As someone who has been dying their hair since the tender age of 13, having lived through more disastrous home bleaching scenarios than I care to remember, I can confirm that few things have revolutionised hair care than the arrival of Olaplex and the explosion of bond-repair hair products which ensued as a result.
Initially only available in-salon, since launching its first at-home bond-rebuilding treatment No.3 Hair Perfector, Olaplex has gone stratospheric.
But now there’s a new brand taking over TikTok – and Hailey Bieber and Rihanna are both already fans.
What is K18?
K18 launched into the UK early 2022 with its Leave-In Molecular Repair Hair Mask: a treatment which promises to restore damaged tresses in four minutes.
Much like Olaplex, there’s a lot of cool science behind the brand. K18 Biomimetic Hairscience draws on a decade’s worth of research in the lab spent mapping out the different amino acid sequences that make up human hair.
Scientists discovered a peptide that was the ‘perfect size and shape’ to repair the innermost layers of the hair shaft, by ‘mimicking’ the natural structure of keratin chains. And so the patented K18 Peptide was born.
How does K18 differ to Olaplex and other bond-building treatments?
Everything from colouring to thermal styling, pollution to hard water can damage our hair.
Jordan Alexander, senior director of global sales and education at K18, says we should think of the hair shaft under a microscope as a ‘ladder’ on which the K18 peptide delivers a two-pronged attack.
Bond builders like Olaplex relink broken disulfide bonds on the horizontal rungs of the ladder, whereas K18 deals with the entire ladder, starting with the vertical lengths on each side, also known as polypeptide (keratin) chains, before also reinforcing those horizontal rungs.
The result? Stronger, shinier and more resilient strands (apparently)…
K18 Leave-In Molecular Repair Hair Mask: a review
I’m always looking for ways to shave minutes off my morning routine, so for me the beauty of K18 is firmly in its convenience, because you actually don’t have to rinse it out. After shampooing your hair, you simply towel dry, no conditioner necessary.
Apply a pea and a half-sized amount – it goes a lot further than you’d think – and leave on for four minutes before styling.
When you first start applying the K18 mask, the brand recommends you use it straight after shampooing for the next four to six washes, then drop down to every third or fourth. But for me, this has replaced conditioner completely.
Most leave-in products can leave my very fine hair feeling weighed down and greasy. Surprisingly, this doesn’t.
There’s also no visible leftover residue and my hair instantly feels and looks thicker and fuller – although I should add, K18 doesn’t claim to promote hair growth.
I’ve now ditched conditioner and hair serum altogether, both of which I’d normally need to detangle after washing.
The mask is suitable for all hair types, but if your hair drinks up moisture you could apply an additional conditioning product after.
At £55 for 50ml, it is more expensive than Olaplex’s No.3 Hair Perfector and No.8 Bond Intense Moisture Mask (both £28 each for 100ml) but as you only need a teeny tiny amount (and because of the results), I’d argue it’s worth the splurge.
How do K18’s new shampoos perform?
Both shampoos contain a ‘microdose’ of the K18 peptide to prevent protein loss. The idea is they help to create a ‘healthy canvas’ so that you get more out of the mask. Both are suitable for all hair textures, though how often you use them will vary accordingly.
K18 Peptide Prep Detox Shampoo, £39 for 250ml
Of the two shampoos, this was the standout product for me. The non-stripping formula contains activated charcoal and salicylic acid to mop up dirt, toxins and excess sebum, while removing metals found in hard water like copper.
It’s like a jet wash for your hair and scalp and left my blonde locks looking noticeably brighter. Use it once a week if, like me, you’re prone to build-up or use products like dry shampoo regularly.
K18 Peptide Prep Ph-Maintenance Shampoo, £39 for 250ml
I saw less of an obvious difference to my hair after using this, but I did like the way it worked into a satisfyingly foamy lather thanks to non-harsh plant-derived surfactants, which left it feeling really clean but not parched.
The maintenance shampoo is pH-balanced, too, meaning it won’t disrupt the natural environment of the scalp, even if you use it every day.
At £39 each, there’s no denying these are pricey shampoos. By comparison, Olaplex’s No.4 Bond Maintenance Shampoo – which I also love – costs £28 for 250ml.
K18’s Detox serves a slightly different purpose, though, and as the best clarifying shampoo I’ve ever used, I can see myself buying it again. If you’re prone to product build up, greasiness or colour fade, this is a worthy investment in my eyes.