Monday, May 17, 2010

Chemistry of your hair: Quick summary about damaged hair

We've established that hair in good condition is easy to comb, easy to manage, and free of fly-aways. What does it mean to have damaged hair? What causes it? And how can we repair it?

Hair can be damaged in a variety of ways - through chemical or mechanical processing, exposure to the sun and weather, and erosion of the cuticle over time. When the hair shaft is changed through these various processes (which I'll be covering over the next few days), generally the fatty acids on your cuticle will start to degrade, which can lead to those shingles on your cuticle lifting up. If this happens, things can penetrate your hair shaft or it can reveal the cortex.

Friction is the enemy of our hair. When a hair strand rubs too much against another hair strand, we see a build of up static electricity, which can lead to fly-aways. We also see the cuticle tiles rising up and interlocking, which can cause the tangles. If our cuticle has eroded too much, the cortex may start to take on water, which will swell the hair and cause it to be thicker, which can lead to more friction! (Almost every form of hair damage will result in increased friction which can lead to more damage! It's a never ending circle of annoyance!)

Friction can take the form of combing forces, meaning the force we put on our hair when we comb or brush it. Wet hair is far more fragile than dry hair. The combing forces are higher and you can do maximum damage trying to get tangles out of wet hair - you can not only lift the cuticle cells from the surface but you can actually tear them away!

Tension isn't a friend to our hair either. When we pull it back in a ponytail, slide a hair straightener or curling iron down it, or put it in cornrows (especially if we are hanging things from it), we create tension. Hair is incredibly strong - the hardness has been likened to stainless steel - with a breaking load of about 100 grams, but if your hair is damaged, that number is definitely lower. For some people, even a ponytail is too much tension!

Changing the chemistry of your hair can lead to damage and further damage. When your hair has been damaged in some way, it becomes more hydrophilic as the fatty acids on the outside are stripped away. This means your hair likes water, and will allow more of it to enter the hair shaft. This sounds like a good idea - water equals moisture and moisture is good - but a swollen hair shaft is doubleplusungood!  It means the hair strand swells so the cuticle is lifted. It can lead to more friction damage and tangles. It also means the good stuff like our cationic quats and silicones won't adsorb to the hair (because they like hydrophobic or lipophilic hair!) and can't work their magic to make our hair feel nicer and more conditioned!

We can't permanently repair the damage we've done to our hair through mechanical or chemical processes, but we can make products that will help to minimize current damage or prevent future damage. We have a few more posts on the state of our hair, then we'll get to some serious formulating!

Here are some great tips from the Beauty Brains on how not to damage your hair! 

Join me tomorrow for more on damaging your hair through chemical processing. 


Topcat said...

Awesome explanation - thanks!

Anonymous said...

how did I miss this post!!!!! Shame on me!!!

Perfect, this answers a previous question I posed on the "what do you wana know post" ..

Love it!

selina.aliens said...

But doesn't panthenol swell the hair shaft?
Or might? I was thinking about adding it to my home made conditioner, but perhaps I should not use it or only put very little?

msjekyll said...

I thought panthenol makes your hair "thicker". But not necessarily how it does that?

Susan Barclay-Nichols said...

Hi msjekyll! Check out the posts on panthenol, like this one, for more information.