Basicly it's a phosphoric acid treatment, I think the absolute best way to explain it would be for you to read about it. Try this link and it will give you an over view. http://en.wikipedia.org/wiki/Phosphate_conversion_coating

Your automotive paint dealer can supply you with a phosphate conversion coating, in the case of PPG which I chose to stay with it's DX520, here is a spec sheet on it: http://www.bapspaint.com/docs/psheets/PPG/Automotive/Deltron/P-226.pdf
Denny Graham

Denny G
Sandwich, IL