Laboratory hiding power measurements of architectural coatings generally employ blade-type applicators that lay down films of highly uniform thickness. But practical applicators, such as rollers, pads, and brushes, typically apply films that lack uniformity due to incomplete leveling, resulting in the practical hiding power of most paints being less than that measured on films applied with a drawdown blade. This test method simulates practical application procedures and conditions so as to provide an indication of the actual hiding performance obtainable when a paint is applied by an experienced worker. It is not intended to duplicate painting as done by the average consumer.

Since the rheological characteristics of a paint and its interaction with the applicator are influencing factors, rank order correlation between this test and one done by drawdown might not be obtained.

FIG. 1 Practical Opacity Chart in Accordance with Footnote 5 and Appendix X1

1.1 This test method measures the ability of a paint to hide or obscure a surface to which it has been applied by a practical application procedure. This test method covers the use of a paint roller, but the concept is expected to work equally well when the application tool is a paint brush or paint pad.

1.2 The values stated in inch-pound 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 concernss, 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.