Iv got a small rust bump on my door sill and want to sort before it gets any bigger, after sanding and removeing any flakes what's a good product to use to stop the rust comming back before painting?
Sanding, wire brushing. or chemically treating the rust is only temporary, so I can't recommend any of them!
Grit blasting, cutting out the rust, and welding in new metal, or panel replacement, are the only surefire ways to successfully eliminate rust.
Your best bet is to grind away the rust, and finish with a thin skim of body filler, followed by etch primer, primer and paint, the more thorough the preparation, the longer it will last
Thom