【国外标准】 Standard Test Method for Determining Enamel Holdout

5.1 This standard may be used by paint companies and raw material suppliers to assess the interactions of primers and topcoats with respect to their ability to provide good enamel holdout. Primer/topcoat systems with the best enamel holdout will result in desirable gloss in the first coat of topcoat application.1.1 This standard provides a method for determining the holdout characteristics of a primer and topcoat coating application. A standard topcoat is used to determine the absorption characteristics of a primer. Enamel holdout can be measured as a difference in observed gloss of the topcoat over a primer, relative to the gloss of the same topcoat over a non-porous, smooth surface.1.2 The standard is written in the context that the user will be evaluating the enamel holdout characteristics of a primer. Alternatively, the standard may be used as a method to evaluate the enamel holdout characteristics of primer/topcoat system where the primer is constant and different topcoats are used as test paints.1.3 This standard may also be used for evaluation of paints other than primers as the first coat. In this alteration the user can test the enamel holdout characteristics of a self-primed topcoat, or use of any other type of paint as the primer followed by the use of a standard topcoat.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 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.1.6 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.