GMW14700

Description / Abstract: GMW14700, 4th Edition, July 2017 - Stone Impact Resistance of Coatings

Introduction

Note: Nothing in this standard supercedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

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 °C ± 2 °C.

Method B: A freezer in which the test samples can be cooled to the test temperature of -18 °C ± 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 °C ± 5 °C.

Applicability. This standard is typically used, but not limited to, exterior applications on the car body for different organic coated substrates. The standard can also be used for other purposes, e.g., as preload of organic coated metallics in front of corrosion testing such as chassis parts, underhood parts, etc