After shaving, most people want silky smooth, clean-looking skin. They don't want skin dotted with nicks, razor burn or ingrown hairs.
For a close shave (which will also be smooth and long-lasting), you need only to cut the hair below the skin's surface. This isn't violent. The razor doesn't dig into the skin. Rather, many multiblade razors use this technique to shave closer than a single blade. Here's how: The first blade is blunt. It hooks the hair above the surface. As you push the razor, the blade pulls the hair forward and up. The next blade is sharp, and it comes behind and slices the hair. The hair finally retracts into the follicle, below the surface.
One researcher focused a video microscope on men's jawlines to compare how closely an electric razor and a two-blade safety razor shaved men's beards. The electric razor tore the hair above the surface. The safety razor cut the hair below the surface [source: Draelos 2002].
Continuing this logic, Gillette claims that five blades cut closer than two do. It's because the catching-and-cutting process repeats twice: The first blade catches, the next cuts, the third catches and the fourth cuts. (We're not sure what the fifth blade does.) After this multi-pronged attack, the hair retracts even farther [source: Burns].
Some old-school barbers say straight razors give the closest shave. By their logic, you can vary the razor's angle to meet every hair, even in wild patches, something you can't do with a safety razor [source: Kugel]. Of course, you can nearly Sweeney Todd yourself if you don't learn proper technique.
If more blades make you worry about nicks, you're not alone. Some dermatologists recommend no more than two blades to avoid nicks. When razor heads occupy more area on sharp curves, the razor is harder to control. If the blade can't match the surface, you'll nick yourself [source: Burns].
Nicks also happen when the razor pushes down on the fat under your skin, forcing your skin into a hill in front of the razor. If the blade is the first thing the hill encounters, you get nicked. Safer razors place a flat surface in front of the blade to flatten the hill. Gillette says it tackles the hill problem by distributing the downward force over five closely spaced blades [source: Burns]. The simplest way to avoid nicks, though, is to shave gently instead of bearing down.
Nicks probably aren't the only shaving hazard you have to face. Learn how to deal with those pesky ingrown hairs next.