(lacquer artist). Jurojin and the child are done in metal encrustations of silver, gold, copper, shakudo, and shibuichi. The deer are inlaid mother-of-pearl. The landscape is in gold takamakie and kirigane on a gold ground. 4" x 21/16" x 13/8". 5 cases and lid.
66. INRO. Yamabushi. Signed: Ishiguro Masatsune, with lacquer work by Koma Kyuhaku. The yamabushi is done in encrusted raised metals: shakudo, gold, silver, and copper. The lacquer is gold takamakie on a gold ground. 3" x 23/8" x 11/8". 4 cases and lid.
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Chemical and Physical Properties
Oriental lacquer is not in the Western sense a varnish. A varnish is mainly a gum dissolved in a volatile liquid, such as turpentine, which evaporates, leaving a shiny glaze. Oriental lacquer (except Indian lac, which is the gummy deposit of the insect Coccus lacca) comes from the thick sap of a tree called the urushi (Rhus vernicifera), a species of sumac, which when dried, needs thorough polishing to obtain a highly glazed surface. A knowledge of the chemical breakdown and physical reactions of Japanese lacquer gives us a better understanding of its manufacture and durability. Lacquer consists of 60-85% urushic acid (C14H18O2), a gum (3-6.5%) similar to gum arabic, an albuminoid (1.7-3.5%), a trace of a volatile acid and water (10-34%). The best lacquer is the most transparent, most resistant to solvents and water and that which does not tend to dry up, crumble, or warp with age. The most important process in lacquer manufacture is the slow drying and hardening of lacquer. Lacquer dries best between 68° and 80° F and in the presence of moisture. Chemically the hardening process consists of the albumin acting on the urushic acid, probably as a ferment, with the water acting as a solvent on the albumin so that it can combine with the urushic acid. This probably explains why moisture is actually necessary for liquid lacquer to harden. The gum plays no part in the hardening process but keeps the various components in an emulsion. This hardening of the lacquer is accompanied by the absorption of one atom of hydrogen by one molecule of urushic acid.
C14H18O2 + O --> C14H18O3 (oxyurushic acid). Except for concentrated nitric acid, the oxyurushic acid is insoluble in every solvent, even boiling sulphuric acid, and is stable with temperatures below 200°. The gum and albumin, however, are attacked by concentrated acids and alkalis but not by the solvents (alcohol, ether, benzene, ammonia, etc.). Water may cause the gum to swell, and when drying occurs there may occur crumbling and warping, especially in the cheaper lacquer, in which there is more gum. Old lacquer (50-100 years old), through gradual chemical changes in the gum, is therefore not affected by water. In general it is apparent from the preceding chemical discussion, and confirmed by practical application, that the best lacquer has the highest percentage of urushic acid (80-85%), a corresponding low percentage of water (10%), and relatively little gum and albumin. The durability of good, old lacquer is dramatically illustrated in the sinking in 1874 of the French steamer Nil, which was carrying back Japanese art objects from the Vienna exposition. Eighteen months later the old lacquer ware was recovered from the ocean and found to be in perfect condition. Chinese lacquer is somewhat inferior to Japanese lacquer because of the lower percentage (55%) of urushic acid and probably also because of the fact that it is softened by mixing with a vegetable oil. Also, Chinese flat lacquer is not made with as many layers of lacquer as are works done by the Japanese artisan.
Preparation of Various Lacquers
As noted, Japanese lacquer comes from the thick sap of a tree called the urushi. Originally these trees were planted by order of the government. In ten years a tree grows to about ten feet high and will yield two to three ounces of sap. The trees are tapped between June and October. The spring sap is considered too watery, the midsummer sap being the best in quality. Special tools and methods are used for obtaining the sap. In general, when the tree is two to ten years old it is incised at specific levels, averaging about 25 cuts. Cuts are also made into the branches. The exuding lacquer is scraped into bamboo pots (go). The crude thick creamy lacquer called urushi is then filtered of impurities through a cloth. When filtered it is called ki-urushi. Lacquer taken from different parts of the tree and that taken from older trees have different characteristics. Each type of lacquer so obtained is kept separately, and subsequently each is used for specific purposes. Thus the sap taken from the trunk of very old trees (100-200 years old) produces the best transparent lacquer and is called suki-urushi. Similarly, the branch lacquer, or seskime-urushi, is highly desired, since when dry it becomes extremely hard. However, it dries more slowly than trunk lacquer.
The excess water in the lacquer is evaporated, paradoxically, by adding small amounts of water. Lacquer will not dry perfectly in the open air, but only in a damp enclosed atmosphere between 68° and 80° F. In drying lacquer the Japanese enclose the object in a damp cupboard, damp press (muro), or damp cellar. The press is kept humid by repeated sponging down with water. It may require two to three days for one layer of lacquer to dry and in some cases up to one month for thorough drying. In general, a layer of lacquer is applied to the prepared object, which is dried in the damp press, and then polished. This process is repeated numerous times, employing different types of lacquer, different periods of drying, and different techniques of polishing. This is all done preparatory to the actual process of ornamentation. The following is a partial list of the different types of lacquer, their production, and their uses:
1) middle-coating lacquer (naka-nuri-urushi). Used for middle coats and prepared by thoroughly evaporating good ki-urushi.
2) black lacquer (ro-urushi). Prepared from crude or branch lacquer by the addition of a black solution (haguro) made by boiling iron filings in strong rice vinegar.
3) inside-line lacquer (ke-uchi-urushi). Made from shita-maki-urushi (undercoat lacquer), which in turn is made from seshime-urushi and iron oxide. It is kept for months in order to thicken, thereby allowing fine lines to be drawn on raised work. The consistency prevents the lines from spreading and also gives the desired relief.
4) shading lacquer (kuma-urushi). Prepared from jo-hana-urushi and lampblack, which lacquer in turn is made by adding small amounts of oil and finishing lacquer. It is used for shading with very delicate lines on flat and raised ware.
5) raising lacquer (taka-maki-urushi). Made by boiling ro-urushi, lampblack, and camphor. This lacquer is applied thickly. The camphor renders the lacquer soft, and it dries slowly and evenly. In this way the top layer does not dry first, and subsequent cracking of the top layer does not occur.
6) ro-se-urushi. Made from a mixture of seshime and ro-urushi. It is used as a lacquer base to imbed metallic powders or flakes of gold, silver, or tin.
7) pear-basis lacquer (nashiji-urushi). Transparent lacquer obtained from old trees. It is put over the metallic powderings.
8) sabi. Composed of 2 parts burnt clay and 11/2 parts seshime-urushi. It is used to build up the high relief of takamakie.
9) jinoko. Composed of 1 part burnt clay and 2 parts seshime-urushi.
10) suki-urushi. The best crude lacquer, used for colored lacquer.
Lacquer is colored by the addition of various pigments, but no vegetable colors are used, since they are destroyed by the lacquer and will fade. Therefore colors, such as white and purple, are not seen in early lacquer work. In general, colors are used either pulverized as powders or mixed with metallic powders, the design being made by dusting the appropriate powders on the sticky lacquer. In other cases the lacquer itself is colored by mixing it with colored pigments. The lacquer used
