Hair Science! Any thoughts?

**Ddeathflower** · September 3rd, 2023, 08:11 AM

I just came across this scientific paper, while I was researching the properties of sebum, about how UV radiation and washing the hair with a surfactant (sodium lauryl sulphate) damage the hair cuticle (the outermost layer of the hair strand) which causes shine loss, roughness increase and split ends and on the cellular level they cause fracturing, cavities, cuticle cell lifting and, with surfactant washing, removal of cuticle cells. Lipids, pigments and proteins, which are major constituents of human hair, are modified by solar radiation, resulting in drier, rougher, more brittle, and opaque hair strands, in addition to the loss of their mechanical strength, color changes and the formation of split ends.
I thought this was a fascinating find and wanted to hear what people here thought of it!

I'm about to start a sebum-only journey hence all my research into the properties sebum. I've learnt that Sebum has hydrophobic properties so it keeps moisture in the hair but stops too much from getting in to it externally and also protects the scalp and hair from uv-radiation, bacteria and fungi.

**Ddeathflower** · September 3rd, 2023, 09:04 AM

Just a small note, that this is washing without conditioner, which adds a protective film to hair that fills in any gaps in your cuticle which stops more forming and protects the hair from tangling and damage. I found a really informative youtuber who is actually a chemist phd and cosmetic chemist who goes into the science behind shampoos and conditioners detailing what all the ingredients are and their purposes in the formulas.

**mochichichi** · September 7th, 2023, 11:58 AM

From their methods:

Hair samples were daily irradiated for 10 h, using a mercury lamp full-spectrum (UV, VIS and IR), which was followed by a period in the dark (> 14 h), after which the sequence was repeated cyclically, until completing a total irradiation of 230 or 600 h. Two washing conditions were combined to the irradiation steps: 1. hair strands washed after each 10 h irradiation cycle (totalizing 23 or 60 washings in samples irradiated for 230 and 600 h, respectively), and 2. hair strands that were not washed, only irradiated. The effect of washing alone was evaluated in samples that were not irradiated, but only washed for 23 or 60 times.

I'm kind of skeptical that their goal of simulating daily conditions was met by irradiation for 10 hours (they say this is equivalent to 5 hours in the sun in Brazil where the study was conducted) and then immediate washing with an SLS solution--I would also have liked to see that the concentration of the SLS was comparable to something in common shampoo products (if someone else sees this and I missed it please share). I'm sure that there are people who are outside a lot during the day, but most of the people I know who are tend to wear hats or headcoverings--of course this is my experience where I live and I'm sure this is relevant to plenty of people.

**Ddeathflower** · September 7th, 2023, 02:39 PM

The paper says it was washed in a solution containing sodium lauryl sulphate.. I'm assuming they formulated it with a shampoo recipe? It's difficult to tell without reading the full paper but that costs money. :'(
I think this study isn't so much fear mongering about washing with sulphates and letting your hair catch sun damaging your hair as opposed to just proving that they do cause damage and what type of damage occurs.
Keep in mind these hair strands do not have sebum on them, and they didn't condition the hair samples after washing so this hair sample didn't have the same protection our actual hair has.
I just thought it was neat to see what happens at a cellular level when the hair is exposed to those conditions.
I now realise there is a hair science thread already made I could have posted in so don't I feel foolish. :'D

**mochichichi** · September 8th, 2023, 02:35 PM

Originally Posted by Ddeathflower

The paper says it was washed in a solution containing sodium lauryl sulphate.. I'm assuming they formulated it with a shampoo recipe? It's difficult to tell without reading the full paper but that costs money. :'(
I think this study isn't so much fear mongering about washing with sulphates and letting your hair catch sun damaging your hair as opposed to just proving that they do cause damage and what type of damage occurs.
Keep in mind these hair strands do not have sebum on them, and they didn't condition the hair samples after washing so this hair sample didn't have the same protection our actual hair has.
I just thought it was neat to see what happens at a cellular level when the hair is exposed to those conditions.
I now realise there is a hair science thread already made I could have posted in so don't I feel foolish. :'D

Yeah, I have access to the full paper and I don't see how they formulated their SLS solution anywhere, but I didn't read super super closely. Also not only do they not have sebum but the hair was actually cleansed before starting. I didn't look at how that was done but it was according to a previous publication.

**spidermom** · September 8th, 2023, 04:07 PM

You have to think about the health of your scalp as well. I've been washing my hair and scalp less frequently because I recently had surgery on one of my feet and have to stay off it as much as possible and keep the surgical site clean and dry. I comb and brush my hair every day to keep the sebum from collecting at my scalp. I wash it once a week. I am noticing that I'm getting little itchy bumps on my scalp which I've had before and was diagnosed as seborrheic dermatitis. My hair is fine with being washed once per week, but my scalp is not.

Your experience may well be different, but pay attention to what your scalp is doing.

**Jovana** · September 8th, 2023, 07:10 PM

Maybe you should wash your hair in a salon during recovery, scalp is skin and skin is a important organ to the immune system.

**GordonMurphella** · September 10th, 2023, 04:53 AM

Originally Posted by moonreader

A good haircare routine isn’t just about the products we apply, “make sure to eat a good diet, organic where possible, and drink plenty of water. We really are what we eat,” says Cant. “Feeling truly beautiful is a much deeper story than simply taking care of the outside, it’s a vibrancy that transcends from deep within. Our hair and skin simply reflect what is being created on the inside.” contributed by Ohcans candle

This is the third post where you mention this ... candle company. Please don't shill here. Thanks.

**mochichichi** · September 10th, 2023, 08:43 AM

Originally Posted by mochichichi

Yeah, I have access to the full paper and I don't see how they formulated their SLS solution anywhere, but I didn't read super super closely. Also not only do they not have sebum but the hair was actually cleansed before starting. I didn't look at how that was done but it was according to a previous publication.

Also, I say they were trying to mimic real conditions because they say they were trying to mimic real conditions.

**maborosi** · September 10th, 2023, 06:27 PM

Originally Posted by spidermom

You have to think about the health of your scalp as well. I've been washing my hair and scalp less frequently because I recently had surgery on one of my feet and have to stay off it as much as possible and keep the surgical site clean and dry. I comb and brush my hair every day to keep the sebum from collecting at my scalp. I wash it once a week. I am noticing that I'm getting little itchy bumps on my scalp which I've had before and was diagnosed as seborrheic dermatitis. My hair is fine with being washed once per week, but my scalp is not.

Your experience may well be different, but pay attention to what your scalp is doing.

Oh, my, Spidermom! I'm wishing you a speedy recovery!!

I am right there with you. Some of it probably has to do with my climate ,too. But I absolutely have to do daily scalp washes. The rest of my hair is fine with very infrequent washing, but oh, my...if I miss even one day, I get a breakout all over my scalp and on my hairline!