The AUSubaru.com.au Forums

http://www.duluxprotectivecoatings.com. ... erters.pdf

found this from dulux , sort of makes sense, a right of reply as such on a product that may cop the blame from use of another product beneath it.

Do acid makers make a paint they warranty, do paint makers do an acid they warranty ??

Very interesting!

the sellers of phosphoric based treatments usually recommend the loose rust be removed with wire brush or blasting. completely removing the rust to shiny metal is useless as the acid needs some rust to enable a conversion to take place.
they also recommend that the coating be allowed to sit for a day or so, then washed off.
i have found that using this method and ensuring the surface is clean and dry after seems to work.
you will see a milky or clouded surface where the acid has touched rust and nothing where it hasn't. sometimes it leaves a glassy surface.
it will not protect non rusted surfaces.
process the surface as usual with primer or etch primer etc.
if there are flakes of rust after treatment it can be peeled off so obviously the underlying surface will not be protected.

If you can mechanically clean the rust then that is the best option. Primers stick best to nice scuffed bare metal.

The only time I would use rust converters is in spots you can't get in to clean with a wire brush etc. Which there should'nt be too many of those spots on a car where you want nice shiny paint.

I am converting the inside of my chassis rails and then coating them with wax to hopefully stop them rusting out and thats (hopefully) the only place I will need to use a converter.

If you do use them just make sure they are thoroughly washed and wiped before you try to paint over them.

hmmm, yes , reading on forums by timber cutters that the white cloudy finish is not good to paint, need the blacked converted bit only. Also reading etch primer is misconception - really only for unsanded metal, maybe only in its factory painted for protection state of tube and flat stock ????

Yeah etch primer is not necessary - it too uses phosphoric acid and can ruin the paint.

2 Pak epoxy primer over bare untreated metal is the way to go.

been sitting on a KBS sampler kit with a wash, a treat and top coat which they say, once sanded can be painted over with whatever - I will need old school acrylic finish. Got some spray putty to build up some areas.
KBS tells me do the wash, do the treat, spray putty then their paint, then my paint.
It will be suck it and see....

Yeah I've got KBS AquaKlean and RustBuster (or whatever they call it) - its just for inside my chassis rails though. I haven't used it yet so I can't comment on it - though they do say one of them (can't remember which) leaves a zinc phosphate coating which is exactly what you want to prevent rust and be paintable.

Wurth rust neutraliser works very well.
If you clean as much as you can off, then carefully paint the very thin Wurth stuff on it, it soaks in and seals the rust.
Then to paint it is a problem, as nothing seems to bond well with it.
Rust is sealed, you end up with black coloured metal, will last for years like this exposed to weather.
Wurth probably has something, but never tried it, just happy with the way it stops rust.
All are a compromise.
Cut it out and be done with it.