Zinc phosphating is best used on products which require maximum resistance to corrosion combined with excellent paint adhesion. Zinc coatings absorb oil, which prevents scuffing of metal parts during manufacture or assembly. Depending on the intended purpose of the finish, the crystal size, shape, coating-weight, and colour can be modified to meet many industrial military specifications.
Lightweight zinc phosphate coatings can be obtained through spray coatings or immersion and are generally used as a pre-treatment to provide an adhesive surface for paint. This light coating (of between 0.3 and 1 micron in diameter) also provides a maximum resistance to corrosion.
Medium-Weight zinc phosphate coatings are normally used as a lubricant carrier for less severe cold-forming operations like tube drawing or sheet reduction.
Heavyweight zinc coatings have a much more defined crystalline structure which can be up to 200 microns in diameter. This thicker coating is best for products which require addition of rust preventative compounds, heavy duty lubricants or soaps