Every few years or so, a beauty myth springs up which has little basis in fact. By now, we've all heard that shampoos containing sulfates are bad for your hair, and in virtually every salon, sulfate-free shampoos are flying off the shelves. But are sulfates really as evil as hairstylists and beauty magazines would have you believe?
Sulfates are surfectants, the magical ingredients which clean the hair, remove styling product and oil buildup, and allow shampoo to lather. There are two primary sulfates used by shampoo manufacturers, sodium lauryl sulfate and sodium laureth sulfate. To the casual observer (and ignorant hairdresser) there doesn't appear to be much a difference between these ingredients; however, there is a world of difference between sodium lauryl sulfate and sodium laureth sulfate, as anyone with a degree in organic chemistry will tell you. Just because words sound the same, it doesn't mean they are the same- otherwise, we'd be putting bandanas in our fruit salad and tying bananas around our necks.
When it comes to hair, sodium lauryl sulfate is the "bad" sulfate which you should avoid, not because it damages the hair, but because it can strip away artificial hair color. This is because sodium lauryl sulfate is a very small molecule and can easily penetrate the hair's cuticle. Since color molecules from hair dye are trapped in the cortex (the layer of the hair beneath the cuticle), these pesky sulfate molecules can get inside, resulting in premature color fading.
Not all sulfates have tiny sized molecules, however. If a sulfate molecule is large, it cannot penetrate the cuticle of the hair, so it will not strip away color (the molecules will simply "bounce" off the surface of the hair). Myreth sulfate for example, is a very mild surfectant and is perfectly safe to use on color-treated hair.
Now that you know the truth behind sulfates, you can prevent uninformed beauty experts and hairdressers from talking you into purchasing over-priced haircare products that lather poorly and are ineffective at cleaning your hair.