PHOSPHATING or PHOSPHATIZING

SUGGESTED PHOSPHATING BOOKS
phos_sharma22
"Optimization of Phosphating Process" by Vinod Prasad Sharma (2022)
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phos_rausch1991
"Phosphating of Metals" by Werner Rausch (1991)
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phos_freeman1991
"Phosphating & Metal Pretreatment" by D.B. Freeman (1986)
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Phosphatization (phosphating) is a coating applied to steel and galvanized items by immersion or spraying. It is a conversion coating, i.e., it converts some of the steel or zinc on the surface of the work to compounds which are more corrosion resistant and more amenable to having paint adhere properly or more capable of retain a coating of oil.
     There are almost countless possible tweaks, but most people consider the coatings to fall into 3 general classes: iron phosphate (the lightest/thinnest and best suited to items that will be cold formed after painting); manganese phosphate (the thickest/heaviest and best suited to holding oil, for example as a 'break-in' coating on engine parts & gearing); zinc phosphate (thicker/heavier than iron phosphate but thinner/lighter than manganese phosphate, and well suited to both steel & galvanized items for excellent corrosion resistance and paint adhesion). You can search the site for 'iron phosphating', 'zinc phosphating', and 'manganese phosphating' for dozens of threads about why and how components are phosphatized, and all aspects of the phosphatizing processes.