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This one-page technical data sheet covers P-309 Rust Converting Primer, an acrylic-carrier primer. The sheet says it converts red hematite rust into black magnetite, forming a hardened surface for coating without mechanical removal. It is listed for silicone or acrylic systems on heavily rusted metal, and acrylic topcoats need a clean water rinse first because of the primer’s acidic formulation, with a pH of 4, nominal.
Loose rust, scale, flaking paint, grease, oil and other contaminants must be removed by wire brushing, grinding or power washing, and sound tightly adhered rust may remain. The sheet says not to apply over galvanized, painted or non-rusted metal. Application is between 50 and 120 degrees F with no rain, condensation or freezing expected during cure. Conversion takes about 24 hours at 77 degrees F and 50% relative humidity.
Listed values are 8.8 pounds per gallon, 65 KU viscosity, 48% solids by weight, VOC below 50 g/l, and clear white color. Coverage is 0.25 to 0.5 gallon per 100 square feet at 4 WFT. Packaging is tote, drum, 5 and 1 gallon, and 12 quart containers, with a two-year shelf life. The sheet states that the primer is not intended as a standalone coating.
Material changes / notes
Use this component sheet with the complete roof-system specification. Follow the preparation, application and cure instructions for the selected substrate and coating layers.