I recently watched Wheeler Dealers on TV and they treated a Mazda with a paint on rust remedy which apparently dissolves rust. Anyone have any ideas what this product is?
I used to restore cars as a hobby. Then I owned a chauffeur company for 12 years and I usually had to repair and repaint cars I'd bought before they were acceptable for chauffeur work. I used several rust converters in the early years and I never found any of them to be effective. The rust always seems to come through again. I found the only real way to eradicate rust was to grind it out with a cutter or stone then repair the holes or gaps with new metal, lead loading and body filler.
The rust converter most people recommend today seems to be Hammerite's Kurust. I used it last year on a set of steel wheels which I then painted with Hammerite. The rust is starting to come through again!
If you are thinking of buying one of the rust converters Tangojoe just bear in mind they are expensive and never 100% effective. Your best bet is to cut the rust out and let in new metal or use filler. Good luck!
Don't be timid, as Andy says grind away every bit of rust you can, then use kurust doing what it says on the tin and then hammer the metal back well below the suface and coat and build back with fibregass resin and fine matting, then filler and then paint.
Khandro - Not wishing to be accused of bad analogies I always saw repairing rust as a surgeon does when they tackle cancer. Rust can be regarded as metal cancer. In the same way as a surgeon must cut out every cell otherwise the cancer returns in a patient, the only chance to save a car is to be brutal and cut out every speck of rust, otherwise it will just come back and kill the car.