By Laura Holton
Alcohol is renowned for drying out hair. Those with curly hair in particular are warned against using products with alcohol, as their hair requires is more prone to drying out. However, the truth is that different types of alcohols have different properties. While some are damaging to the hair, others provide benefits and in fact help the hair to retain moisture.
Those in the group known as short-chain alcohols do dry out hair. This is due to their ability to dissolve oil and remove water. Alcohols in this group include ethanol, SD alcohol, SD alcohol 40, alcohol denat., propanol alcohol and isopropyl. Drying caused by alcohols of this type can cause hair to become frizzy. They are used to ensure products are spread evenly around the hair. In sprays containing these alcohols, drying of the hair can be prevented by spraying eight to ten inches away from the head.
In contrast, fatty alcohols can be beneficial to hair when used appropriately. These usually come from natural sources and include lauryl alcohol, cetyl alcohol, myristyl alcohol, stearyl alcohol, cetearyl alcohol and behenyl alcohol. They act as humectants in products making hair soft and smooth. Found in shampoos and conditioners, alcohols of this type are a cheap alternative to more expensive thickeners.
Other alcohols that do not come into either category are benzyl alcohol and propylene glycol. The first works as a preservative, allowing products to last longer. The latter is an emollient, like the fatty alcohols, and is used to stop hair from becoming dry.