A single thin, sharp, perfectly designed blade is a great start. But to get a really close shave, you need more than one.
Why is a 3-blade razor, such as the Gillette Mach3, cutting closer than a single blade? And why are 5-blade razors, like the Gillette Fusion5 ProGlide, still cutting closer than MACH3?
To understand why more blades can help you get a closer shave, you have to first understand the way
that the skin on your face and the hairs growing from it behave.