ISO 16862 describes a test method for evaluating the sag resistance of paints, varnishes and similar coating materials (paints) when applied to a substrate and held in a vertical position.
After the coating has been applied, the sag resistance can be assessed as follows:
Use the pendant index applicator on the test board placed horizontally, then vertically;
Apply with Spray Gun on substrate in vertical position.
Tensile sag testing requires a pre-shear procedure to replicate the structural degradation that occurs when thixotropic coatings are applied by brush or other practical application methods. Therefore, the process includes a preliminary cut of the paint before application. The rotational speed and mixing time will be determined by interested parties.
The wet film thickness obtained by application is less than the cavity depth of the applicator, depending on viscosity, rheology and application speed. Therefore, the actual wet film thickness applied needs to be determined and recorded as the largest non-sag void size.
