full-size leave-in molecular repair hair mask
4-minute leave-in treatment to reverse hair damage
A leave-in treatment mask that works on the molecular level to reverse hair damage in just 4 minutes. The K18PEPTIDE™ is clinically proven to repair damage from bleach + color, chemical services and heat* – with immediate and lasting results to restore strength, softness, smoothness and bounce to hair.
20+ billion TikTok views 🔥
Get started here.
how does the k18 mask work?
The K18 mask works as a treatment to reverse damage in 4 minutes. It’s powered by our biomimetic K18PEPTIDE™ to seamlessly fit in and reconnect broken polypeptide chains at the molecular level. As a result, disulfide bonds are also reconnected for reinforced strength along the length + width of hair—offering comprehensive, lasting, and progressive repair.
what is the k18peptide™?
K18PEPTIDE™ is a biotech-developed peptide that mimics hair’s structure to reverse damage by reconnecting polypeptide chains and disulfide bonds broken during damage from bleach + color, chemical services, and heat*
*Disclaimers
why skip conditioner?
Conditioner leaves a film that blocks our peptide from penetrating effectively. Once the 4-minute wait time is up, feel free to use a conditioner, a leave-in, or any type of product.
i noticed there’s alcohol in the formula, isn’t that bad for you?
We like to keep our formulas minimal, only using the exact amount of ingredients needed to get the peptide where it needs to go. Here the alcohol serves as an agent to optimize the hair environment for the K18 mask to work on a deeper level. Our unique blend of 3 alcohols functions to open the hair cuticle so the K18PEPTIDE™ can penetrate the innermost layer of hair, reaching the broken polypeptide chains (keratin chains).
when should i expect to see results?
Most see results after 2-3 uses. The more damaged the hair, the more dramatic the results so it may vary depending on your hair type and level of damage.
Repair damage for hair like new* in 4 minutes.
1. Shampoo, do not condition. Towel-dry thoroughly.
2. Apply 1-3 pumps based on your length and density, starting at the ends and working up towards the roots.
3. Let sit for 4 minutes. Do not rinse out.
4. Comb, add styling product + style as usual. Use for 4-6 washes, then as needed.
*k18hair.com/disclaimers
See how K18 unlocks our community's expression
- Hair Repair
- Texture
- Frizz Control
- Shine
- Manageability
- Faith G.Verified BuyerReviewingLeave-In Molecular Repair Hair Mask SampleI recommend this productRated 5 out of 5 stars1 hour agoAmazing Texture
This product works so well on my curly hair so that the texture is fuller and the curl pattern is deeper. I use this once every few weeks since I do not shampoo my hair very often and it has improved quality of my curly hair.
KUK18Hair UK4 minutes agoThank you so much for the 5-star review, Faith! We're thrilled to hear the Leave-In Molecular Repair Hair Mask is enhancing your curl pattern and texture. 💙✨
- Юлія Ш.Verified BuyerReviewingFull-Size Leave-In Molecular Repair Hair Mask 50mLI recommend this productAge 35 - 44Hair Concern Chemical damageHair Type Grey Hair, Medium DensityMy Results Less Frizz, Visible Difference, Smoother Hair, Soft Touchable HairRated 5 out of 5 starsYesterdayThis mask is fantastic!
This mask genuinely delivers. My hair was dry and damaged from coloring, and after just the first use it felt noticeably softer and more manageable. Less breakage, less frizz, and split ends look better too.
KUK18Hair UKYesterdayThank you so much for the 5-star review! We're thrilled to hear our Leave-In Molecular Repair Hair Mask is delivering such fantastic results for your hair. 💙✨
- Tiffany A.Verified BuyerReviewingJumbo Leave-In Molecular Repair Hair Mask 100mLI recommend this productAge 45 - 54Hair Concern Heat damage, Fragile/brittle hair, DrynessHair Type Fine/ThinMy Results Visible Difference, Smoother Hair, Less FrizzRated 5 out of 5 stars2 days agoMade my hair feel stronger and smoother
I’ve been really impressed with the K18 Leave-In Molecular Repair Hair Mask. My hair is dry and prone to breakage, and after using this it felt noticeably softer, smoother, and stronger without feeling heavy or coated. It also helped with frizz and made my hair much easier to manage. A little goes a long way, and I like that it’s a leave-in treatment. I would definitely repurchase this.
KUK18Hair UK2 days agoThank you so much for the love! 💙 We're thrilled to hear the Jumbo Leave-In Molecular Repair Hair Mask is delivering the stronger, smoother results you hoped for! ✨
- Traci K.Verified BuyerReviewingMini Leave-In Molecular Repair Hair Mask 15 mLI recommend this productAge 55 - 64Hair Concern Chemical damage, Frizz, Fragile/brittle hair, DrynessHair Type Fine/ThinMy Results Less Frizz, Visible Difference, Less Breakage, Smoother HairRated 5 out of 5 stars2 days agoSo far…so good.
I have very long, ultra-fine, color-treated hair, and after a recent full highlight my hair became extremely dry, tangled easily, and felt much more fragile than normal. I was honestly worried that it had been over-processed.
I’ve only used K18 twice so far, but I’m already very impressed. My hair feels noticeably softer, smoother, and easier to manage, and I’m seeing less hair come out when I detangle it. The ends still need some extra moisture, but overall my hair feels healthier and much less rough than it did before I started using K18.
I was also concerned that it might make my very fine hair greasy or weighed down, but that hasn’t happened at all. I use a small amount, let it sit for the full four minutes, and it leaves my hair feeling soft without making it flat.
I know damaged hair doesn’t magically repair overnight, so I wasn’t expecting a miracle after one use. But after two treatments, I can already see and feel a real difference. I’m very happy with the initial results and plan to keep using it while my hair recovers from the over-processing.
KUK18Hair UK2 days agoThank you so much for the 5-star review, Traci! We're thrilled to hear you're already seeing such amazing results with the Mini Leave-In Molecular Repair Hair Mask. 💙 We can't wait to see how your hair continues to improve! ✨
- Samantha P.Verified BuyerReviewingFull-Size Leave-In Molecular Repair Hair Mask 50mLI recommend this productAge 35 - 44Hair Concern Dryness, Frizz, Split-Ends, Heat damageHair Type Curly/Coily, Medium DensityMy Results Less Frizz, Bouncy Hair, Visible Difference, Stronger Hair, Smoother HairRated 5 out of 5 stars3 days agoInstant results!
The way my hair instantly got hydrated simply after 3 pumps had me in a state of shock! And after styling, my hair was light and looking healthy!!
KUK18Hair UK3 days agoThank you so much for the love, Samantha! 💙 We're thrilled to hear you're getting instant results with our Full-Size Leave-In Molecular Repair Hair Mask! ✨