Reducing Extractives Stain in Western Red Cedar Sidewall Shingles
One of the aesthetic challenges that western red cedar shingles face is extractives redistribution stain, particularly in unpainted sidewall applications. Dip and pressure treatments with a mixture of quaternary ammonium compounds and alkyl amine oxides were investigated for their ability to prevent this stain. After nine months of exposure in Vancouver, extractives stain was present on nearly all untreated shingles, but was greatly reduced in incidence and intensity on both the dip- and pressure-treated shingles. Longer-term potential benefits (increased durability) and risks (accelerated weathering) of these treatments should be investigated.
Keywords: alkyl amine oxides, extractives stain, quaternary ammonium compounds, shingles, Thuja plicata, Western red cedar