How to Troubleshoot Powder Paint Pretreatments

Wipe off all metal surfaces to be powder painted with a cotton rag soaked in solvent such as kerosene, benzene or naptha. Change the cloth frequently. Use phosphoric acid to remove stubborn rust, carefully following directions on use of the acid. If all oil, grease and rust cannot be removed in this manner, you will need professional help with abrasive blasting or much stronger chemicals than are commonly available.

Apply a phosphate-based pretreatment chemical to protect and prepare the degreased surface. Zinc phosphating is the most common, and is applied to automobiles, appliances and hardware. Iron phosphating is used when the metal will need to be welded before being powder painted. Completely cover the metal surface with the phosphate solution by following instructions on the container. Often, the metal is dipped into a bath of the solution for one to two minutes. The solution creates a chemical reaction with the metal, which gives good adhesion for paint film.

Rinse the pretreatment chemical off the metal completely. Repeat the rinse process more than once to be sure all the chemical has been removed. Dry the metal thoroughly.

Mask any areas you do not want coated using high-temperature masking tape, caps and plugs. The metal is then ready to be powder painted.