I've never used acetone to degrease, but M.S. is a solvent and your skin definitely needs a washing with Dawn/cold water before rinsing and then soaking in clean, cold water. I'm not sure if acetone would also need a Dawn washing or not. I do not know if it is solvent based. Acetone evaporates SO quickly that I would imagine most of it is gone. Personally, I would follow up (after washing) with either DA/Water or the borax solution overnight to help preserve. You're just degreasing if you're going from acetone to water to mounting. Probably doesn't matter much with fish skins anyway as long as you get all the meat out. But, I would rather err on the safe side. I like DA as a final soak before rinsing/soaking in cold water because DA not only acts as a preservative, it also degreases. Just my way of doing things!