ASTM D7835/D7835M-13

5.1 Many coatings used in the coil coating and other industries achieve a degree of solvent resistance after they have experienced a bake condition characterized by exposure to elevated temperatures in an oven over time. Insufficient bake, or occasionally over bake, may affect the intended chemical bonds or physical curing of the film and result in reduced solvent resistance.

5.2 The mechanical rubbing machine provides consistent stroke length, rate, pressure, and contact area that are not subject to variables such as human fatigue (see Practice D5402).

5.3 Factors other than bake can influence degree of solvent resistance of a coated surface. Paint film chemistry and composition, surface preparation, oven dwell time, oven air velocity, ambient oven temperature, oven profiling, film thickness, etc., all are influential. The test solvent used in the rub machine has a significant effect on the number of double rubs measured. Common solvents used for these tests include Methyl Ethyl Ketone (MEK), Methyl Isobutyl Ketone (MIBK), and Isopropyl Alcohol to name a few. The specific solvent to be used and the umber of double rubs to be achieved should be agreed upon between manufacturer and user for any given coating system, thickness, and application.

1.1 This test method covers a mechanical rub method for assessing the solvent resistance of an organic coating that chemically and/or physically changes during the curing process. This technique can be used in the laboratory, in the field, or in the fabricating shop.

1.2 This test method does not specify the solvent, number of double rubs, or expected test results.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.