Weathering performance of wood treated with copper azole and water repellents

Abstract

Water borne wood preservatives have been widely used for a long time in the protection of wood either in ground contact or above ground. Copper is still major biocide component used today in treatment plant for wood protection despite the environmental concerns over copper-rich preservative systems. On the other hand, water repellents are considered to be potential additives for biocides, resulting in the decreased moisture content, reduced biocide leaching and increased dimensional stabilization. In the present study, copper azole (CA) was used as wood preservatives to the natural weathering for 6, 12 and 24 months respectively. In addition, semitransparent wood stain was used as post treatment with CA, and paraffin and silicon additives were incorporated in to biocide to be water repellent. Paraffin additives reduced the retention values as compared to other formulations. The highest color change and gloss loss were obtained with Scots pine control samples within the six months. CA pretreatment before wood stain was promising by indicating the lowest color change. Color change was reduced by the increasing ratio in paraffin and silicone additives. Combination of CA with wood stain and silicon additive could reduce the copper leaching to some extent.