This other entanglement is more easily understood. Why does hair tangle and how do you get it untangled?
When you look at hair under a microscope, you can see that the core of the hair is covered with cuticles. Think of them as being like the scales of a fish. Both the cuticles and the core of the hair are made up of keratin – helix-shaped protein molecules. The cuticles are covered with sebum, an oily substance which protects the hair from drying out.
Because hairs are not smooth, if two meet at the right (wrong?) angle, they can snag on each other. If hair is damaged, cuticles may be missing, torn, or more protruding, and the tangling will be worse. Not all hair is the same, of course. Hair ranges from fine to coarse in thickness, and from straight to curly. It’s not a simple problem to figure out what hair will tangle more. A head of hundreds of thousands of strands colliding in all directions is just the sort of knotty problem that mathematicians and physicists love to tackle. Some fine work done by Jean-Baptiste Masson, a brain imaging researcher at the École Polytechnique in France showed that, although curly hairs cross more often than straight, the angle at which the hairs meet is most important. Counter-intuitively, straight hair tangles more than curly. And what appears to be the most important factor is the diameter of the strands. Fine hair tangles more than coarse hair.
How to Untangle Hair
Less surprising than the study of what hair tangles most, is the result of work done by a team of scientists at Harvard. They found — drum roll, please — that untangling hair is best done by starting to comb close to the ends and then working your way up to the scalp.
You can also get some help from the magic of chemistry. There are dozens of commercial Detangling Sprays available. My favourite — based solely on the name — is this one:
The name is based on the widespread myth in Southern Africa that elephants eat the fermented fruit of the Marula tree, get drunk on the alcohol, and rampage around, causing widespread destruction. And of course, what could be more effective at detangling your hair than a rampaging drunken elephant?
The active ingredients in detangling sprays are
- Oils. These replace missing sebum, making hair softer and less likely to tangle.
- Silicone. A substance with long molecular chains that bind to the surface of the hair and make it glossy, smooth and less likely to tangle.
- Acidifiers. Lowering the pH of the hair strengthens the hydrogen bonds between keratin molecules. This smooths and tightens the surface cuticles on each strand.
- Hydrolyzed Protein. Amino acids which are the building blocks of proteins. These help to repair damaged keratin, smoothing broken edges of the cuticles.
- Surfactants. These molecules have one part which binds to the exposed keratin, between damaged cuticles; the other end of the molecule is hydrophobic (repelling water) and creating a smooth thin film that’s easier to comb.
Shampoos are detergents which do one simple job: remove dirt from hair. The dirt is caught up in the oily sebum and the detergent washes it away. Detergents are molecules with one end which is attracted to oil and the other end attracted to water. So one end binds to the dirty, oily sebum and rinsing with water washes away that dirty oil. Any detergent would effectively wash away the dirt. Soap, which is also a detergent, would do that. If you live in Vancouver, which has ‘soft’ water, soap should work quite well instead of shampoo. If you live in Montreal or Kitchener/Waterloo, which have ‘hard’ water, not so much. ‘Hard’ water has dissolved salts of calcium and magnesium, and soap reacts with them to form a deposit: “soap scum”. You don’t really want that coating your hair after you wash it; you need a detergent other than soap.
Some other considerations:
- shampoos are pH balanced – between 5 and 8. Outside of that range, the cuticles will not lie flat.
- The detergent must not be too strong. If it is, it will remove all of the sebum, along with the dirt, and your hair will end up too dry.
- Shampoos always include a foaming agent. This has absolutely no use except to make the user feel as though the shampoo is working. If the shampoo doesn’t foam, people won’t buy it.
Even with a mild detergent, conditioners are helpful in replacing the sebum that’s been removed. How do conditioners work and what are their active ingredients? Conditioners are actually the same as detanglers, so they are just like that descrition above. Yes, you can use a conditioner as a detangler, especially the conditioners that are designed to be left on your hair and not rinsed off.
Final snippet: 2 in 1 Shampoo & Conditioners are great for saving time. You wash and condition your hair in one step, not two. But how do they work? How does the conditioner “know” that it should wait for the shampoo to remove the sebum before coating the hair? Clever chemistry holds silicones in suspension in a shampoo until the shampoo is rinsed away with a lot of water. So, during the shampooing the silicones are held in a sort of suspended state of animation. When the shampoo is washed out, the silicones are activated, coat the hair and leave it in good condition. The results can be pretty good, but still 2 in 1's can’t match the effectiveness of separate shampoo and conditioner.
1 comment:
I never knew why some people in some places can wash their hair with an ordinary bar of soap, but for other people it just makes their hair scungy. Thanks, Simon! Now the science of hair-washing makes a little more sense.
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