Free films are required for conducting tests to evaluate physical properties such as tensile and elongation (Test Method D 2370), moisture vapor permeability (Test Methods D 1653), and other physical properties of organic coatings where the substrate may interfere with the determination.

The tin foil/mercury amalgamation procedure should be used only in cases where other substrates may be affected by high-temperature baking or may affect the test results.

1.1 This practice covers the preparation of free films of organic coatings for use in determining the physical properties of the coatings. Procedures are given for preparing free films on four alternative substrates. These substrates are dental foil, treated FEP (fluorinated ethylene-propylene) sheet, silicone coated paper, and halo-silane coated glass plates.

1.2 The values stated in SI 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 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. A specific hazard statement is given in 6.1.