Tuesday, May 18, 2010
Chemistry of your hair: Chemical processing
When we subject our hair to perms, straightening, or colouring, we'll see some damage to our hair. All chemical processing leads to chemical changes in our hair, which can lead to an increase in friction (which leads to an increase in friction damage) and an increase in the damage caused by combing forces, leaving our hair feeling rough and dry. Chemically processed hair is affected more by grooming damage than virgin hair, meaning there's more impact on your hair when you dry, straighten, or curl it, and it can even break off at the weak points.
Processed hair tends to be more hydrophilic than virgin hair, so it wants to attract water. This is normally a good thing - water equals moisture - but this can lead to the cuticles lifting, which causes more mechanical damage. We know conditioning is a huge part of keeping our hair in good condition, but when our hair is hydrophilic our lovely oils, silicones, and conditioning agents aren't attracted to our hair and won't stay there as they're looking for a hydrophobic surface. So we need to increase amount of conditioner we use and change some of those ingredients to include more hydrophilic or water soluble ingredients like hydrolyzed proteins and panthenol. (Which is why damaged hair likes intense conditioners - more conditioning agents means more is likely to adsorb to your hair strand.)
Even temporary dyes can have an impact on the good condition of our hair. Some longer lasting temporary dyes - up to 20 washings - can contain some oxidative dyes that can change the disulphide bonds in our hair strands! (And don't get me started on the Just for Men kind of dyes containing lead salts). And don't think henna is the answer! Any dye that coats your hair can increase the surface friction between strands, which we know can cause mechanical damage. (You can tell there's an increase in the diameter of your hair because it feels fuller...this is not a good thing because it increases friction!)
And don't forget the effects of Mr. Sun. UV damage is a type of chemical damage to your hair. It oxidizes the cystine in your hair to cystine S-sulfonate and cysteic acid, which makes our hair more hydrophilic.
So what can you do? Condition, condition, condition. Chemically processed hair really wants those lovely cationic quats and fatty acids. Use a good conditioner with a leave in conditioner, even for very fine hair. And don't forget the benefits of the silicones - studies have shown dimethicone can reduce combing forces (reduced mechanical friction) and form a seal on your hair to repel the water.