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ASTM D6900-10(R2020) pdf free download

ASTM D6900-10(R2020) pdf free download.Standard Test Method for Wet Adhesion of Latex Paints to a Gloss Alkyd Enamel Substrate
1. Scope
1.1 This test method covers a procedure for measuring by scrubbing the adhesion of latex paints to glossy alkyd enamel substrates after exposure to wet conditions. 1.2 The values stated in SI units are to be regarded as the standard. The values given 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 Test paints, with optional control paint, are drawn down using a 7-mil clearance Dow applicator (~11 m 2 /L) across a cured alkyd gloss enamel previously drawn down on a black or white plastic panel. 4.2 The drawdown films are allowed to dry under standard- ized conditions. Then, eighteen cuts are made to form a 6 by 10 cut block, creating sixty 6.4 mm (0.25 in) squares, in the center of each film with a razor blade. 4.3 The panels are then soaked for 30 min in ambient tap water. The panel is mounted in a washability tester and 20 mL of water are applied. The panel is then scrubbed for up to 500 cycles or until all of the squares within each block are completely removed.
5. Significance and Use
5.1 After application to either interior or exterior surfaces, latex paints may be subjected to conditions of high humidity, condensation, or precipitation. This may sometimes lead to a loss of adhesion to the substrate over which they have been applied. This method is a quantitative measure of the adhesion of latex paints to glossy substrates under such conditions.
6. Apparatus
6.1 Constant temperature/humidity room in accordance with Specification D3924 [23 6 2°C (73.5 6 3.5°F) and 50 6 5 % relative humidity]. 6.2 Drawdown Plate. 6.3 Straight Line Washability Tester and Accessories, per Test Methods D2486. 6.4 Nylon Bristle Brush and Accessories (nominal weight 455 g), having nylon brush bristles in 5/4 pattern extending 19 mm ( 3 ⁄ 4 in.) from block (as per Test Methods D2486).6.5 Dow Film Applicator, having 7-mil (0.18-mm) clearance by 5.2-in. (132-mm) width. applicator blade. 6.6 Single-edge Razor Blade, in safety holder. 6.7 Metal Straight Edge (or appropriate guide).
7. Reagents and Materials
7.1 A ready-mix deep-tint alkyd gloss enamel with a 60° gloss of at least 65 as measured in accordance with Test Method D523 (or alkyd as agreed upon by the purchaser and supplier). 7.2 Plastic test panels as used in Test Methods D2486. 3
8. Procedure
8.1 Preparation of the Alkyd Substrate Panels—Attach the plastic panel to the drawdown plate and drawdown the alkyd gloss enamel lengthwise using a 7-mil clearance Dow appli- cator. The time for application should be fairly slow—3 to 4 s from end to end. The drawdown must be free of ridges, holidays, specks, or other imperfections, which may affect adhesion. 8.1.1 Allow the alkyd gloss enamel to air-dry in a horizontal position. Allow to cure typically for a minimum ofthree weeks. Panels are to be used between three to six weeks from the date of preparation. Wet adhesion with some latex paints may be dramatically reduced if the alkyd is allowed to cure for more than six weeks. 8.2 Application and Evaluation ofTest Paints: 8.2.1 Attach the cured alkyd enamel-coated plastic panel to the drawdown plate and simultaneously drawdown test paint and an optional control paint side-by-side using the 7-mil clearance Dow applicator. The time for application should be fairly slow—1 to 2 s from edge to edge. Each drawdown is made perpendicular to the length ofthe panel and positioned so that the drawdowns are contiguous (See Fig. 1). N OTE 1—Typically a control paint of known wet adhesion is recom- mended for use in the method to limit the variability of results from test to test.

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