Solvent for removing primer?

[sballard]

When I stripped the paint off my car initially, I painted the bare metal it with cheap rattle can primer to keep it from rusting. Now I need to strip off the primer to lay down body filler. The weld-through primer comes right off with brake cleaner, but the red primer (rustoleum or duplicolor) doesn't. I really HATE to go back to the aircraft stripper to get this stuff off after I already stripped the entire car with it before. Any recommendations?

[962porsche]

Steve
the weld thru primer wipes right off because its solvent is acetone and the solid is Zink because of were and how you are supposed to use it they do not add in products like methoxy , propanol , xylene that bite into metals .

because the rust oleum primer you used does have some of the conponents along with oxide it wil bite into the substraight ( metal ) a little better .
it is still what is called a reversible product because there is no catalyst ( hardener ) you added it the primer so it will in fact wipe off . but because unlike the weld primer there is also talc that is used as a filler or build material . that is what gives you some thing to sand with out being able to just sand right thru quickly .
you will find if you take a cloth rag and soak it in a sovlent ( acetone or thinner ) it will then turn back to a licquid that is why it's called reversible .
at this point if you do try and just wipe it off the panels you will go thru more rags than it's worth .

i would sand it off the panels with 80 grit on a DA sander then change to 180 grit after you remove 99% of the primer . the down side is you will have to remove all the primer from the car in every nook and cranny . if you do not when you top coat the car the reversible primer that is left on the car could and will do things to the top coat you will not like .
it could lift , srink in , peal , ring out when you do put a top coat over a spray can product .

you may find you will be using up quight alot of sand paper removing the primer you sprayed on the panels . it may clog up the paper very fast .

you should have used a catalysed E-Primer ( epoxy or etch ) with a primer like that you can do your body work over the top of it and it would give you better metal protection .

[sballard]

Thanks for the reply. My plan was to coverup each body section I stripped with cheap primer as I went along to prevent flash rusting. Then, remove the primer in sections, fill in the places that needed it, and then laying down the epoxy primer. The red primer does get soft with the brake cleaner and I can get a lot of it off with a scraper. I just thought there might be a better solvent. By thinner, do you mean paint thinner or lacquer thinner?

[962porsche]

paint thinner is lacquer thinner . all thinners are lacquer based products .
because what you have sprayed is a acetone based product i would tend to use that .
the thing is the primer you sprayed really does nothing at all . yes it will slow down some surface rust but if there is enough moisture in the air primers like that do nothing to stop rust . that is not what they are made for they are a build or fill primer . though not very good at it they are non the less in that class of primers .