stirred for 6 hours, is mixed with hot oil of trau, and the whole is stirred for a day, after which vermilion is added. The latter should be of good quality, so as to have it brilliant and unchangeable.
The operation of lacquering is then ended, but there are parts to be gilded. These are again covered with a mixture of lac and oil of trau. When this layer is dry the metallic leaves are applied, which are themselves protected by a coating, composed also of lac and oil of trau. All these lac and oil of trau mixtures are carefully filtered, which the natives effect by pressing the liquid on a double filtering surface formed of wadding and of a tissue on which it rests. It can only be applied after several months when the metallic leaf is of gold. In the case of silver or tin the protecting coat can be laid on in a few days. It favorably modifies the white tints of these two metals by communicating a golden color. The hue, at first reddish, gradually improves and acquires its full brilliancy in a few months.
Little information is procurable concerning the processes employed by the Chinese. The wood to be lacquered should be absolutely dry. It receives successive applications, of which the number is not less than 33 for perfect work. When the lac coating attains the thickness of 1/4 of an inch it is ready for the engravers. The Chinese, like the inhabitants of Tonkin, make use of oil of trau to mix with the lac, or oil of aleurites, and the greatest care is exercised in the drying of the different layers. The operation is conducted in dim-lighted rooms specially fitted up for the purpose; the moisture is maintained to a suitable extent by systematically watering the earth which covers the walls of this “cold stove.”
Lacquer For Aluminum.
Lacquer For Brass.—
| Annatto | 1/4 ounce |
| Saffron | 1/4 ounce |
| Turmeric | 1 ounce |
| Seed lac in coarse powder | 3 ounces |
| Alcohol | 1 pint |
Digest the annatto, saffron, and turmeric in the alcohol for several days, then strain into a bottle containing the seed lac; cork and shake until dissolved.