Home>ASTM Standards>ASTM D7072-04(R2019) pdf free download

ASTM D7072-04(R2019) pdf free download

ASTM D7072-04(R2019) pdf free download.Standard Practice for Evaluating Accelerated Efflorescence of Latex Coatings
1. Scope
1.1 This practice covers the evaluation of the degree to which a latex paint resists the formation of efflorescence and alkali burnout on the exposed paint surface. 1.2 This practice is designed primarily to relate efflores- cence originating in the substrate to the deposit appearing on the surface of latex paints. This practice relates chiefly to the painting of masonry-type substrates such as concrete block, brick, mortar, stucco, poured concrete, and similar materials. 1.3 The values in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.4 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. 1.5 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.
3. Terminology (Specific to This Practice)
3.1 Definitions ofTerms Specific to This Standard: 3.1.1 alkali burnout, n—the premature fading or decompo- sition ofpaints that are sensitive to the high pH ofthe substrate. The high alkaline content of the substrate can alter the color. 3.1.2 efflorescence, n—the deposition of soluble salts on the exposed paint surface. Efflorescence is characterized by a light-colored, nonuniform, powdery incrustation which de- tracts from the paint film appearance. The discoloration occurs when soluble salts in the substrate or paint migrate to the surface by the leaching and evaporating action of the water carrier. The efflorescence originating within the substrate is that with which this method is concerned. 4. Summary of Practice 4.1 Panels known to have a level of salts capable of being easily and quickly transported to the paint surface are used. Since tinted paints show the efflorescence most clearly, all white paints should be tinted before application. The panel is placed face down over the surface of the test chamber which contains heated water, so that moisture condenses and remains on the painted surface of the panel for a period of 48 h. After drying at ambient conditions, the panels are rated for the degree of efflorescence which has formed.
8. Procedure
8.1 Mix the cement:sand:water in the ratio as described in Practice D1734. Apply the mix approximately 6 mm ( 1 ⁄ 4 in.) thick over the fiber-cement siding using a trowel. Allow the panels to dry for 24 h or as agreed upon by the purchaser and seller. Divide substrate into strips at least 150 mm (6 in.) wide or as agreed upon by the purchaser and the seller and label the back of each test area with the paint designation. The control paint should be placed near the middle of the panel. 8.2 Prepare paint brush as described in Practice D5068. 8.3 Using a brush, apply sufficient weight of test paints to achieve the desired spreading rate. If a second coat (top coat) is to be applied, allow the first coat to dry in the conditioned room for 16 6 1 h (dry time may affect results) or as agreed upon by the purchaser and seller. Results may be highly dependent on film thickness; therefore, it is essential that the test paints be weighed on accurately, particularly for small test areas. The amount of paint in grams required for a specific spread rate can be determined from the following equation.

Maybe you like

Standards Tags