[Ironangel]

Phosphoric acid is the "active ingredient" in most all "rust converters"...I bought a gallon of the stuff at The Home Depot years ago along with an inexpensive plastic 1-gallon sprayer. Spray the rusted areas with the Phosphoric Acid solution and allow it to dry. The rusted areas should turn into a hard black crusty surface compound. Hence the term "converter" as the rust, (iron oxide) absorbs the phosphorus from the solution to create an inert compound known as "iron phosphate"...Pink Navel Jelly is glorified phosphoric acid in a pretty pink jelly...Do your research. Epoxy coatings are only good after a converter has been used first otherwise the rusting process will continue underneath the coating. The same is true for powder coatings as well. Unless the rusting (oxidation) process is stopped either chemically (by converting it into an inert compound) or physically (by grinding away completely) the rusting will continue.