This standard contains requirements for three performance levels of primer coatings used to protect ferrous substrates that contain zinc as the major pigment component. Individual products meeting minimum perfor- mance requirements of this standard may vary in formulation, raw materials, and application characteristics. The specifier selects the appropriate performance level. If no Level is specified, Level II becomes the default. SSPC-Paint 20 is a formulation-based standard for inorganic or organic zinc-pigmented coatings that includes options for specifying higher zinc loading levels in the dry coating film,