ASTM D645/D645M-97(2002)

1.1 This test method covers the determination of the thickness of paper and paperboard except electrical insulating papers (see Methods D 202).

1.1.1 Because of the relatively high pressure 50 kPa [7.3 psi] used in this test method, it may not be suitable for measurement of tissue or other soft or low density materials, because the structure may collapse (decrease in thickness) at the prescribed pressure of 50 kPa.

1.2 The values stated in either SI units or in other units shall be regarded seperately as the standard. The values stated in each system may not be exact equivalents; therefore, each system must be used independently of the other, without combining values in any way.

1.3 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.