Most frequently, iron phosphate is used to pretreat powder coating, but other materials can be used as well. The reason that people choose to utilize iron phosphate is its usability with almost all substrates. Often, powder coatings will show improvements in performance over liquid paint when iron phosphate is used to pretreat.
A more costly process used for higher-end products is zinc phosphate. This process does have downfalls of using heavy metals, producing sludge, and needing added washer stages, yet sometimes is necessary if the desired performance is not accomplished with iron phosphate.
