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4.7
Rated 4.7 out of 5 stars
7,918 Reviews

full-size leave-in molecular repair hair mask

4-minute leave-in treatment to reverse hair damage

Description

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 🔥

*Disclaimers

Repairs Damage Caused By

  • Bleach + Color
  • Heat
  • Chemical Services
  1. Shampoo, do not condition. Towel-dry thoroughly.
  2. Apply 1-3 pumps of K18 leave-in molecular repair hair mask 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 product + style as usual. Use for 4-6 washes post-salon service, then as needed.
  • K18PEPTIDE™ is a biotech-developed peptide that mimics hair's structure to reverse damage by reconnecting polypeptide chains and disulfide bonds broken during bleaching, color and chemical services + heat*.

  • pH-optimized (5.0-6.0) to help minimize cuticle swelling + put hair proteins in their most resilient state.

  • Cream format enables easy, lightweight application across all hair types, with detangling and softening benefits.

  • Vegan, color-safe, cruelty-free.

Takes damage repair further – reconnects both polypeptide chains (and as a result, also reconnects disulfide bonds) for strength along the length + width of the hair - offering comprehensive, lasting damage repair.

Restores hair from even extreme damage - by working at the innermost layer of the hair, core strength and elasticity are renewed for strong, smooth, bouncy hair.

Delivers immediate and lasting results – hair is repaired from the first use and lasts past your next wash, for ongoing reparative benefits.

Simplified repair - convenient, leave-in formula works in just 4 minutes, with no extra rinse required.

Works on all hair types – because K18PEPTIDE™ works on a molecular level (where all hair is the same), this product is effective on all hair types.

  • DO clarify before K18 if you’re a heavy product user (demineralize for mineral + metal buildup).
  • DO apply on clean, damp hair.
  • DO wait the full 4 minutes before combing or styling.
  • DO add whatever styling products you love after the 4 minutes.
  • DO use for 4-6 shampoos consecutively for progressive results.
  • DON'T use conditioner before applying K18 Mask (you can apply after the 4 min but most find they don’t need it).
  • DON'T overdo it—less is more.
  • DON'T rinse it out.

Water (Aqua) (Eau), Alcohol Denat., Propylene Glycol, Cetearyl Alcohol, Dicaprylyl Ether, Cetyl Esters, Behentrimonium Chloride, Polysorbate 20,sh-Oligopeptide-78 (K18PEPTIDE™), Hydrolyzed Wheat Protein, Hydrolyzed Wheat Starch, Isopropyl Alcohol, Tocopherol, Phenoxyethanol, Potassium Sorbate, Citric Acid, Fragrance (Parfum), Geraniol, Linalool, Hexyl Cinnamal, Benzyl Alcohol.

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Description

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 🔥

*Disclaimers

got questions?
Get started here.
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.
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*

*k18hair.co.uk/disclaimers
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.
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).
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.
powered by K18PEPTIDE™

Biomimetic peptide clicks into hair’s keratin structure—the source of core strength—for soft, shiny, bouncy results that won’t wash away.

how to use molecular repair mask
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.
feel what's possible with K18
See how K18 unlocks our community's expression
4.7
Rated 4.7 out of 5 stars
Based on 7,918 reviews
7,918 reviews
  • Samineh S.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Rated 5 out of 5 stars
    15 hours ago
    The Best

    Probably the best hair mask I have used over the past 20 years. My hair was extremely damaged and very dry since using this product I’ve even stopped using a conditioner as this does everything. Amazing. Definitely recommend.

  • Esme T.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Rated 5 out of 5 stars
    15 hours ago
    Amazing

    Genuinly didn't think this was possible. I had 2 years worth of bleach, box dye, extentions and hair loss due to medical reasons. My hair was fried and I didn't want to chop it all off and start again. 3 months of k18 and my hair has never looked better! The photos attached are taken by my hairdresser who recommended the product to me. They are 12 weeks apart.

    The small bottle really goes a long way. As my hair got healthier my curls got better as well!! Couldn't recommend this product more :)

  • Marlene T.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 35 - 44
    Hair Concern Color-care, Split-Ends
    Hair Type Fine/Thin
    My Results Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    15 hours ago
    Nice product

    Used right after I bleached my hair. Seemed to help keep it healthy!

  • Hilary F.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Heat damage, Split-Ends
    Hair Type Medium Density, Straight/Wavy
    My Results Less Frizz, Less Breakage, Smoother Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    Yesterday
    Soft and sleek

    This is my first time trying k18 after reading more about how to improve my hair health and maximize growth. Bond treatment evidence seemed to be the best option and may sources recommended this product. I have wavy frizzy hair and blow dry and flat iron it twice per week. After using it once, immediately after blow drying my hair was softer, smoother, and tangle free compared to normal. I am impressed and will continue to use it as directed every 3-4 weeks.

    KU Profile picture for K18Hair UK
    K18Hair UK
    Yesterday

    So happy to hear the molecular repair technology delivered those instant results, Hilary! 🙌 Softer, smoother, and tangle-free after just one use—that's exactly what we love to see! Thanks for giving K18 a try and for sharing your experience! 💜

  • Julie S.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 55 - 64
    Hair Concern Chemical damage, Fragile/brittle hair, Dryness
    Hair Type Medium Density
    My Results Stronger Hair, Less Breakage, Visible Difference, Smoother Hair, Less Frizz
    Rated 5 out of 5 stars
    5 days ago
    Truly amazing!

    This product is exceptional for repairing dry and damaged hair, especially if you have blonde hair & receive regular highlights. I was so impressed with the results within 1 week! My hair looks fantastic and has fully recovered.

    KU Profile picture for K18Hair UK
    K18Hair UK
    4 days ago

    Thank you so much for this incredible review, Julie! 💜 We're absolutely thrilled to hear the Mini Leave-In Molecular Repair Hair Mask worked such wonders on your blonde highlights - seeing results within just 1 week is amazing! ✨ It makes our day to know your hair has fully recovered and looks fantastic. Your support means everything to us!

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