Manganese phosphate
Builds a coarse, dark-grey/black crystal layer, thicker than zinc phosphate, holding a lot of oil to cut wear and run-in friction.
Popular for engine parts, pins and parts that rub directly against each other.
Zinc phosphate
Gives a finer, light-to-mid grey, thinner layer—ideal as a primer before paint/powder thanks to even, strong paint adhesion.
Also used as a lubricant layer to aid cold forming.
How to choose
Friction / heavy oil retention: manganese phosphate.
Paint primer / even smooth surface: zinc phosphate.
Both should be sealed with oil or paint for corrosion resistance.
FAQ
Which protects better?+
Manganese is thicker and holds more oil, so it out-protects and out-wears when oiled; zinc shines as a paint primer.
Which suits a paint primer?+
Zinc phosphate—its fine, even crystals give strong adhesion and a smooth surface.
Does phosphate change the colour?+
Manganese reads dark grey/black, zinc light-to-mid grey; choose by use and looks.
