Western redcedar is renowned for its decay resistance, but, like most wood products, it requires frequent maintenance in many exterior applications to maintain its appearance. To provide adequate long-term performance in exterior applications, it must be protected against light, water, and disfiguring fungal growth. Colorant treatments, with and without preservatives, were investigated for their ability to limit colour change caused by exposure to accelerated weathering conditions. Treatments with a copper-based wood preservative and with brown pigments substantially reduced colour change due to photo-degradation. Colorant and preservative technologies were further evaluated in a field test to evaluate their ability to inhibit or mask colonization by black stain fungi. After six months’ exposure, the colorant and preservative treatments exhibited little to no effect on black-stain discoloration ratings. The colorants and copper-based treatments did, however, continue to reduce colour change and partially mask black-stain fungal growth.

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