1.1 This test method covers the quantitative determination of the resistance of paper surfaces to wetting by measuring the behavior of a drop of liquid when applied directly to the paper surface.

1.2 The procedure described in this test method involves the measurement of the angle of contact. Both the initial wettability and the rate of change of wettability may be measured.

1.3 When using a standard ink, the initial contact angle or wettability is considered to be a measure of the ruling quality of the paper. The rate of change of contact angle or wettability is considered to be a measure of the writing quality.

1.4 Other liquids, both aqueous and nonaqueous, may be used with this technique in special applications. Modification of the procedure may be required when using liquids other than the standard ink described.

1.5 Two types of apparatus for measuring the contact angle are described. Additional apparatus that can perform the test may also provide equivalent results.

1.6 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.7 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.