Topcoat, Generic Qualification
|Publication Date:||1 January 2021|
This specification details the minimum performance, compatibility and processing requirements for international approval of all exterior topcoats.
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.
Materials qualified to this standard shall meet the performance requirements shown in Appendix A, Table A1 for the specific topcoat type. Appendix A summarizes all requirements for material technology approval. Additional testing or any exceptions to the requirements may be directed by the GM approving engineer. Suppliers must demonstrate that the material technology is production capable via successful trial completion in an agreed upon paint facility prior to use for GM production parts or vehicles. Any material development performance issues or values that fall outside specified ranges must be discussed with the responsible topcoat materials engineer for resolution.
Note: Line trials may begin after 2 years of Florida exposure.
This specification applies to all exterior topcoats for use on vehicles or parts supplied to GM. Topcoats and their performance levels are defined by Type and Class types.
The topcoat type defines the requirements for test panel preparation, basic testing, compatibility testing and processability for use in a specific application.
Table 2 defines the topcoat classes. The topcoat class defines durability, performance and appearance requirements. For this specification, durability is determined by weathering performance (Florida exposure and accelerated weathering tests). Performance is defined by environmental fallout and chemical resistance, scratch resistance and chip resistance. The appearance requirements are defined by GMW15777 appearance standards developed for each vehicle segment. Collectively, these characteristics determine if the material will perform to its intended function under specific conditions through its product lifecycle. Specific requirements are defined in Appendix A. If any of the criteria for a specific class is not met, the classification will be lowered to the appropriate class.
The material must meet or exceed requirements as defined in GMW15777, including specifications for gloss, Distinctness of Image (DOI), R value (orange peel), Long Wave (LW), Short Wave (SW), and uniformity. Provide a film build appearance curve that demonstrates the film build required to achieve the optimum appearance.