GMW GMW14700 PDF

Purpose.

This standard describes the test procedures to evaluate the stone impact resistance of organic coatings. It is applicable to coated metallic, plastic, or composite materials. Method A is a contained method where the gravelometer is contained in a constant temperature freezer and Method B is the transfer method where test panels are transferred from a freezer to the gravelometer at room temperature. Method C is a contained method where the gravelometer is contained in a constant temperature room. If this standard is used on uncoated panels (e.g., molded-in-color (MIC) plastic), alternate evaluation and rating procedures will be required.

Method A: A cold room or freezer of sufficient size in which the gravelometer and the test samples can be maintained at (-18 ± 2) °C.

Method B: A freezer in which the test samples can be cooled to the test temperature of (-18 ± 2) °C. Preconditioning that causes frost on the surface of the test specimens must be avoided.

Method C: A room in which the gravelometer and the test samples can be maintained at (22 ± 5) °C.