AARRRGH! Painted Plexi crinkled!

[TOK]

Has anyone had to strip paint from Lexan/Plexi without damaging the surface?

Here is the long version of my horrible tale!
Building my second control panel, and instead of covering the wood under the plastic, I decided to paint the underside of the Lexan (acutally Makrolon brand) black. My first inclination was to use paint made for R/C car bodies (for anyone that doesn't know, it's a flat color and you spray it on the underside, the plastic gives the shine).

I felt like working on it, and had some regular (Rustoleum) spray on hand. As a test, I used a spare piece of Makrolon and sprayed it with the Rustoleum and let it sit overnight. It came out gorgeous! The black on the backside of the quarter inch plastic gave it a very deep and glossy sheen. Convinced the stuff I had would be OK, I abandoned the idea of the R/C car body paint and painted my panel. It looked great, but when I got up the next morning, I found a few spots had crinkled up. I was horrified, but I cleaned them up as best I could and sprayed them again with the same result... Actually worse, since apparently the new coat of paint (or its propellant) attacked the finish that was OK.
It's now a disaster.

I'm faced with having to strip this panel before using the correct plastic paint, but I'm not sure what to use to safely strip it without fogging the Makrolon or making it brittle. I tried wiping it with rubbing alcohol, which seems to help soften the paint a little, but its still a lot of work. I'm considering pressure-washing it. Has anyone else been through this mess? Cutting another plastic panel would be a bit of a pain since my control panel isn't square, and I already had all the holes for the sticks, buttons and trackball/mount done. I'd like to salvage this panel without spending four days stripping it!
 

[RayB]

I may be wrong here, so wait for a second opinion, but my guess is you need to sand the surface before painting it. Might sound like the wrong thing to do, but if you think about it, like you said, the top of the plexi is providing the sheen, so in theory it should work out.

~Ray B.

[paigeoliver]

You might just have the wrong combination of plastic and paint. I have painted a lot of plexi and never had that problem.

[TOK]

Ray B: You can't sand the plexi, because it will show. You're sanding the bottom then painting it, then looking through from the top. You'd see the sand marks before you saw the paint.

My problem is definitely what Paige alluded to, that the paint just isn't sticking to the plexi. I got a small can of the R/C car paint and tested that. It seemed to work well. I wiped it off afterward, and notice that it actually does a slight etching of the surface as it dries, I guess that is what helps it stick so well.

What I need to do now is figure out what I can use to strip the paint. The paint isn't sticking well, but it is sticking, so it's not going to be easy. Anyone know of a gentle solvent that won't harm or discolor the plastic but will still loosen the paint?
I tried some WD-40, my thought being that the propellant in the can, and not the WD itself might crinkle the paint, but it had no effect.

[paigeoliver]

Do it over, you know it is never going to come out correctly now.

[SOAPboy]

grab some of that uber strong spray paint thinner stuff.. strip it, repaint..

should be just fine..

[RayB]

How much does paint thinner cost VS the cost of a new plexi?

[Witchboard]

I would think the thinner would melt the plexi, or at least frost it where ever it touches.  Sounds like to me the reason your paint crinkled is because your plexi wasn't clean in those areas, or there was some type of residue.

[TOK]

I pressure-washed it this afternoon, and got the paint off rather easily without marring the plastic.

The downside is that I made some other marks where I tested the R/C car paint, etc, so I think I'm going to take Paiges advice and create a new panel.

Should go pretty quick using the old one as a blank. I have enough for another panel, but I was hoping to use that remaining piece to cover the panel on a bartop machine in the future. A buddy picked it up for me from work, I don't want to be a pest and I'm not sure how much he can get. As far as chemical strippers, I think Witchboard is correct about paint thinner being too harsh. I've seen solvents either yellow plastic, frost it like he said, or make it very brittle. I also agree that something may have been on the surface. I was stupid not to wipe it down. I pulled off the protective plastic, made the dumb assumption that it must be clean under there, and now I'm wasting a lot of time!

Dumb!  

[TOK]

After taking Paiges advice and creating a new plexi overlay, I decided to experiment a little bit with the one I screwed up. I used 220 grit paper in an orbital sander and sanded the whole thing, giving it a "frosted" look.
I doubt I'll ever use it, but it did look pretty cool over the black wood. Tomorrow I might just paint it from the bottom when I paint the new piece just to see how it looks. My buddy commented that the frosted version might look cool lit from underneath.
I'm more into traditional cabs, but just wondered if anyone did anything with sanded plexi?

Here is the new panel I cut with the protective covering still on it, and the one I screwed up and sanded. Sorry it's a little smudged up. I wasn't exactly careful with it after I screwed it up!