Resin exudation is a common problem in softwood exterior sidings as softwoods are known for the important quantity of resin or pitch that they contain. Resin exudation accelerates the weatherability of siding by forming cracks or blisters. The use of cool color pigments could help reduce the resin exudation on exterior wood sidings as so, it would improve the durability of the products and make the wood more competitive on the market compare to canexel, PVC, etc.
Cool color pigments are characterized by high solar reflectance and thermal infrared (IR) emittance values (Synnefa et al., 2006) and they can help reduce the heat buildup in materials by reflecting some of the solar radiation.
In this project, IR-reflective pigment coating was applied as a primer, and then other coatings were applied as topcoat on PVC and white pine. Color and heat buildup measurements were carried on the two substrates. The results reveal that an IR-reflective primer could be efficient in some cases. In another part of the project, coatings of three different colors were prepared from two set of pigments, conventional ones and IR-reflective pigments. Color measurements, heat buildup measurements, total solar reflectance and resin exudation evaluation were realised on three different substrates (PVC, white pine and black spruce). It was found that IR-reflective pigments lead, for the three colors, to lower heat (IR) absorption.
However, resin exudation experiments were not conclusive.