【国外标准】 Standard Test Method for Evaluation of Tannin Stain Resistance of Coatings

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.1.1 This test method is an accelerated procedure to determine the effectiveness of latex coatings at preventing the migration of tannin stains from wood substrates.1.2 The values in SI units are to be regarded as the standard. The values in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.