KAURI GUM VARNISH.

Auckland Star, Volume LX, Issue 229, 27 September 1929, Page 7

KAURI GUM VARNISH.

POSSIBLE NEW USE.

SURFACE FOR AEROPLANE WINGS.

That kauri gum resin is termed "hard," that is, is has a high melting point, may be the factor which will open out a new branch in the kauri gum industry.

According to the "American Paint Journal," St. Louis, scientific investigation in the direction of producing a surfacing to aeroplanes which will stand the extreme wear and tear of flight and taxi-ing on land and water, has shown that the only varnish which will stand up to the rough usage is a "hard" varnish. Kauri gum varnish is the. hardest produced in bulk to-day. American authorities are using to a large extent the acetate kind of lacquer, and this requires a harder resin. This could very satisfactorily be supplied by kauri gum.

All classes of aircraft are treated with a surfacing preparation in the course of being built, and for an ordinary sized aeroplane 11 gallons of varnish and 59 gallons of "dope" or undercoating are necessary. In the larger types the amount used is correspondingly greater. By the use of this process, the material of the wings is stretched tight and if ade waterproof, and the harder the surfacing process, the more satisfactory the result. The strength of the fabric is increased by 20 per cent. More than this, the speed of the craft is materially helped, by the application of surfacing. The effective speed of the Curtiss racers used by the United States Government for the Schneider Cup was increased by 5 miles an hour simply by the use of an improved surfacing. Unfinished pontoons give a speed of 174 miles an hour, and when finished give an added speed of six miles an hour. The ideal surface preparation is that which will present no resistance to the wind, and. it is believed that the use of that type of varnish of which the kauri gum preparation i 3 one of the best examples, will help materially to attain that end.