Ingredient Technology – Alcohols and Hair

Alcohols by definition maybe defined as a compound that has a hydroxyl group attached to a carbon atom. By large alcohols are used in many industries and have a number of different uses.  In the beauty and cosmetic industry, alcohols may be used as a solvent or as an emollient.    Alcohols fall under two categories – short chain and long chain alcohols.

Short chain alcohols are typically composed of fewer carbons (less than 3 carbons) in the tail.   Because of the structure of these alcohols, they are flammable, volatile and quickly dissipate (evaporate).   Typical short chain alcohols used in hair products are ethanol, SD alcohol, SD alcohol 40, Isopropyl alcohol, Propyl alcohol, and Alcohol Denat.

Longer chain alcohols are composed of many carbon atoms.   The difference in the molecular composition of some selected short and long chain alcohols are reported in Tables 1 and 2.

Table 1. Selected short chain alcohols

Table 2. Selected long chain (fatty) alcohols

Alcohols and Hair

Are alcohols really drying to the hair?   Short chain alcohols are typically more drying to the hair.   This is largely in due to their small structural composition, allowing them to behave more as a solvent.  Because they are solvents, they dissipate easily when applied to the hair and once they dissipate, the hair is left dry with no moisture.   Table 3 is gives some examples of hair products containing alcohols which dry the hair out.  These types of products are generally styling sprays and spritzs.

Table 3. Selected Hair Products Containing Short-Chain Alcohols

Many hair products contain longer chain alcohols that aid in conditioning the hair.  Longer chain alcohols are called fatty alcohols because their consistency is generally a cream like emollient, which aid in conditioning and softening the hair. Table 4. gives an example of long-chain alcohols found in different hair products. They are generally in conditioners, moisturizers and leave-ins.

Table 4. Selected Hair Products Containing Long-Chain Alcohols

So, not all alcohols are equal and their application in hair products depends on their structural make-up. If you are looking for a product that will soothe and soften the hair, try out some of the many products containing long chain alcohols.