Bath strength is checked by titrating a standard sample, often 10 milliliters, with a reagent until a color change; the milliliters used are called points. Cleaners, phosphates and acid stages each have a target range on the supplier's control sheet, and operators dose chemicals to stay in it. Free acid, total acid and their ratio are the key points for phosphate baths.
Cleaner's at 6 points, sheet says 8 to 10, so add a drum before the next rack goes in.
Also heard as
- titration points
Related terms
Iron phosphate
A thin, amorphous phosphate conversion coating on steel, the economical standard for indoor and light outdoor parts.
Pretreatment
The cleaning and chemical conditioning a part gets before powder, which decides most of its adhesion and corrosion life.
Five-stage
Shop name for a spray washer with five tanks: clean, rinse, conversion coat, rinse and final seal or DI rinse.
Zinc phosphate
A heavy crystalline phosphate conversion coating that gives steel top-tier corrosion resistance under powder.