AGELESS LACQUER

Evening Star, Issue 22892, 25 February 1938, Page 7

AGELESS LACQUER

MAY BE USED FDR MANY PURPOSES There are. two natural products bearing the name of lacquer which both originate in the Far East; gum-lacqiier ana the . latex of certain trees, writes Georges Brooks in La Nature, Paris. GumJacquer '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 alcohol 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 Bhus-vernicifera in China and Japan, the Bhiis sucoedanea. ,in Tonkin and the Melanorrhoea laccifeya 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 more 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 the 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 objects were recovered 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 deteriorate though brought into daily contact with nitric solutions. These facts Are worthy of the attention of all research laboratories and factories.

Lacquer can. bo used for many purposes. During the Great War its striking superiority oyer 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 maike gasmasks more effective. For,wine casks, beer barrels, etc., lacquer is ah 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 end submarines against corrosion ancq 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 5 is well known among Asiatic artists arid craftsmen. Knowledge, of the chemical composition of laccin and moreacol will nelp to explain the biochenaic phenomenon of oxidation so frequent in living organisms. It is to he 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.