System 7 Superflex fabric primer (SF7500) is the heart of the Superflite urethane system. It is a high-build, flexible primer with excellent filling and sanding properties, and it replaces the separate fabric filler and silver coats that other systems require.

Mix 4 parts SF7500 primer base with 1 part SF7600 primer catalyst, and reduce up to 50 percent with any 7800-series reducer chosen for your shop temperature. Pot life is about one hour at 77 degrees F. Apply two coats: the first coat is thinner and fills the weave, and the second coat builds. Then sand and apply System 7 topcoat.

Primer base is available in pints, quarts and gallons, with catalyst by the pint.