Just bought a pair of quarter panel scoops for my 71 Challenger. chipped areas indicate they've been through at least 5 different pain jobs over the years. Aircraft Paint Stripper peeled up the very top coat and that was all.

Had bad luck with sand/bead blasters blistering pot metal.

What's the best way to clean up parts like this?

Crushed walnut shells? I would think any type of media that does not create heat.

I've used "Super Clean" it's a purple cleaner/degreaser from walmart... cheap and softens/strips paint on metal easily. Just soak in the stuff for a while and rinse/wipe off.

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"blistering" pot metal ... seriously ?! I blast pot metal often enough and have never had that happen. My guess is what you think are blisters is actually corrosion that's been blown away. Corrosion is very common on exterior pieces.

Unless paint is fresh, I've never seen a stripper that will take off 5 layers. Hell, most won't even touch epoxy primer! If you don't want to blast them, keep at it with the stripper. Or try a d/a sander.

One application of stripper will not take off 5 layers of paint. Keep trying.

Apply the aircraft stripper again and put it in a heavy plastic bag & tie it shut.It will not evaporate this way and will soften more of the paint. Be patient,a few hours or overnite to set.Pull from bag,scrape with a plastic scraper,or carefully with a razor and repeat as necessary.You can go over it with paint stripper and a scotch brite pad to finish,then wash with water to neutralize.Fine blasting can clean and detail it for paint prep.
RT

I agree with the stripper idea. The key ingredient in it you're looking for is "methylene chloride" aka "dichloromethane" which will strip even industrial epoxies, urethanes, acrylics..... all paints that I know of. It doesn't work fast (a few days maybe) & it is KNOWN to cause cancer, so don't do this in closed garage... and wear thick, rubber "dishwashing" gloves.

You can lay some clean mechanics rags after you apply the stripper to help prevent evaporation also if you want to continually work on them.. Apply some stripper to the rags also to keep them wet....

I'm an engineer and have spent many years with die-cast zinc parts, commonly known as "pot-metal". The blistering issue is created from voids (trapped air) in the die cast part and blasting the part causes air that is close to the surface to heat up and expand. Often you will see delamination of the surface as well but that is usually at a low enough level that it doesn't cause cosmetic problems. The same blistering symptom can also be seen when heating die cast parts for any secondary process such as with the powder coat curing process.

- EM

"blasting the part causes air that is close to the surface to heat up and expand" Again, seriously ?!?!? Just how much heat are we talking here ... are you blasting with air pre-heated in a blast furnace or what? The jet of air from the blaster is cooling the part as fast as the friction is heating it. I've never had a blasted part that was even "warm" to the touch. I know for a fact sheet metal will warp from sandblasting but blistering pot metal in a blast cabinet is a little hard to believe. And IF that's happening then you need to change your technique !!!

Talk to your plater...

This would be my suggestion also. Plastic bag or wrap in plastic. Give it some time and it really helps. Even an hour helps... apply goop, wrap it up, gently scrape and repeat if needed.

If it was me I would just use a da and be done with it.

Either brake fluid or lacquer thinner, in a sealed, closed container. Submerge the parts, seal, and walk away for a few weeks. Carb dip may also work.

Brake fluid seems to work on non-epoxy paints.