Boiling is what most people do but then there are others that don't. They just use it right out of the box or bag. Any sterile cotton should be just fine. I've heard of people using the cotton from Q-tips. I almost bought a bag of cotton balls just recently and it said "sterile" but it had 2 chemicals in it, peroxide and something else so I put it back on the shelf. Boiling should remove any chemicals but since I don't use cotton balls (yet) I can't say for sure. I've used cotton rope and boiled it before using. Even after boiling it still has that funky taste for awhile but then it's pretty good. Too bad it burns so fast.