Sodium lauryl sulfate is an incredibly common ingredient in hair and skin care products. The ingredient is FDA-approved, but has come under fire in recent years, leading some skin and hair care companies to discontinue the use of ingredient in their products. The ingredient has a number of alternate names, which can make it difficult for consumers to spot the chemical on ingredient lists in products. Among these other names are SLS, sodium dodecyl sulfate, SDS, docetyl sulfate sodium salt, sodium lauryl sulfate ether and sulfuric acid monododecyl ester sodium salt.
Although sodium lauryl sulfate is an organic compound, it is industrially manufactured for use in hair and skin care products. To produce the ingredient, manufacturers begin by extracting lauryl alcohol from either palm oil or coconut oil. Then, the lauryl alcohol is combined with sulfur trioxide gas, a substance that is derived from a very strong acid known as sulfuric acid. The resulting substance is very acidic in nature and would cause damage to the skin if applied in its raw form, making it necessary to add sodium hydroxide or sodium carbonate to neutralize the chemical, creating the finished product--sodium lauryl sulfate. In its raw form, sodium lauryl sulfate is either a fine, white powder or a tablet or pellet formed from this powder.
Sodium lauryl sulfate's primary role in hair and skin care products is that of a surfactant, an ingredient that is vital to products designed to cleanse the skin or hair, such as shampoos, facial cleansers, body washes, shower gels and soaps. The purpose of cleansing products is to remove oil and impurities from the hair and skin to keep them clean and healthy. The reason that shampoos and cleansers are necessary is that ordinarily, water does not mix with oily substances and instead, forms beads and rolls off.
The mechanism behind this phenomenon is a force known as surface tension, which helps liquids etain the shape of their droplets. Water has a lower surface tension than oily substances, and is therefore unable to disrupt the shape of their droplets to combine with them. When a surfactant like sodium lauryl sulfate is added to water, the ingredient lowers the surface tension of oils and dirt, allowing the water to mix with the substances and then wash them away.
As a surfactant, sodium lauryl sulfate is very effective and capable of cleansing even very oily hair or skin. The ingredient also produces a large amount of foam and suds, which many consumers prefer. The industrial manufacturing process used to create the ingredient is rather inexpensive, which is one of the main reasons for the popularity of the use of sodium lauryl sulfate in the hair and skin care industry. By using the ingredient in their formulas, manufacturers can cut down on costs and, in turn, offer products at a cheaper price. For those looking for an inexpensive hair or skin care product, one that contains sodium lauryl sulfate offers maximum effectiveness at a more affordable price than many products that contain alternative ingredients.
One of the drawbacks to sodium lauryl sulfate is that the ingredient is a known irritant. In people with sensitive skin or skin allergies, sodium lauryl sulfate has the potential to cause redness, irritation and swelling. Studies have found that sodium lauryl sulfate is most likely to cause irritation when left on the skin for an hour or longer, and as a result, it is important to thoroughly rinse the skin or hair after using a product that contains the ingredient to ensure that none of the chemical remains on the skin or scalp.
Another concern regarding sodium lauryl suflate emerged after studies found that the ingredient may have a detrimental effect upon the hair. In one such study published in the International Journal of Cosmetic Science, samples of hair that were exposed to sodium lauryl suflate were studied under a microscope and found to have developed structural flaws in the protective coating of the hair strand, known as the cuticle. In theory, if sodium lauryl suflate is able to damage the cuticle, the ingredient could make the hair more susceptible to split ends and breakage; however, more research is needed to determine the likelihood that sodium lauryl suflate could produce this much damage to the hair.