Proper surface preparation is the single most important factor in the success of a Convoy application. No matter what type of surface, it must be completely free of dirt, oils, and greases.
Minor concentrations of oil and grease can be removed with a solution of our #910 Washing Compound (or trisodium phosphate) and water. Mix 8 oz. of compound to each gallon of warm water. A gallon of solution should clean about 400 square feet of surface. After cleaning, test with scotch tape. If it sticks, the surface is oil free.
Whenever concrete is soaked with oil (i.e., garage floor), it is necessary to remove all oil prior to applying Convoy. Removing only the oil on the immediate surface is temporary as the oil beneath the surface will continue to migrate upward, creating an adhesion barrier.
Oil soaked concrete can be cleaned using our #850 Oil Gone or equivalent oil remover. It may be necessary to soak the surface several times with Oil Gone mixed with sawdust to draw the oil to the surface. When a blotter (paper towel, etc.) can be weighted down on the floor overnight without discoloration, oils have been sufficiently removed.
Remove dirt, grease and oils, as described above. At that point it is best to acid etch concrete. Acid etching with muriatic acid will open millions of tiny pores and permit penetration of Convoy, greatly improving adhesion.
To acid etch the surface, mix one part acid with one part water in a plastic bucket. (Note: To avoid eye injury, always pour acid into water. Never pour water into acid and always wear protective eyewear.) Liberally brush the acid solution on the surface. The acid will bubble on the concrete when applied. When the effervescence ceases, rinse the solution off with clear water. The surface should feel like fine sand-paper when properly etched. Then wash the etched surface with a solution of #910 Washing Compound (trisodium phosphate) to neutralize any remaining traces of acid. Rinse off with clear water, let dry, and the concrete is in perfect condition to apply Convoy.
Remove all dirt, oil, and grease. Remove rust with #970 Rust Remover. Rust may also be removed with an electric buffer equipped with a coarse garnet sanding disc. After cleaning, if the metal surface is polished or unusually slick, it is difficult for the primer to secure adequate adhesion. For best adhesion, these slick surfaces should be marred or scratched with an electric sander equipped with coarse carborundum type paper. Be sure all metal dust is brushed or vacuumed away prior to application of primer.
Preparation of aluminum is similar to metal. After thoroughly cleaning and degreasing, aluminum should be scarified by sanding with heavy grit paper. This will help create a strong mechanical bond.