Preparation for Powder Coating

Question:

What treatment is best before applying a clear solvent-based lacquer or a powder coating on zinc-plated steel?

Answer:

A paper by P.R. Parker published by P&SF in October, 1979, stated emphatically that substrate surfaces must be clean before the application of powder coatings. He also recommended using a phosphate or other conversion coating in the preparation cycle, before drying and applying the powder coating. If the powder coating is applied to zinc-plated steel, a thin chromate conversion coating is suggested. A chromate film is an excellent basis for securing good adherence of clear organic coatings, but a thick, powdery chromate coating should be avoided .