Previous Preservation of Veneers Promotes Higher Preservative Retention and More Effective Protection in CCA-Preserved Plywood

Abstract

Plywood panel has a promising market in Wood Frame Construction System. Like any wood-based product, it can suffer deterioration, and preservative treatment is imperative. The preservative treatment can be done directly on a pressed panel - a conventional method that supposedly causes a decrease in physical-mechanical performance - or incorporated into the production process, by the previous treatment of veneers to develop panels with durability and quality. We compared the performance of these two processes. Panels were produced with Pinus taeda L., using 360 g m-2 of phenolic adhesive in a double line, a pre-pressing and hot pressing for 20 minutes under 1.2 MPa pressure and 130°C and treatement on veneers and panels with CCA-C. Tests followed Brazilian standards. Panels with previous treatment had lower water absorption and swelling. Preservation of the veneers also promoted higher retention levels and better penetration of preservatives. Both treatments did not affect the mechanical performance.