Abstract
The weathering resistance of a film forming type clear finish on Douglas-fir plywood pre-treated with polyethylene glycol (PEG) solutions was assessed by exposing coated specimens for two years at six test sites (Hokkaido, Tsukuba, Toyama, Kyoto, Kagoshima and Okinawa) in Japan. Pre-treatment with a 1% solution of DDAC did not. work to prevent surface failure of the clear film. A 10% solution of PEG as a pre-treatment showed excellent results for preventing film failure on the clear finish at all exposure test sites. This was likely to be due to properties of photo stabilization of wood surfaces by PEG. Pre-treatment with a 30% solution of PEG, however, showed, delamination of the clear finishing exposed at Hokkaido, Toyama and Okinawa. Since PEG is a high moisture absorptive reagent, the treated wood absorbs much moisture during exposure test where are much snow in winter (Hokkaido and Toyama) or high temperature and humidity (Okinawa). Climatic conditions of exposure test site influenced the weathering ability of film forming type finishes on wood treated by PEG as a pre-treatment.
