This specification covers the performance and qualification requirements for rigid exterior 2-component urethane clearcoat systems used over high solids solvent borne basecoats. Typical volume solids as sprayed are 45 to 50% for basecoat and 50 to 60% for clearcoat. This topcoat system is intended for rigid or semi-rigid substrates painted outside of the assembly plants.

Material Description. Basecoat components of these systems are typically 1K (solvent) acrylic melamine. Clearcoat components of these systems are flexible, 2K (solvent) urethane or urethane blends. Each combination of specific basecoat and clearcoat must be tested and approved as basecoat/clearcoat system. The individual components are not interchangeable. In addition, the topcoat system must meet qualifications set forth in this specification and those shown on engineering drawings. Validation testing for plant specific layering, ancillary materials, and processing must be conducted prior to release.

Qualified to this Material Specification. Each combination of specific basecoat and clearcoat must be tested and approved as a basecoat/clearcoat topcoat system. The individual components are not interchangeable. In addition, the topcoat system is part of the total coating system and must meet qualifications set forth in this specification and those shown on engineering drawings for appearance and durability.

Symbols. Not applicable.

Typical Applications. These topcoats are designed to be applied over a baked primer.

Remarks. Not applicable.