I’ve been working on prepping the plastic body panels for paint and have, like may of you, run into the problem of removing the thick top layer of clear that sits on the paint. I’ve tried sanding, chipping and finally heating it, so here’s what I found to be the easiest solution.
Someone here has suggested a heat gun and a putty knife. This is the correct and easiest way to remove the paint, however heating and scraping at the same time is not the correct method.
The clear needs to be heated to the point it is bubbling and turns from a clear to a cloudy and milky layer and then some more. This requires a good deal of heating; it will begin to melt. It will bubble. EDIT- Bubble slightly, no larger than when water is just about to boil. You don’t want big bubbles. This is where you want it to be. Do not scrape it at this point; keep going until all of the clear you want to remove in that section has been heated to the same consistency. If you try and remove it while hot it can and will turn into a gooey mess that will just require a lot more work later, plus you’ll end up digging into the paint and plastic below. Let it cool until you can touch it, then break out the putty knife and rubber mallet and start chipping away. The heat will have released the bond between the clear and the paint, making this job a lot easier (if not possible).
A few warnings. Be sure that when heating any part of the panel that it is not stressed in the position where it sits as this can cause the panel to bend with heat. Be careful around any holes; they can deform. Same goes for crevices. They can warp (although it’s not hard to repair with additional heat). Wear goggles! I had not had any of the bubbling clear coat pop or splatter, but it could happen, and when you begin chipping little (sharp) shards of plastic will go flying en every direction. You should probably wear a respirator as well; who knows what kind of chemicals are released with the heat.
Hope this helps.