In shaving parlance, hysteresis is that which supposedly makes two blades better than one.

When shaving with a multiple-blade razor, the first blade cuts into the whisker while simultaneously pulling it out slightly. Before it can retract, subsequent blades cut the hair even closer, resulting in whiskers which end up below the surface of the skin.

According to Cecil Adams of The Straight Dope, Gillette claims to have slow-motion microphotography demonstrating hysteresis.


The Gillette Company Web Site:

The Straight Dope: