Tri-Sodium Phosphate

[njsteve]

BTW, I bought a gallon of Phoshoric acid at Home Depot a month ago. I have been using it to kill the rust on the frame under my 1995 Suburban. Works great at 100% strength sprayed from a plastic spray bottle and left to dry on its own. The metal turns grey after the rust is killed. It also has directions on the jug for paint prep use, if I recall correctly is a 30% solution with water, sprayed on the metal, allowed to sit for a half hour and then rinsed off with water and dried.

(I wasn't about to waste gallons of Evaporust on the truck frame given that it was so crusty looking)