General Motors Company

Outdoor Weathering of Automotive Exterior Materials - Issue 2; English
 N GMW14873

Annotation

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 procedures for evaluating the outdoor weathering properties of materials used on the exterior of the vehicle. These include paint materials, miscellaneous finishing materials for components or assemblies, and abrasion resistant optical finishes for lenses.

Specimen exposure should duplicate the most severe conditions that may occur. Unless otherwise indicated by the responsible engineer, Procedure 1 is used for all paint materials (liquid, powder or laminated films); Procedure 2 is used for applied parts and components and special paint or coating evaluations; and Procedure 3 is used for clear lens coatings. There will be no substitution of other types of exposure apparatus from that specified by the responsible engineer.

Procedure 1: Black Box exposure at a fixed angle of 5 degrees from horizontal facing due south. The paint or coating is applied to 100 ? 300 mm metal or plastic panels for exposure. Flexible test samples or small samples such as emblems may be mounted to metal panels by any method which will ensure that they remain attached throughout the specified exposure period.

Procedure 2: Special Tests. These are established on an as-needed basis by the responsible engineer to duplicate end-use conditions. Examples are in-service position of large assemblies or components that cannot be accommodated on the black box; evaluation of coatings or metal treatments (anodizing, chrome plating, etc.) at exposure angles other than 5 degrees south; use of different types of exposure racks and conditions (i.e., 45 degrees south plush salt water spray to duplicate corrosion conditions, or open rack exposure as described in SAE J1976). Other examples are test apparatus that track the sun with mirrors with/without additional water spray.