Astm D823 'link' May 2026

1. Scope & Purpose ASTM D823 describes four distinct practices for preparing uniform films of paints, varnishes, and other coating materials on flat test panels. The primary purpose is to ensure that laboratory-prepared coated panels have a consistent, controlled film thickness for subsequent tests (e.g., color, gloss, hiding power, or mechanical properties). Unlike drawdown bars (ASTM D823) that create a wet film of fixed clearance, these practices use precision applicators to control thickness via blade gap or applicator weight.

Example: A 150 µm blade gap applied to a paint with 50% volume solids yields a DFT of 75 µm. astm d823

[ DFT = G \times \left( \frac{VS}{100} \right) ] astm d823