Thursday, October 27, 2011

Your Hair on Chlorine

First of all, you need to know that your hair’s cuticle – the layer of protein “scales” which form its outermost layer have an additional covering called the epicuticle, composed of protein and fatty acids. An additional layer of protection.©Science-y Hair Blog 2013

Chlorine in water from your tap or in swimming pools diffuses through the cuticle of your hair. This causes hair proteins to break down beneath the epicuticle, but these proteins are too large to move out of the epicuticle – so frilly bubbles appear as the inward moving water and chlorine swell the hair and the degraded proteins cannot escape, despite the pressure caused by the swelling. This is difficult create when you want to photograph it! I have seen it before and I have a great picture which I cannot reproduce because it is in a copyrighted text.©Science-y Hair Blog 2013

Chlorine in your water or swimming pool breaks down your hair’s protective outer layers. This robs the hair of its ability to hold water (stay hydrated) and also strips away oils and fatty acids. In short, chlorine makes your hair more porous, dry and weaker.©Science-y Hair Blog 2013

For a highly chlorinated home water supply, there are filters you can put on your shower which remove chlorine (your skin will like this too). The filter cartridges must be replaced 2-3 times per year and will not alter water hardness, but can remove some metals and some undesirable chemicals.
©Science-y Hair Blog 2013
When you are swimming, wear a swim cap. But only to keep your hair from tangling and to keep hair out of the pool’s drain. Swim caps do not keep water out!
©Science-y Hair Blog 2013
Recipe: Chlorine Odor Remover
To remove chlorine odor and metals which could cause discoloration from your hair, mix a scant 1/8 teaspoon of citric acid with 2 cups water (about 0.5-1 ml citric acid crystals or powder in 500 ml water). If your hair is long or very thick, double this recipe. Rinse your hair very well after swimming (shampooing is not necessary) – for at least 1-2 minutes. Then apply the citric acid rinse and leave it on for at least one minute. Then rinse and apply conditioner. Why would metals be in pool water? As a part of fungicides used to keep the pool fungus-free, or as a part of the local water in general. Copper (from fungicides) and iron are especially discoloring to hair.©Science-y Hair Blog 2013

The Tests:
To keep chlorinated water from contacting your hair, you need to apply a protectant. I tested several and microscopic photographs will follow. I used no treatment (control), coconut oil, olive oil, conditioner with oils and silicones, and conditioner without oils or silicones. I rubbed these on dry hair and made sure the hairs were thoroughly coated. Then I placed the hairs on slides in water with enough bleach added to simulate swimming pool water. I erred on the side of too much. Swimming pools are also buffered to moderate their pH and I did not do that with the solution I made up, the pH was too high for hair. So when you see the untreated hairs below, don't panic - it's probably not that bad where you swim.©Science-y Hair Blog 2013

At the outset, the untreated hair showed some lifting of cuticle scales and bubbles on the surface. The oil and conditioner samples were all coated with their respective treatments and protected from the water.©Science-y Hair Blog 2013

The Results:
After 20 minutes:
-Untreated hair: Further lifting of cuticle scales
-Oil treated hair (both oils): oil coating remains, perhaps less robust, some water seems to be finding its way to the hair in the olive oil treatment.
-Conditioner treated hair (both with and without oils and silicones): Hair is still surrounded by conditioner, no water appears to be penetrating the conditioner coating.
©Science-y Hair Blog 2013

After 30 minutes:
-Coconut oil treated hair: Coconut oil coating is intact and repelling water
-Olive oil treated hair: Large bubbles are appearing in the oil coating – water has penetrated the oil barrier.
-Conditioner treated hair (with and without silicones): Conditioner barrier is intact and repelling water.

Untreated hair, start

Untreated hair at 20 minutes

Untreated hair at 30 minutes

Coconut oil, start

Coconut oil at 20 minutes

Coconut oil at 30 minutes

Olive oil, start

Olive oil at 20 minutes
©Science-y Hair Blog 2013
Olive oil at 30 minutes - small and large bubbles due to water penetrating the oil barrier
I believe the bubbles close to the hair are the moisture and proteins from the cuticle, pushing the
epicuticle outwards...
©Science-y Hair Blog 2013
Conditioner with oils and silicones, start
©Science-y Hair Blog 2013
Conditioner with oils and silicones, 20 minutes
©Science-y Hair Blog 2013
Conditioner with oils and silicones, 30 minutes
©Science-y Hair Blog 2013
Conditioner without oils and silicones, start

Conditioner without oils and silicones, 20 minutes
©Science-y Hair Blog 2013
Conditioner without oils and silicones, 30 minutes

Conclusion:©Science-y Hair Blog 2013
Conditioner applied to dry hair (or wet if you prefer, I did not test this) seems to be good protection for hair against heavily chlorinated water. I suspect this is because conditioner is a wetting agent, so it is not repelled by hair as the oil was, and also because conditioner bonds to hair. Coconut oil either ties with conditioner, or is a close second place.

Note that if your hair is quite porous (damaged, bleached, chemically relaxed or permed) oil, especially coconut oil, will penetrate the hair better than for the hair used in this test, which has no chemical treatment.©Science-y Hair Blog 2013

Also note that this test was done with hair held on slides in chlorinated water without movement. When you are swimming, there will be some movement of water under your swim cap. But the swim cap will keep more of whatever treatment you use in place to protect your hair.

Another note: Conditioners and oils tend to make your swim cap slip off – you’ve been warned.

Managers of swimming pools want to have as few chemicals (lotions, oils, conditioners) added to their pools as possible because maintaining swimming pools is expensive and can be difficult. Use as little oil or conditioner as you need to protect your hair. Respect the rules of the facility you use for swimming as best as possible while taking care of your hair. I have never used any treatments on my hair while swimming because I'd been advised not to for the sake of the pool's maintenance. 

Take-home message: In this test, the best protectant against chlorinated water was conditioner applied to dry hair. Coconut oil was very effective, but olive oil was no longer repelling water by 20-30 minutes.©Science-y Hair Blog 2013

If you want to use these to keep the chlorinated water out of your hair, make sure you have thoroughly coated all your hair with conditioner or oil. Leave no strands behind! Comb your treatment through your hair with your fingers, pat and press it into your hair. Dab off any excess with a towel. Then put on your swim cap and get swimming. (Or at least put your hair in a bun or braid/plait to reduce tangles and hair in the pool's drain).

After swimming, rinse your hair well with water, shampoo out oils or conditioner if you need to. Use a citric acid rinse if your hair picks up chlorine odor (recipe above).
©Science-y Hair Blog 2013
There are swimmer’s shampoos and swimming protectant creams, but I wouldn’t waste money on them. Swimmer’s shampoos do not deodorize the hair as well as a citric acid rinse in my experience, and tend to be very drying to hair. I used inexpensive conditioners for this test and they worked nicely.

If you cannot use protectants on your hair because of pool rules, then rinse your hair well after swimming and use plenty of conditioner, consider using a conditioner with protein if your hair tolerates it.©Science-y Hair Blog 2013

Conditioners used: AG Hair Cosmetics Colour Care Sterling Silver and Suave Naturals Juicy Green Apple

Source: Chemical and Physical Behavior of Human Hair 
Robbins, 1994. 3rd Ed. Springer-Verlag, New York


  1. There is a oft-repeated advice to soak your hair in water before getting in the pool. This is supposed to "fill the hair up" with water, preventing chlorine from getting in the hair. What are your thoughts on this?

  2. I honestly don't know. Chlorinated water attacks the hair from the outside. Even if you wet your hair initially in less-chlorinated (tap) water - it will ultimately be in contact with more chlorinated water - even if you wear a swim cap. WS