Pretreatment removes oil, shop soil, oxide and mill scale, then usually lays down a conversion coating that anchors the powder and slows corrosion under the film. Lines range from a hand wipe with solvent to a five to seven stage spray washer, plus abrasive blasting for heavy steel. Most adhesion failures and early rust traced back from the field start with a pretreatment problem, not the powder.
Coating's peeling off in sheets, that's not the powder, that's pretreatment. Pull the washer logs.
When a coating fails in the field, ask for the washer titration logs from the run date before blaming the powder supplier.
Also heard as
- pretreat
- prep
Related terms
Conversion coating
A thin layer formed by chemically reacting the metal surface, which improves adhesion and slows corrosion under powder.
Five-stage
Shop name for a spray washer with five tanks: clean, rinse, conversion coat, rinse and final seal or DI rinse.
Iron phosphate
A thin, amorphous phosphate conversion coating on steel, the economical standard for indoor and light outdoor parts.
Water-break test
Quick cleanliness check: a clean surface holds an unbroken sheet of water, an oily one makes it bead and split.
Blast
To strip and roughen a part with abrasive media before coating, or as a noun, the blast room itself.