Durability Of Natural Wood Finishes Doubtful

Press, Volume CII, Issue 30106, 15 April 1963, Page 10

Durability Of Natural Wood Finishes Doubtful

(New Zealana Press Association)

WELLINGTON, April 14. A water-repellent oil stain has been found the “most promising” natural wood finish for exterior use in experiments by the Dominion Laboratory of the Department of Scientific and Industrial Research. Most finishes tested lacked durability, said Mr R M. Sinclair, the principal scientific officer Oil coatings tailed rapidly and were subject to discolouration by the growth of mould. Varnish coatings had a somewhat longer life—about 12 to 18 months—but failed in an unsightly manner which made renewal of the coating difficult Varnish tended to develop white patches due to detachment of the film from the wood The whole coating had to be removed to restore the surface. The laboratory’s findings in New Zealand were much the same as those in overseas countries where an extensive search has been made for a

durable clear exterior finish Mr Sinclair said.

The most promising type of coating was a water-repellent oil stain. This could be obtained in colours such as redwood and cedar. It was applied as a single coat anc had a soft satin finish. Although tests on native New Zealand timber had been disappointing, it was proba6le it would last better on the absorbent timbers—such as cedar—for which it was originally developed. The coating could be renewed with the minimum of effort. Mr Sinclair said any wood that had been coated would tend to darken under the influence of light and so the initial attractive appearance would decrease slightly with age. Where a home owner, or builder, wished to use a natural finish outdoors. Mr Sinclair advised that the work should be restricted to small areas of wall surface with a reasonably sheltered easily accessible area for maintenance.