4.1 Free films are required for conducting tests to evaluate physical and mechanical properties such as tensile and elongation (Test Methods D2370 and E96/E96M), moisture vapor permeability (Test Methods D1653), and other physical properties of organic coatings where the substrate may interfere with the determination.
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 three alternative substrates. These substrates are treated FEP (fluorinated ethylene-propylene) sheet, silicone coated paper, and halosilane coated glass plates.