A Moment of Science

A Close Shave

Is shaving cream really necessary, and if so, how does it work? Learn more on this Moment of Science.

Man shaving his face

Photo: The Newb (flickr)

Using shaving cream helps to completely saturate hair, making it an easier and more efficient shave

In theory, shaving ought to be simple, the razor cuts the hair.

In practice, it’s not just a matter of razors and hair, there’s also shaving cream to consider. Is shaving cream really necessary, and if so, how does it work?

While there’s a wide variety of shaving foams available, some with perfumes or other chemicals for your skin, they’re all wet, and this wetness is the key to their function.

Wet hair is much easier for a razor to cut than dry hair is, because water makes the proteins in your hair soften and expand. While it’s possible to shave with a completely dry razor, you probably don’t want to try it–it’s both painful and inefficient.

The best way to use shaving cream is to apply it, then wait a couple minutes before shaving. This is because, while wet hair is good for shaving, completely saturated hair is even better. It takes about two minutes for the hairs to soak all the way through. This is a good reason to use shaving cream, instead of just wetting your face with water. The foaminess of the cream helps hold the water in place long enough to soak in.

For an electric razor, of course, you shouldn’t use shaving cream. Electric razors shear your hairs off, snipping them like tiny scissors. This works best on brittle hair that’s pointing straight out, which is why electric shaving lotions contain alcohol to dry the hairs and make them stand straight.

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