You can only put metal tools in the autoclave, says Choi. And as we stated before, only an autoclave kills a 100 percent of all bacteria and viruses. Nail salon tools like pumice stones, emery boards, nail buffers and foam toe separators need to be swapped out after each use to prevent the spread of bacteria. That's why you're best off bringing your own — just in case the salon doesn't follow this practice. If you see any white residue on a nail file, it means it's been used on someone else.