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Thread: Effects acids and bases/alkalis have on hair.

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    Member bjjowett1993's Avatar
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    Default Effects acids and bases/alkalis have on hair.

    Let's start off with the science behind this.

    The pH scale (Power of Hydrogen) goes from 0-14, 7 being neutral, (Pure water) and anything lower is acidic, anything higher is alkali/basic. What the numbers indicate on the scale is, if it is a 0, such as hydrochloric acid, it means that the substance has very low amounts of Hydrogen bonds within its molecular structure. Whereas 14, such as lye, has very high amounts. Hair and skin has a pH level of about 4.5-5.5, making it slightly acidic, whereas our bodily fluid, with the exception of stomach acids, should be alkali/basic.

    So when a weak acid, such as vinegar (pH of 2.4 - 3.4{chemical name: acetic acid}) is applied to the hair, closes the cuticle, making it softer, and shinier. Acid rinses are also good for returning the hair to its natural shape, so for instance, if you set your hair in really tight curls or ringlets, (or if you heat style, crimping) and even after having a shower, there is still a little wave, when your hair is usually stick straight, this will help return your hair back to normal.

    Now on the other hand when alkali/basic substances are applied to the hair, it has sort of the opposite effect. It opens the cuticle, making it look dull, and feel rough. Alkalis/bases are used in such products as dyes/bleaches, to make it easier for colour to be removed, or put into the medulla and cortex of the hair shaft. Alkalis/bases are also present in relaxers and perm solutions, which leads me to my next point about alkalis/bases.

    A strong alkali/base such as lye (Sodium Hydroxide), has a pH of 14 and what strong bases/alkalis do to the hair other than what I have already said is, if the hair is curly, for example. a base/alkali will straighten the hair a bit. So if your shampoo is basic/alkali, then some curl will be lost unless you switch your shampoo, or do an acid rinse. Perms, are essentially the same thing as relaxer, chemically speaking anyways, obviously not cosmetically. The only difference between a perm and a relaxer, is the shape you are trying to get the hair to conform to. For perms, you roll the hair, then apply the perm solution, where as relaxers, you brush it back, and then apply the relaxer, thus straightening the hair.

    Other ways of closing the cuticle are: using a final cold water rinse, or cold water throughout, and using soft water, ideally "pure" rain water. Ironically, "pure" rain water, (before we started screwing over our environment) was slightly acidic, having a pH of 5.5, which would benefit hair and skin, and is naturally the softest water, in terms of minerals present within the water. If we showered with cold, pure rain water, and our hair was virgin, and we did eveything else hair-concious people should be doing, our hair would be absolutely breathtaking!

    ETA: Also, I've read questions of whether or not acids will dry out your hair. If your hair is damaged, from moderate to extensive damage, it will dry out your hair a bit, but this effect can be counteracted by diluting the acid a fair bit. Acids are also good for clarifying hair of some types of build-up, such as soap scum, etc. but not build-up from hair products, such as silicone. Also helps relieve dandruff.
    Last edited by bjjowett1993; March 10th, 2009 at 06:45 PM. Reason: Sentence and paragraph structure. Accurate information.

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