K18 vs Olaplex hair masks: Which treatment for damaged hair is really the best?

Buy now£26, Lookfantastic.com

The best-selling hair treatment in the Olaplex line-up, this product uses the brand’s bond-building patented and ground-breaking hair tech. So we don’t lose you in the science of it, in the most simplified form it works by infusing strands and repairing broken bonds that go to make up the hair structure.

These bonds are often damaged from salon trips and daily aggressors, manifesting in frizz, dryness, breakage and so on. By doing so, it promises to repair damage, strengthen strands and reduce breakage in all hair types.

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It’s a pre-shampoo treatment, so you apply it to damp hair before shampooing – leaving a generous amount of the creamy product combed through for 10-minutes. This makes it much more convenient to use than standard masks and treatments, as you can apply and go about your daily routine without any shower time-wasting while it gets to work.

Our tester has long been a fan of this product but hasn’t used it in a while. After re-introducing it back into her routine, she had forgotten how much stronger her hair feels when using it at least once a week. Dry, brittle strands started to feel softer and look healthier the more we used it, and the same goes for less breakage and shower fallout.

Buy now £55, Cultbeauty.co.uk

Similar to Olaplex (£26, Lookfantastic.com), this treatment has a patented ingredient – but in this formula, the lead is the K18Peptide. Our hair strands are made up of keratin chains that become weak and break when hair gets damaged, and the brand says this peptide travels to the inner layers of hair reconnecting these broken chains – promising to bring damaged hair back to its original, youthful state.

Where this product differs to the Olaplex formula is in use. You apply it to freshly shampooed strands, skipping the conditioner. After, towel dry the hair and apply the concentrated cream. We thought this could end in tears as a detangling product is usually a must for our tester, but the treatment feels conditioning so with the help of a wide-tooth comb we quickly got through any knots.

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A little of the product goes a very long way, and you can use anywhere from one to four pumps. Our medium-length, medium-textured hair only needed two to cover the whole head once combed through. It’s a leave-in formula compared to Olaplex, which is a washout. Leave on for four minutes and then style as normal, without rinsing. Easy!

We trialled as the brand recommends, using it for up to six consecutive washes and then every three-four after that. After one use, there was a marked improvement in how much stronger and healthier hair felt and looked. However, with ongoing use expect the best results to come a few applications later (it did for us) with hair feeling extra silky soft and looking glossy after four-five applications.