时差N小时 怎样把胡子刮干净（在线收听）

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

理论上说，刮胡子应该很简单：剃须刀切断胡须。

In practice, it's not just a matter of razors and hair, there's also shaving cream to consider—foamy stuff that you smear around your hairs before shaving.

实际上，这并不只关系到剃刀和胡须，也要考虑能产生泡沫的剃须膏，在刮胡子之前把它涂抹在胡须周围。

How come? Is shaving cream really necessary and, if so, how does it work?

为甚么？剃须膏真的有必要吗？如果有，它是如何作用的？

While there's a wide variety of shaving foams available, some with perfumes or other chemicals for your skin,

尽管市面上有琳琅满目的剃须膏可供选择，一些带有香水，一些带有护理肌肤的其它化学成分，

there's one thing that they all have in common: They're all wet, and this wetness is the key to their function.

但是这些剃须膏有一个相同点——湿润，这正是它们发挥功效的关键。

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.

刮湿润的胡须通常要比刮干燥的胡须容易，因为湿度使胡须内的蛋白质软化扩张。

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.

虽然也可以用干燥的剃须刀刮胡子，但你可能不会去试，因为这样既疼痛又效率不高。

The best way to use shaving cream is to apply it, then wait a couple minutes before shaving.

使用剃须膏最好的方式就是将其敷在胡须上，等两分钟再刮。

This is because, while wet hair is good for shaving, completely saturated hair is even better.

这是因为除掉湿润的胡须很容易，那么除掉湿透的胡须则更容易了。

It takes about two minutes for the hairs to soak all the way through.

只需两分钟，水分就可以完全浸透胡须。

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.

剃须膏产生的泡沫会长时锁住水分，使其浸透胡须。这就是为甚么要用剃须膏，而不是直接用水打湿胡须的原因。

For an electric razor, of course, you shouldn't use shaving cream. Electric razors shear your hairs off, snipping them like tiny scissors.

当然用电动剃须刀剃须的话，就不应该再用剃须膏了。电动剃须刀像小剪刀似的将胡须剪掉切碎。

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.

它适用于脆性易断，直立向外生长的胡须，这就是为什么电动剃须香液里含有酒精——酒精使胡须干燥，并直立起来。