 
Did you ever notice that when your hair is wet, especially after you've just washed it, you can run your fingers through it and it squeaks?That's where the expression 'squeaky clean' comes from! The question is, why does your hair squeak when it's clean! Let's look at some hairs close up and find out ...  Here's a drawing of a dirty hair. This is the way your hair looks most of the time. The hair shaft is coated with a thin layer of oil from your scalp. This oil helps to protect the hair from damage, and from drying out. Unfortunately, the oil also collects dirt. You can see all sorts of dirt particles embedded in the oily film; these tiny particles come from dust, dirt, pollution, and smoke in the air. The particles make your hair feel 'rough', and the oily surface absorbs the energy from your moving fingers. There's no vibration, and no sound.  Here's a hair that has just been washed, either by having been immersed in water when swimming, or by showering with a detergent shampoo.The dirt is gone, and so is the oil. All that's left is a smooth strand of hair. If you run your fingers through clean hair like this, friction between your fingers and the hair itself will make the hair vibrate just as if you were running your finger down a violin string. That's the squeak! Your hair would dry out and deteriorate if left in this condition. But you don't really need expensive shampoos and conditioners to restore a protective layer of oil to your hair; a quick few strokes with a brush after it's dry will bring more oil from your scalp to cover your hairs once more! And then they won't vibrate. |