Well this painted wrap is a excellent test. Being the red paint has been on there for who knows how long. The first test was the soak and in 50-50 mix solvent and H2O. Nothing after 3 hours......yikes. So I dumped it and switched to straight solvent which is slowly working. I'm letting it sit overnight. I also wrapped a piece in a shop towel soaked with solvent and put it in a HD baggie. Before I left work it was slowly coming loose with a little plastic scraper. No ill effects to the wrap either. So I think the best plan of attack on a stubborn shell would be to soak rags/towels in solvent and wrap them around the shell. Then wrap plastic wrap around it to prevent it from drying out. And let it sit 12-24 hrs.
Glenn, I told you that red paint was pretty darn stubborn. I tried lac thinner on it and realized it was going to be too much work. Here is some pics of the drums that these wraps came from.
The pic of the red sparkle kit is the thin wrap with the blackish back.
The lime green kit was the painted red wrap.
The blue floor tom is the, well you know.
I have several pics of the painted red mij drums, if you want to see them before I removed the wraps.