If you haven’t heard of K18 yet, prepare to hear a lot more. It’s the new(ish) hair repairer on the block, boasting a unique peptide technology that threatens to take the shine (and strength, and elasticity) off market leader Olaplex. We delved deeper (and gave it a good testing, obviously) to find out more…

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It seems like only yesterday that Olaplex  burst onto the hairdressing scene, offering up a hair-healing treatment that allowed us to continue chemically colouring our hair, but without the damaging side effects  (it actually launched in the UK around eight years ago – doesn’t time fly when you're having good hair days?).

The marketing teams behind other haircare brands quickly jumped on the craze, launching 'plex' and 'bond' products, some of which appeared to work on a deeper level, rebuilding the same disulfide bonds  damaged by chemical colouring, while others took a more 'cosmetic' approach, sealing split ends and raised cuticles using light-reflecting, silicone-based formulas. There’s nothing wrong with a styling cream that gives you the best, bounciest, shiniest blow-dry of your life, but in terms of genuine hair 'healing' nothing has caused a stir quite as big as Olaplex… until K18 reared its glossy head, that is. It's already garnered a celebrity following among the likes of Selena Gomez, Rihanna and Hailey Bieber. Khloe Kardashian Instagrammed that she was "obsessed" with the bond repair treatment after her stylist recommended it. "It literally brought my hair back to life," she said.

Is K18 better than Olaplex?

Both offer an in-salon and at-home damage-repair system for colour-treated hair. As with any product, the results can differ depending on your hair type; what suits yours might not suit your friend’s. Oh, and neither is worth the spend if you don’t have any damage (i.e. if you don’t heat style or colour repetitively). Both products are designed to seek out and repair severe chemical and heat damage, so if yours doesn’t come into contact with either, you’re best off treating yourself to a more affordable moisturising hair mask  every now and then.

Looking into the science behind K18 (originally known as Khairpep before its rebrand), it approaches damage repair in a different (and arguably more advanced) way. Although it’s worth pointing out that no independent scientific trials have been carried out on either, the impressive before and after shots speak for themselves, as do the hairdressers choosing to use them in their salons.

Image: Instagram @ivyloungehairbeauty

“I have a client who has naturally frizzy, grey hair that’s coloured, but not over-processed,” colour director and co-founder of Four London  Brooke Bohan tells us. “We’ve always struggled to get moisture into her hair, so I decided to trial K18 and was amazed! It was instantly silky, beautifully conditioned and smooth. I started using it on other clients and continue to be amazed at the results I’m getting.”

Beauty directors are also having their heads turned after experiencing the K18 in-salon treatment, including Get The Gloss very own Victoria Woodhall (below) who, after a long period of air-drying her fragile hair to avoid damage, was able to return to heat styling thanks to the game-changing at-home leave-on mask, which is used in tiny amounts in place of conditioner.

"I was really nervous about not using conditioner, but the K18 Mask gave me a really smooth blow-dry and I was amazed by the condition – I didn’t miss my conditioner at all," she says. "I have used Olaplex in the past, but prefer this because it means I use fewer products and get a great style, too."

Victoria's colourist Charlie Double at Four London explained that Olaplex would probably be redundant on her hair as it wasn't damaged enough. "She advised that Olaplex would be more suitable for hair that had been bleached."

Beauty editor Nadine Baggot, who posts about her own solutions for thinning hair  is a fan of both, using Olaplex 0 when she colours her hair and the K18 mask for styling.

How does K18 compare to Olpalex?

The hero ingredient in Olpalex is bis-aminopropyl diglycol dimaleate (try saying that after a glass of wine), which actively targets and restores broken disulfide bonds that link our hair's protein strands. K18 promises a similar result but instead sends a patented peptide (K18Peptide) into the inner structure of the hair, where it replaces lost amino acids and regenerates the entire keratin chains responsible for retaining hair strength and softness.

Think of your hair as a ladder: disulfide bonds are the horizontal rungs of the ladder, and polypeptide chains make up the sides of the ladder, connecting the rungs vertically. While Olaplex reconnects broken disulphide bonds, K18 claims to target the "sides of the ladder" and ‘reconnect broken polypeptide chains and cleaved disulphide bonds’ using biomimetics (the practice of learning from and mimicking nature).

Do you use K18 and Olaplex differently?

Both brands offer a three-step system, with steps one and two taking place in-salon during a colour appointment, and step three being an at-home mask. Olaplex has since launched other numbers, including No. 0, which boasts the highest dose of any take-home Olaplex technology and can be used as a boosting primer for No. 3, (keeping up?!).

But how the at-home hair masks are used sets the two brands apart yet again. Olaplex Hair Perfector No.3, £26 is a once-a-week treatment, left in for a minimum of ten minutes before being washed out. The K18 Leave-In Molecular Repair Hair Mask is used more like a leave-in conditioner, with added lightweight conditioning benefits to keep hair smooth and soft. You leave it on wet hair for four minutes, then style as usual without washing it out. You should ideally use it for the first 4-6 washes, and then every 3-4 washes as needed.

Is there a big price difference between the two?

Ermm… you could say that. While the Olaplex No.3 at-home mask comes in at £26, the equivalent 100ml of K18 would put you back £110! (50ml is the largest bottle for £55). So, we’re not talking a few extra pennies here. That said, with the K18 mask, we’ve cut out conditioner and other styling products (don't ditch the heat protector, however) and are only using the tiniest amount – we’re talking a blob that sits on the tip of your little fingernail, compared to Olaplex’s No.3 which requires a 'generous amount'. As for the price and time your spend in-salon. K18 is slightly quicker and cheaper at £20 for the four-minute treatment (at Four London) and includes a sample size of the take-home mask, while Olaplex costs £20 and the takes around 15 minutes.

Olaplex No.3 at-home mask , £26 (100ml)

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Olaplex v K18: the conclusion

Still on the fence about which one to go for? “At the end of the day, it becomes a matter of choice for the hairdresser and the client,” says Brooke. “We have clients who don’t like – or suit – Olaplex, so with K18 coming along it gives us, as hairdressers, options.”

The good news is, they can both be used together because one is a pre-wash the other a post-wash and they repair in different ways.

So, if you’re reluctant to give up your in-salon Olaplex treatment, but fancy ditching conditioner and styling products by utilising the leave-in benefits of K18 – try using both… if your budget allows. Neither can be considered affordable, but both are, without a doubt, game-changing.

So, will K18 officially take the crown? Watch this space…

A K18 treatment costs £20 at Four London and Olaplex costs £30

Buy K18 at-home treatment here