This standard covers the minimum performance requirements for an exterior non-weatherable primer used on plastic substrates. This standard is to be used in conjunction with an appropriate 998XXXX painted product specification for primer technology approval. Primers covered by this standard may be either one component or multi-component materials.

Material Description. This primer is part of the total painted product system and must provide a smooth, adhesion-promoting coating direct to substrate or in-mold coating and to subsequent coatings.

Specifications Qualified to this Material Specification. This primer is part of a total painted product system and must meet requirements set forth in the specifications for other materials with which it is used. This specification shall be used in conjunction with the Approved Paint on Plastics Systems (APOPS), a section of the Materials Specifications file (MATSPC), which lists approved substrate, cleaning, priming, and topcoat combinations. APOPS test requirements are defined in GM4497M.

Typical Application. Primers covered under this specification are typically applied as liquids. They are applied direct to a plastic substrate or over an in-mold coating. They are used under an approved topcoat system. In some applications, a primer surfacer may be applied to the parts primer prior to topcoat application. Primers tested to this specification are not approved for a wet-on-wet application with topcoat.