The older vintage instruments used nitrocellulose lacquers that are easily removed using boiling water with a bit of baking powder added. The epoxy lacquers on newer instruments, including the notorious Yamaha hard to remove lacquers can be removed using Klean-Strip Aircraft Paint Remover. I prefer the spray which I use outdoors when the weather is above 60 degrees. It is water soluble and easily rinses off with garden hose.