The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Coloring Finishing And Painting Wood
Finishes made from them have a brilliant and permanent luster which is unchangeable with weather conditions. The oriental lacquers are also said to be impervious to varnish-removers and other solvents.
An interesting peculiarity of Japanese lacquer made from the Rhus tree is that it hardens properly only in a moist atmosphere. If exposed to heat and sunlight, it remains in a tacky condition instead of drying properly. Oxidation takes place during the drying of a film, and sometimes as much as 53/4 per cent of weight may be added during the drying process at ordinary temperature.
The black lacquer or "thitsi" of Burma is made in a manner somewhat similar to that used in compounding the famous Japanese lacquer; but in this case the gumlike material comes from a different tree, the Melanorrhea usitata. The black lacquer of Burma is slower in drying than the Japanese lacquer.
The lacquer commonly used in Europe and the United States before the World War was simply a spirit-varnish. It was often largely shellac, which takes its name from lac or "lakh." In the dictionaries or text-books written a few years ago, lacquer is said to be a shellac or spirit-varnish. These so-called lacquers were made in large quantities in both clear and colored solutions and were used sometimes on wood, but much more often on metals, such as brass especially, to prevent tarnishing and to give a soft pleasing luster.
Other spirit-soluble gums, such as sandarac and elemi, were often added to the mixture of shellac and alcohol in compounding the lacquer. Spirit-soluble vegetable dyes were formerly used in these spirit-varnish lacquers, but coal-tar dyes gradually replaced them as dyestuffs in colored lacquers. Lacquers of this type were very thin, and had little body; consequently a very large number of applications was necessary. These early lacquers were quite satisfactory and durable, and could be made to adhere more firmly to nietalwork when baked on at temperatures under 115° C, which is the melting-point of shellac. Lower temperatures than the melting-point will soften and fuse the shellac-gum very firmly to the metal.
The oriental lacquers as well as the spirit-varnish or shellac lacquers, just described, are really varnishes, and not lacquers, in the sense that the word is now used in the United States. The metal trades for a number of years have been trying a new type of lacquer for a very tough, hard finish. This finishing-material was manufactured in the form of clear lacquer, and also in pigmented compounds, sometimes called lacquer-enamels. It was necessaiy to make this material very thin in order to apply it at all, which resulted in very thin films and many coats. It was not satisfactory in the early forms for finishing wood, be cause it did not adhere properly and soon peeled or scaled off.
