Men have been using razors to shave for thousands of years, constantly nicking themselves every morning. So why haven't they ever started using depilatories? After all, they seem quite effective and easy to use. They come in the form of a cream or a lotion that you spread on areas with unwanted hair. You leave the stuff on for a few minutes, and the hair comes right off.

This is because hair is made primarily of what is known as keratin, a very hard protein that is also found in fingernails and in the horns of animals. The way depilatories work is that they contain a chemical that softens and loosens the fibers of keratin. In other words, depilatories dissolve the protein structure of the hair, causing it to separate from the skin surface.

The problem is that hair is a lot tougher than skin. So the same chemicals that destroy the hair can also cause serious skin irritation--and possibly even chemical burns--if left on too long. Also, depilatories are more effective when used on fine hair rather than on coarse hair. And men's facial hair tends to be really tough.