On Fri, 12 Oct 2012 21:40:36 -0700 (PDT),
wrote:


he uses a cotton swab and dips it in a pint bottle of pure acetone and then uses the swab to blot out the stamped number.

I know nothing about pure acetone other that I read it is
flammable. my roomate just told me it was fingernail polish remover (which women use all the time in the house) so it should be no big deal to use in the house.

All correct. A little on a swab is probably not going to do anything
at all. At a minimum though, I'd have a window open. To avoid
spills, go outside and pour off some into a small container of a few
ounces instead of the quart or gallon he is now using. Be careful
where you store it too.

If you have a pilot light on a heater, be sure to stay far away from
it, don't smoke, etc. Open two windows and have a fan blowing in one
to force the air out the other. Remember, it is the fumes that are
dangerous.