01 / THE DETAILS
What bleaching changes
Hair is built from keratin proteins with several kinds of interactions, including disulfide, hydrogen and ionic bonds. Bleaching can oxidize sulfur-containing structures and affect both cuticle and cortex. Different types of damage cannot be described with one percentage.
The chemistry matters because a product that improves combability may be useful without literally rebuilding every original crosslink. Good cosmetic performance and complete molecular restoration are not equivalent statements.
02 / THE DETAILS
How to read a product comparison
Olaplex and K18 describe different proprietary approaches. A head-to-head claim needs a clear test protocol, matching hair samples, controls, product dose and outcome measure. Tensile strength can describe mechanical performance; it cannot by itself count how many disulfide bonds have been reconstructed.
We previously reviewed a comparison involving tensile measurements. Its percentages should not be quoted as “percent of bonds repaired.” That would change the meaning of the experiment.
03 / THE DETAILS
What matters to a real client
A treatment can still be worth considering if it improves manageability or helps hair withstand routine handling. The right choice depends on colour history, breakage, texture, cost and the product instructions. Neither brand can reverse every effect of severe bleaching.
I treat bond-focused products as one part of a broader plan: thoughtful processing, conditioning, gentle mechanical care and realistic future colour goals.
Further reading
Research and technical reference:
View the published scientific source ↗Hair care product claims and individual responses vary. This article is educational and does not replace a personal professional assessment.