Bond Building Products: Part 2, Lab Testing

 Part 2

Does Olaplex work (does it do what it claims to do?) ©Science-y Hair Blog 2024

A team of Italian researchers published an article in the International Journal of Biological Macromolecules recently putting 2 bond-builders to the test, Olaplex and Lunex Restore.

They used the active ingredients alone to avoid interference from the product-base (the conditioners and thickeners for example), as well as the whole product. They applied treatments to hair that had been bleached 3 or 5 times. The “bleached three times” thing sounds like overkill - but it is what was described in the patent literature. ©Science-y Hair Blog 2024

Hair was then treated for 45 minutes at warm room temperature (77°F / 25°C) with the bond-repair agents.

Testing

The researchers used 2 different kinds of spectroscopy. These methods shine light through a sample and measure the way the light is absorbed by hair with and without the product.

These methods can distinguish the amount of different kinds of chemical bonds - which is relevant because Olaplex claims to rebuild disulfide bonds by creating linking bridges, could result in an increase in apparent disulfide or covalent bonds in treated hair.

Disulfide bonds are between 2 sulfur molecules in the protein structure.

Science-y Hair Blog © 2011 by  Wendy M.S. is licensed under CC BY-NC-ND 4.0 

Results

The Lunex product (Shikimic acid) yielded no changes in disulfide bonds. The active ingredient was incorporated into the cuticle, and some of the cysteic acid content was decreased, though that may have been a result of the product pH rather than the product’s active ingredient. Or it could be both.

Olaplex (dimethyl maleate and  bis-aminopropyl diglycol dimaleate): “The disulfde bridges and cysteic acid contents did not significantly change upon the treatment.” Some of the active ingredient may have done some cross-linking, but mostly there were mainly electrostatic (ionic) bonds forming, not cross-linking. ©Science-y Hair Blog 2024

Summary of the product testing results based on product-claims. The product-claims are in the column on the left. Click to make this bigger and not fuzzy!

A difference was noted in the orientation of cuticles on the product-treated hair as more smooth or close to the hair surface - whereas chemical damage usually leaved cuticles elevated away from the hair surface. In fact, the researchers suspected that the changes resulting from these products may be occurring in the cuticles rather than in the cortex. Elevated cuticles are easily broken, and tend to make hair feel more dry and damaged. ©Science-y Hair Blog 2024

The take-home message is that product claims of re-forming sulfur bonds through cross-linking could not be documented by these kinds lab testing. Some changes were detected in the hair cortex and cuticle. They are not necessarily the changes promised by the product literature. They may interact with those broken sulfur bonds, but it isn’t clear yet how. Yes, these products did have an effect on the hair.

It’s possible that the changes occurring in hair that need a different method of testing to be identified. The authors were very forthcoming and detailed about how they interpreted their results - which is ideal. ©Science-y Hair Blog 2024

It would be helpful to have compared unbleached hair, and also to have compared all the bleached hair samples to the product base alone with no active ingredients.

Do they live up to the claims?

Maybe a little. Do they actually work? That’s a different question. The active ingredients are able to penetrate the cortex and deposit in/on the cuticle. There were ionic bonds taking place in those regions. Not only are the active ingredients affecting hair, the product’s other ingredients and pH are making changes. Those may not be long-lasting changes, like with other treatments. 

A quick refresher - the epicuticle (the f-layer with 18-methyleicosanoic acid) slows down water uptake - but is mostly eroded on the damaged, porous hair below. The cuticle layer with proteins is partly eroded, but can bond with conditioning ingredients to reduce static, add lubrication. Low molecular-weight ingredients can get into the cortex.©Science-y Hair Blog 2024

Water drop slowed down by epicuticle (right), moving through cuticles (left).

The protein cortex of hair is water-loving. Active ingredients here that slow water-loss - or aggressively retain water - help keep hair flexible and feeling hydrated.

Ingredients that can deposit on the hair and penetrate the cortex have a good chance of providing longer-lasting hydration. Hydration gives hair flexibility, bounce, and resilience in your daily activities. ©Science-y Hair Blog 2024

Watch on YouTube. 

 IN PART 3 – the proliferation of “other” bond-building products and what they’re up to.

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References:

Barreto T, Weffort F, Frattini S, Pinto G, Damasco P, Melo D. Straight to the Point: What Do We Know So Far on Hair Straightening? Skin Appendage Disord. 2021 Jun;7(4):265-271. doi: 10.1159/000514367.

Chemical and Physical Behavior of Human Hair 

Robbins, 1994. 3^rd Ed. Springer-Verlag, New York

Hessefort Y, Holland BT, Cloud RW. True porosity measurement of hair: a new way to study hair damage mechanisms. J Cosmet Sci. 2008 Jul-Aug;59(4):303-15. PMID: 18818850.