The Stovebolt Site Forums The Shop Area Paint and Body Shop Rust Bullet?

I USED a couple of similar products down here called "Rust Converter" in Australia. They are both based on phosperic acid and fizzes a bit when applied, when left for a day or so, the rusty surface goes a deep black. According to the blurb, it converts the rusty stuff into Iron Oxide which can be painted straight over, sanded, prepped, primed and away you go.
I used it on a set of GMC fenders and side steps that have been laying out in the bush paddock for some 25 years. A bushfire had been over them at some time and stripped the paint off, they were bare, very rusty metal.
AND they came up OK, you wouldn't know where they had been. If they rust out I'll buy f/glass, at some time in the future, but they'll do me for now.