AGELESS VEGETABLE LACQUER

Wanganui Chronicle, Volume 80, Issue 67, 21 March 1938, Page 3

AGELESS VEGETABLE LACQUER

May be Used for Many Purposes

fjHERE are two natural products bearing the name of lacquer which both originate in the Far East; gum-lacquer and the latex of certain trees, writes Georges Brooks in La Nature, Pans. Gum-lacquer is the resinous animal secretion of an insect, the lac-insect. It is composed of resin mixed with colouring matter and wax. After various stages of treatment it enters into the fabrication of ajcohol varnishes and into the composition of phonograph discs. The real lacquers are of vegetable origin. They are produced from latex obtained in the trunks of various trees such as the Rhus vernicifera in China and Japan, the Rhus succedanea ia Tonkin and the Melanorrhoea laccifera in Cochin China and Cambodia. In a . raw state the latex is of creamy aspect and consistency. It possesses a slightly butyric odour at first, becoming strongly acetic at the end of four or five years. The latex of the Melanorrhoea has a disagreeable odour reminiscent of rancid oil. Contained in earthenware jars and kept in a dark, cool place, it will retain its essential property for several years. The cultivation of lac trees is on the decrease in Japan and China, but in Tonkin it is becoming more important every day. Tonkin is the only place in the world which exports the precious latex to neighbouring countries and to Europe. When making lacquer, the latex is first strained to free it from all impurities. Afterwards it is churned to separate the -water. On the care with which this is done, the quality of the lacquer depends. It is strained once tnore and then it is ready for use by itself or mixed with oil of Abrasin, siccatives, and suitably chosen mineral pigments. The lacquer thus prepared is used to varnish those marvels of Asiatic art which are the wonder of the world. In drying the lacquer forms a very adherent film which can resist all th? usual solvents, including acids and concentrated alkalines. The Orientals have used it for more than 2000 years. Resistant to chemical agents, impervious to bacteria it is a wonderful conserving medium. A bad conductor of heat it is a perfect insulator of electric currents. Weather can do nothing to it —it is unspoilable. In 1874 the steamship Nile was wrecked off the coast of Japan carrying a cargo of lacquered goods. After 18 months’ immersion the object - , were re-

covered in a perfect state of conservation. It has also been proved that neither mineral oils nor ozone, not even fluor-hydric acid can cause it to soften. A dish of lacquered pyrex containing the latter corrosive showed no ill effects and the lacquered laboratory utensils did not deteriorate though brought into daily contact with nitric solutions. These facts are worthy of the attention of all research laboratories and factories. Lacquer can be used for many purposes. During the Great War its striking superiority over synthetic varnishes was demonstrated. Aeroplane propellers, valves, and the fabric of balloons were lacquered by IndoChinese specialists. Being impermeable to gas, it was also used to make gasmasks more effective. For wine casks, beer barrels, etc., lacquer is an ideal covering assuring the perfect conservation of the- liquids. An industrial future may be in store for it as a protective agent for the keels of ships and submarines against corrosion and fouling due to molluscs. One striking example of the use of lacquer is the beautiful lacquered saloon of the Normandie which offers complete security from fire. Raw latex contains two distinct bodies —laccin and laccol. They can be easily separated by precipitation in alcohol or acetone. The laccin possesses powerful oxidizing qualities. By applying the same process to the latex of Melanorrhoea one obtains moreacol, a sort of diastasic gum similar to laccin. Laccin and moreacol, in addition to their other properties, are very toxic. This renders the handling of them difficult and hinders their general use. They give off emanations which cause erysipelatic ulcerations which last from one to two months according to the sensitiveness of the individual. “Varnish boils” or the “lacquer disease” is well known among Asiatic artists and craftsmen. Knowledge of the chemical composition of laccin and moreacol will help to explain the biochemic phenomenon of oxidation so frequent in living organisms. It is to be hoped that the use of these products will become more common in the near future and that the vegetable lacquer of Indo-China will take the position it deserves in the varnish world.