There's no problem with acetone and some will even add it, especially with zero nitro fuels. Shell methanol has it as standard at 3%. I'm no expert on nitro but I believe that pure nitro can become shock sensitive which is why a dye is added to show if it's still safe or not. Diluting pure nitro with a tiny amount (maybe 1%?) of methanol stops it becoming shock sensitive. Or so I've read.....