Got gel manicure today and they was able to take off the previous gel off really quickly with putting acetone in this machine that is warming. After that the male nail tech put the used acetone back in the bottle. Now I can assume that he will sanitize the machine and the bottle that he put the used acetone because they do refill the bottle with acetone remover.But how can I be sure.. Gross!!! On a positive note my nails did look good!