The Science of Hairstyling Heat Protection Products

Turtlefreak requests, “(…if this isn’t too out of left field:) maybe write a post about the
efficacy of heat protectant sprays? I can’t tell if this actually protects my hair or if I’m just buying placebo water in a spray bottle…”The first thing we need to address in order to really look at this question is: Why the hell is heat bad for our hair in the first place? When exposed to heat higher than 130 degrees Celsius (about 265 degrees Fahrenheit) your hair does three displeasing things:
1. Your hair’s internal moisture flees your hair.
2. The hair’s chromophores, the portion of the hair shaft that absorbs and reflects light, begins to break down.
3. The surface of the hair also breaks down, giving you radial and axial cracking across the hair shaft.In layman’s terms, you end up with dull-looking frizziness that is split-end central. (These effects, by the way, are dramatically worse if you heat-style your hair while it is wet. Because steam is trying to escape the hair, you end up with “bubbling and buckling of the cuticle”. Don’t do it, guys.)

I found some split ends in my hair yesterday.
It may be time for a haircut.

Turtlefreak asked about the efficacy of heat protection products in general. So, in this post, we’re going to look at two separate questions.

Firstly, are heat protection products effective?
Secondly, if they are effective, what is it that they are actually doing?

1. Are heat protection products effective?

Researchers in one study in the Journal of Cosmetic Science analyzed the efficacy of certain polymers and surfactants. They used a curling iron to induce damage under a variety of treatment conditions. Next, they looked for hair surface modification and texture changes in the heat-exposed hair. They also used florescence spectroscopy to analyze the decomposition of tryptophan, an amino acid that breaks down with heat and, in hair, is correlated with pigmentation.

PVP/DMAPA acrylates copolymer (sometimes sold under the trade name Styleze CC-10), Quaternium 70 (sometimes sold under the trade name Ceraphyle 70), and Hydrolyzed wheat protein (sometimes sold under the trade name Hydrotriticum 2000) all had measurable effects. Loss of tryptophan, for example, had a protective effect ranging from 10 to 20% for all three ingredients, even after the shortest amount of heat exposure. Sodium bisulfate was also tested. It showed a 15-23% protective effect after ten minutes of heat exposure, possibly due to its antioxidant effect. Basically: Hooray! This shit is doing it’s job.

The researchers also found some evidence suggesting that PVP/DMAPA acrylates copolymer may selectively bind to regions of the hair with damage, reducing the surface damage to the hair. (Quaternium 70, Hydrolyzed wheat protein, and sodium bisulfate failed to help with surface damage, with the latter showing some degree of damage.)

Thus, their research found at least some protective effect for every single material that they analyzed. However, based on their findings, PVP/DMAPA acrylates copolymer is probably the best ingredient, with Quaternium 70 and Hydrolyzed wheat protein being close seconds. Given that sodium bisulfate helped in some ways and hurt in others, you probably don’t want to use it as a major component of your heat protectant product.

(Cliffnote summary for all you skimmers out there: Quaternium 70 and Hydrolyzed wheat protein–> Good! PVP/DMAPA acrylates copolymer–> Best!)

If you specifically want to ensure that the products you are using contain one of these empirically-supported ingredients, you’re just going to have to look at the label. A quick google search shows that the Oscar Blandi Pronto Dry Styling Heat Protect Spray, for example, contains PVP/DMAPA acrylates copolymer. If you’re blowdrying curls, the Ouidad Climate Control Heat and Humidity Gel has both PVP/DMAPA acrylates copolymer and hydrolyzed wheat protein. The AG Hair Cosmetics Curl Spray Gel Thermal Setting Spray and the Drybar Hot Toddy Heat Protector Frizz Fighter are other options. Y’all can google this on your own. I believe in you. (Obviously, the higher up in the ingredients list, the more there is, so higher up is preferable.)

Although the research on those ingredients has been done, that does not mean they are the only ingredients that have value in terms of thermal protection.

According to the International Journal of Cosmetic Science, anything that treats your hair with a conditioner is a big thumbs up. In particular, the authors recommend low-molecular weight conditioners, like cetrimonium bromide, which are more effective at penetrating the hair shaft than other conditioning agents.

2. Why are heat protection products effective?

This question is even harder to answer because peer reviewed research demonstrating a concrete protection mechanism just isn’t available.

That being said, there are a few strong hypotheses. Some products may coat the hair in a buffering layer, which keeps your heat styling product from overheating the shaft of the hair itself. Some may limit oxidation reactions, which may be responsible for tryptophan-loss.

Either way, your hair protectant spray is probably not placebo water in a bottle, but you may want to check the ingredients (just in case).


1. Thank you so much for writing this! (Great post, too!)

2. Glad to answer your question!

3. Alright, you say not to style your hair when wet. Does this mean don’t blow dry? Like wait until your hair is dry and then curl/straighten?

4. The article I cited is specifically referring to heat styling, like straightening, but obviously blowdrying is bad for your hair as well… If you blowdry, I would definitely use a product to protect from the heat!

5., YOU ARE MY HERO. Thank you so much for your in-depth reviews and your no nonsense, no fucks given attitude!
(PS do you have a twitter?)

6. I’m afraid of social media!

7. I clicked on the picture of you looking incredulously at your hair (because lets face it your expressions are awesome) and noticed your earrings. Are those Serotonin molecules?

8. They are, and you are awesome for knowing that.

9. Can you do a post on your thoughts on Mineral Oil in skincare? There’s lots of debate on if its good or bad for your skin, I’d like to see you science it up. P.S. love you’re blog!

10. This is a good question! I’ll definitely answer this in the next week or so. (Spoiler: It is totally okay to use mineral oil on your skin.)

11. good info!! i use a lot of Hair styling products daily.