The aim of the investigation was to study the prospects
for the development of decay and insect resistant plywood
and particle boards. The treatment of the boards during
manufacture and possibilities of protecting the finished
boards were clarified.
The investigation comprised phenolic glued birch and
spruce plywood and PF- and UMF-particle board. In the
decay tests the reference material comprised different
species of timber and impregnated A- and B-class pine
(SFS 3974). The plywood boards were protected by
treatment of wet veneers with water-soluble diffusible
compounds, by dipping, immersion or spraying of dry
veneers with oil soluble preservatives, or by addition of
preservative to the glue. The particle boards were
treated by spraying the preservative on the chips before
gluing, or by addition of preservative to the glue. The
finished boards were protected by impregnation with water
or oil soluble agents and by coating and edge sealing.
The strength properties, contents of preservatives, decay
resistance to Coniophora puteana and Gloephyllum sp., and
resistance against termites (Heterotermes judicola) were
studied. A greenhouse test was started an the same time
which studied the durability of the boards in contact
The impregnation of finished boards proved particularly
difficult with regard to plywood. The particle boards
were more easy to impregnate, but in both boards the
drying was very slow.
The treatment of wet veneers with different preservatives
gave deviating results. Acidic and oxidacive substances
and barium containing substances weakened the strength of
the glue joint. Wood-based boards almost corresponding to
the A-class impregnated wood in the laboratory tests were
obtained with ammoniacal copper compounds. Of the
treatments on dry veneers the immersion and spraying
proved more efficient against decay than glue protection
treatment. TBTO was both in spraying and immersion
efficient against Coniophora. The impregnation of the
veneers before gluing with CCA-compound weakened glue
joint clearly in concentrations required against decay.
The preservation of particle boards did not influence the
strength properties of the boards. TBTO treatments
protected the boards rather effectively against decay.
However, they did not prevent moulds.
Plywood and particle boards protected by mixing
preservations in glue were in the termite tests
relatively more resistant than in the decay tests, even
though separate treatments with permetrin were more
effective in plywood.
The edge sealing of the plywood board decreased the
leaching of the preservative and even increased the decay
resistance of unprotected plywood. Coating with a
phenolic film and edge sealing with acrylate paint
prevented leaching of the preservative and decay of
treated and untreated plywood and PF -particle board.
|Place of Publication||Espoo|
|Publisher||VTT Technical Research Centre of Finland|
|Number of pages||57|
|Publication status||Published - 1984|
|MoE publication type||D4 Published development or research report or study|
|Series||Valtion teknillinen tutkimuskeskus. Tutkimuksia - Research Reports|
- insect control
- laminated wood