ASTM D6686-01(2013)

5.1 Tannins and other chromophoric extractives are naturally occurring materials in wood and wood-based substrates. Tannins are prevalent to a high degree in cedar, redwood, oak and to a lesser degree in white and yellow pine. Tannins are also present in varying amounts in wood composition products. These extractives are solubilized and darkened in color by aqueous coatings, resulting in unsightly yellow or brown discolorations. This test method is designed to show the relative ability of paints to prevent tannin bleed-through. Typically cedar or redwood panels are used for this test.