What’s up, everyone? The second post in this science series is about henna. Do you use henna? I can’t forget my disclaimer. I am not a hair scientist, dermatologist, trichologist or anything like that. I’m just someone who loves science and hair and I want to share it with you.
Henna is very popular among healthy hair enthusiasts. It has been used for Ayurvedic treatments for years. In this part of the world, it is primarily used for beautifully decorated skin art.
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There is a reason you cannot get a henna done at any reputable salon. It DESTROYS your hair. From the cuticle to the cortex, it causes permanent, irreversible damage. That initial softness and "curl loosening"? A pulverized cortex. That resulting hardness that you mistake for "strength"? The cortex hardening into an un-moisturizable (its a word, today), un-conditionable (that, too) hot ass mess. It is a permanent process. And you guys do it over and over again. If it were actually safe for your hair health, STYLISTS WOULD OFFER THEM IN SALONS. There are a myriad of ammonia and peroxide free haircolor options so I have no idea why some of you would choose a product that advises you in the actual instructions to mix with conditioner to avoid breakage. I'm mystified… And if you want to loosen your curl pattern, just get a relaxer. #BeTeamNaturalFORREAL #Truth #StopGettingYourHaircareAdviceFromTheCommentSection #jrjnyc
I saw this post on Instagram by Jennifer-Rose. Jennifer is a popular hair stylist in New York and she specializes in hair color and natural hair. She appeared on Taren Guy’s salon series. I was curious to know why she hates henna so much. I tried using henna once and I was curious about the science behind it. When that curiosity piques, I head over to my good buddy, Google, to help me out.
Henna is also known as Lawasonia inermis. It is a plant used for hair dyeing and body art. The henna leaves are typically ground into a powder.
Inside the plant cells is the lawsone molecule. The lawsone molecule is responsible for the dying and possible change in hair structure. In order to get the lawsone molecule out of the plant cell, one needs to break down the cell wall. Plant cell walls are pretty strong and made of cellulose. Most henna procedures require using some acidic liquid (tea, lemon juice, etc.) to mix the powder into a paste. This paste is usually left for several hours to a day. The acid helps to break down the cellulose and release the lawsone molecule. Once the molecule is free it can easily bind to one’s hair.
The lawsone molecule has an extremely high affinity to keratin. This means that it really, really, REALLY likes to bind to keratin. Keratin is one of the major components of hair. It binds via a process called the Michael Reaction. Even though the Michael reaction is reversible, henna application for hair is essentially permanent. To remove henna, one needs to strip it peroxide or bleach. 😯
Many people have noticed a difference in hair texture with prolonged use of henna. [Lipstick Alley, Minimalist Beauty] I think the strong binding of lawsone to keratin may attribute to this effect. Henna is a deposit-only dye. This means that it attached to the hair cuticle. It is different from other penetrative dyes that lift the hair cuticle and attached to the inner parts of the hair. It is possible that over time the continued depositing of henna adds weight to the hair which may elongate the curls.
My major concern with henna is that it may affect how my hair processes when I relax it. I also don’t want to change my hair color. Cassia obovata is an option for those who don’t want to color their hair. I didn’t find too much information about how it binds to hair. However, it doesn’t stain your hands like henna does so it may be possible that the affinity is not as strong as henna.
Do you use henna? What is your experience?
A quantitative study of dyeing with lawsone B. I. H. AMRO, K. C. JAMES, and T. D. TURNER, J. Soc Cosmet. Chem. 45, pp 159-165 (May/June1994)
The chemistry of henna – Cthuliz ()