How Do Bond-Builders Really Work?

Dr. Michelle Wong explains how they do what they do, and also what they don’t do!

It’s bonding time

Let’s get straight into it:

What bond builders claim to do: they’re marketed as repairing broken disulfide bonds inside your hair, but solid evidence for true disulfide repair is limited and controversial, especially regarding early claims made about Olaplex.

^{A note on chemistry: of the three main bond types going on in human hair, disulfide bonds are the strongest and most structural, ionic or salt bonds are medium strength, and hydrogen bonds are the weakest but very numerous and constantly breaking and reforming with water, heat, and humidity.}

What most bond-builders actually seem to do: the best available evidence suggests most bond builders work mainly by forming lots of hydrogen bonds and sometimes ionic bonds with hair proteins, which helps block water from entering and breaking your hair’s natural hydrogen bonds, making your hair less fragile when wet or humid.

Now, blocking water is important, because water disrupts hydrogen bonds between keratin proteins, so if a molecule can sit between proteins and form multiple hydrogen bonds itself, it acts like a more stable “bridge,” reducing swelling and mechanical weakness.

So, what’s in the products that do this? It varies a lot, but common candidates include small acids like maleic acid, succinic acid, malic acid, and citric acid, as well as ingredients like peptides and panthenol, which can hydrogen-bond with keratin; some brands use specialized peptides such as those in K18, which have comparatively stronger published evidence for penetrating and improving hair properties.

However, the science is pretty hairy: most hair research is industry-funded, independent funding is scarce, many studies lack proper controls, and companies often publish only a fraction of their data (specifically, the data that best supports their claims, while holding back data that calls their claims into question or outright contradicts them), making it difficult to directly compare ingredients or formulas.

On which note, the formulation matters as much as the ingredient, because even if an ingredient can hydrogen bond, the overall product determines whether it penetrates your hair, spreads evenly, and also conditions the surface, because rough, under-conditioned hair can feel worse and break more easily even if internal strength improves.

^{Illustrative analogy: if you buy all the correct materials to build a house, and then put those correct materials in a heap, the result will not necessarily be a well-built house with correct structure and such.}

In summary, bond builders don’t magically rebuild every broken disulfide bond (sometimes they don’t even rebuild any disulfide bonds at all), but many can meaningfully improve strength, reduce fragility when wet, and help manage chemical damage, especially when matched to your hair type and level of damage.

For more on all of this, enjoy:

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Take care!