Depends on the kind of paint. Cellulose lacquer types are gonna be the worst, even if you could lift the paint off perfectly, the solvents of it would have damaged the surface already. Most plastics are not very affected by regular white spirit type paint thinner or turpentine substitute unless you soak them in it a long time (It makes yoghurt pots soft, (styrene??) but other plasticware stands up to it). Then there's non solvent things that just eat the paint, like caustic soda, aka lye, aka sodium hydroxide, aka paint stripper, aka oven cleaner, aka drano. Some plastics may resist this, some may not.
Here's a chemical resistance chart with common solvents https://www.plasticsintl.com/chemical-resistance-chart no hydroxide on it though...
aha, here's one with it on there as soda lye...
https://www.curbellplastics.com/Research-Solu … nce-of-Plastics

Case plastics are most likely to be ABS. Strength of common caustic soda products goes from weak in hair remover, bit stronger in oven cleaner, stronger still in paint stripper and most strong in drain cleaner.

No solution here, just some bad experience.

I had a long battle last summer with black painted case. I learned with DOT4 brake fluid you can remove some specific type, but it was not very efficient on this particular paint. It was good on some parts of golden drive bay covers. It's also nasty stuff to work with, not recommended.

Gasket remover spray also works on some level, but it might damage plastics so I used it only on metal parts. Also nasty fumes, not recommended.

In addition I tried some soap mixtures but no avail.

Soda blaster was the most effective experiment. Still I could not remove the paint completely, paint was like melted into the plastic.

Eventually I got tired and accepted my failure. Just good sanding with fine paper and new matt white spray paint was my final solution.

Gasket remover is a caustic soda based thing with strength between oven cleaner and paint stripper in my experience.

I have had some good results using of all things, DOT3 brake fluid.
It takes off the paint but does not harm plastics (in most cases).

Bows head in shame, “I like black retro PCs”

the brake fluid idea may actually work, good idea. Try on a small area.

Sphere478 wrote on 2021-11-14, 21:57:

Bows head in shame, “I like black retro PCs”

the brake fluid idea may actually work, good idea. Try on a small area.

I have nothing against retro computers that are originally black, like the Next, some ibm aptiva, gateway destination, or dark blue like the dells. But I think it's a complete fiasco to paint a classic pc case with paint, even more brilliant paint

To remove paint from metal, it is very easy, since traditional removers, even that technique of removing rust by dipping into a solution of salt water and electrical wires, work very well.

But I've always had bad experiences with plastic, I once tried to remove spray paint from playmobil dolls, and they ended up melting.

I believe spray paint is some kind of fine enamel paint

Used this twice, first time with great success in my attempt to restore the faceplate of an Asus DVD-ROM unit that I painted black in my youth. Few hours in a tray, submerged in the solution, and the paint was all wrinkly and super easy to remove.
Second time I've used it to restore some bits (removable ornaments) of an AT case front panel that someone painted pink. This round it took a couple of days, and the paint still needed some good scraping to remove. The end result was not so good mainly because the painted bits returned to factory-colour whereas the rest of the front panel was badly yellowed.

quicknick wrote on 2021-11-15, 00:08:

Used this twice, first time with great success in my attempt to restore the faceplate of an Asus DVD-ROM unit that I painted black in my youth. Few hours in a tray, submerged in the solution, and the paint was all wrinkly and super easy to remove.
Second time I've used it to restore some bits (removable ornaments) of an AT case front panel that someone painted pink. This round it took a couple of days, and the paint still needed some good scraping to remove. The end result was not so good mainly because the painted bits returned to factory-colour whereas the rest of the front panel was badly yellowed.

Can you tell me which substance is this, so I can try to buy it here in my country?

Really can't help with that, the datasheet only specifies < 5% Non-ionic surfactants. Seen that on a lot of detergents, but they usually don't strip paint from stuff 😀
I used the product a few times without gloves and it wasn't pleasant - it's very alkaline, dunno if this is due to the surfactants or maybe there is some added NaOH , so maybe the paint stripper mentioned above (caustic soda-based) should work too...