K18 Bond-Building Hair Treatment: Everything You Need to Know

TikTok made the buzz on the #K18HairFlipa hashtag created by the hair care brand K18, which has 10.6 billion views on the platform as of the date of this publication. Influencers like Mikaïla Nogueira (11.3 million followers) and Brad Mondo (8.7 million subscribers) have teamed up with the brand, and there’s a treasure trove of videos reviewing her incredibly popular Molecular Repair Leave-In Hair Mask. It was compared to Olaplex, featured in stunning before and afters, and got the 60-second review treatment. Yes, people love it – but at $75 it’s significantly more expensive than its competitors.

So what makes K18 different from traditional link building products? Is it a leave-in mask or conditioner? What hair types can use it, and How? ‘Or’ What do you use it? With the help of a few cosmetic chemists and several hairstylists, here’s everything you need to know about K18 before you reach it.

Meet the experts:

  • Suveen Sahibco-founder of K18 and Acquis. He is based in San Francisco.
  • Krupa Koestline, a cosmetic biochemist who has worked with brands that strive to create products of natural origin. She is based in Orlando, Florida.
  • Javon Ford, a cosmetic chemist who makes her own skincare products. On Tiktok, he shares his thoughts on popular beauty products with his 152,000 followers. He is based in Los Angeles.
  • Nathalie Ruzgishairdresser at Prosperous Hair Collective in Chicago.
  • Daniel Kima hairstylist who works in Los Angeles, as well as Austin and Dallas, Texas.
  • Jon Reymanbicoastal hairdresser and co-founder of Spoke & Weal Loungewhich has offices in Boston, Chicago, New York, Nashville, Palo Alto, Los Angeles and San Francisco.

What is K18?

Think of your hair as a ladder made up of links. Disulfide bonds are the horizontal rungs of the ladder. There are also polypeptide chains which are the sides of the ladder, connecting the rungs vertically. When our hair suffers any type of damage, these horizontal disulfide bonds can be broken – which is why bond builders have become more popular before, during and after chemical treatments, explains Suveen Sahib, co-founder and CEO of K18 research he and his team did to create the product. Most bond builders make the outer structure of the hair – the hair cuticle – look smooth, shiny and less damaged. As for the vertical polypeptide chains, however, they cannot be patched or “glued” together, which is where K18 comes in.

K18 works on a deeper level to molecularly modify and repair broken polypeptide chains, as well as reconnect disulfide bonds. “K18 replicates the entire structure of these polypeptide chains,” says Sahib. “When they break, [K18] goes in there and reconnects them as if they weren’t damaged, returning the strings to the state they were in before they were chemically damaged. It mimics the structure.”

This is why the brand refers to itself as “biomimetic hair care” – biomimetic meaning “to imitate biochemical processes”, because it works to restore the hair’s original structure. We sent a cosmetic chemist based in Orlando Krupa Koestline a list of K18’s ingredients, and she notes the “usual suspects” when it comes to ingredients found in hair care, such as quaternary ammonium salts, fatty acid alcohols, amino acids, and polymers. “I also see alcohol listed as a second ingredient on all of these products, which can dry out hair if not formulated correctly,” she points out.

David R. Brewer