Just an FYI......... This is something I tried with great success when I was removing varnish from the interior of my restoration project. I tried a heat gun and basic Zip Strip with limited success. It seemed to take a lot of time and several coats to make any significant progress. A local furniture refinisher recommended I try either Airplane of Marine grade stripper. I purchased JASCO Premium Paint and Varnish Remover (Marine grade). That worked better. However, it still was taking longer than I thought it should. Guess I need to learn patience. So I took an old double boiler, filled the bottom pot with water and brought the temp near to boiling.At this point I took the heated water outside not really knowing what may happen. I poured some stripper into the upper pot and let the heat warm the solvent. The solvent reacted quickly to the heat. Once it settled down I brushed a coat on. The heat did the trick. The stripper dissolved the varnish quickly and made it a lot easier getting varnish out of the nooks and crannies. It took about 4 hours to complete the job. A few words of caution..... even though the stripper fresh out of the can didn't have a lot of flumes, the heat really increases the odor. So do this outdoors, wear glasses, work clothes, and a good pair of gloves. Latex gloves will not protect your skin. Good luck.