When finishing a product, it is important to remember that the coating is only as good as the substrate.
For the powder to adhere to the substrate, it must be free of rust and/or mill scale.

Removing Rust and Mill Scale

There are 2 basic ways of removing the rust and/or mill scale: chemically or mechanically. At Keystone Koating, we mechanically strip the parts of rust and/or mill scale by grit blasting.  At your request, the steel mill can provide steel without mill scale, in the form of cold rolled or pickled & oiled (acid cleaned and lightly oiled to prevent flash rust). The pickled and oiled process, also known as P&O, is an example of a chemical stripping.

Pre-treatment Process

The pretreatment cleaner we use is designed to remove the oil that is applied in the P&O process, thus the need
for blasting is eliminated. After the part is free of rust and mill scale, we pre-treat the part with an alkaline cleaner to remove oil and/or foreign materials.

After passing through the cleaning stage, the part is rinsed to remove the excess cleaner. The part then enters the iron phosphate stage. This stage etches the steel and applies a layer of crystals on the surface to provide excellent adhesion.  After the iron phosphate, the part is rinsed and dried. The part is now ready to coat.

The pretreatment stage is part of the coating process that can go unnoticed and some think it is not necessary,
however, it is an absolute necessity to achieve optimal rust prevention and years of rust-free use.