New Evaluation of Water Repellency of Wood by Contact Angle

J. Rak

Abstract


A new method for laboratory evaluation and screening of water repellency of preservative-treated wood surfaces is outlined. The method consists of the measurement of the contact angle of a small volume of water resting on the surface of the wood, under exactly defined, reproducible conditions.

The changes of contact angle plotted against the time of exposure (until the water disappears in the tested surface) provide a "water-repellent curve." An area between this curve and both coordinate axes (so-called "water-repellent area") is measured in minute-degrees and provides a basis for the water-repellency rating. An empirical rating is proposed in eight grades from zero repellency to absolute repellency.

The method is applied to the grading of white spruce and red pine treated with various water-borne preservatives and to white spruce treated with a methylene chloride solution of pentachlorophenol.


Keywords


<i>Picea glauca</i>;<i>Pinus resinosa</i>;preservatives;preservation;test methods;surface treatments;inorganic salts;pentachlorophenol

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