I'm restoring a 1956 Cessna 172. I've finished repairing things mechanical, and redid the interior and now I'm into stripping the paint. So far I've used several paint strippers and found Dad's in the green can to be very effective in removing the top 5 layers of paint. However, the original layer of paint, a dark blue, is very tenacious and nothing I've tried seems to soften this paint. Can anyone suggest a stripper that will take this off and get me down to bare aluminum? Also need to know where I can get some of it.