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4.7
Rated 4.7 out of 5 stars
7,892 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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Color-safe, non-stripping clarifying shampoo with the K18PEPTIDE™

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 7,892 reviews
7,892 reviews
  • 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
    3 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
    2 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!

  • Jorge A.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    5 days ago
    A must-have for bleached hair.

    I plan to repurchase this product and strongly recommend it to anyone who bleaches their hair, as it effectively nourishes and protects hair from damage caused by bleaching processes.

    KU Profile picture for K18Hair UK
    K18Hair UK
    5 days ago

    Thank you so much for your amazing 5-star review, Jorge! 💜 We're absolutely thrilled to hear that the Leave-In Molecular Repair Hair Mask has been such a game-changer for your bleached hair! It's wonderful that you're seeing such great results with the nourishing and protective benefits. We love that you're planning to repurchase and that you'd recommend it to others with bleached hair - that means the world to us! Thanks for taking the time to share your fantastic experience!

  • Elizabeth H.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Chemical damage, Heat damage, Dryness, Split-Ends, Fragile/brittle hair
    Hair Type Fine/Thin
    My Results Less Breakage, Soft Touchable Hair, Smoother Hair, Stronger Hair, Visible Difference
    Rated 5 out of 5 stars
    6 days ago
    Truly a miracle worker for bleached hair

    I've been able to grow my hair even longer than before, in spite of it being bleached to level 10 from level 5 brunette hair with regular root touch ups. It's now nearly reached my mid back, my goal length. If I had to only have one single pricier hair product and switch the rest of my hair routine to drugstore products, I'd be keeping the K18 mask. I've been using this product and having bleached blonde hair for the past 5 years (initially due to a hairdresser's mistake!) and now I have hair color and texture I never before imagined possible.

    KU Profile picture for K18Hair UK
    K18Hair UK
    5 days ago

    Thank you so much, Elizabeth! We're absolutely amazed to hear about your incredible hair transformation - from a hairdresser's mistake to achieving your dream hair color and texture! 💜 It's truly wonderful that the K18 mask has been such a game-changer for your bleached hair journey, helping you grow it all the way to your goal length at mid-back despite the intense processing.

    Your story is so inspiring, and we love that you'd choose K18 as your one must-have product - that means the world to us! Thank you for sharing your amazing 5-year experience and for your fantastic review!

  • Grecia A.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    Muy bueno

    Excelente

    KU Profile picture for K18Hair UK
    K18Hair UK
    1 week ago

    ¡Muchas gracias por tu reseña de 5 estrellas, Grecia! Nos emociona saber que estás teniendo una experiencia excelente con tu Leave-In Molecular Repair Hair Mask Deluxe Sample. ¡Apreciamos mucho que hayas tomado el tiempo de compartir tu opinión!

  • Marylynn C.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 65+
    Hair Concern Heat damage, Split-Ends, Frizz
    Hair Type Grey Hair, Medium Density, Straight/Wavy
    My Results Less Frizz, Visible Difference, Smoother Hair, Shinier Hair
    Rated 5 out of 5 stars
    1 week ago
    The best my grey hair has looked in a while

    I love this product for my dry mature grey hair. After the first use I noticed a difference in shine and texture. I originally ordered the travel size but like it so much that I wish I had ordered the larger size. I don't have a before photo but believe me, my hair looks much better and this photo was after the first use and before styling.

    KU Profile picture for K18Hair UK
    K18Hair UK
    1 week ago

    Thank you so much, Marylynn! We're absolutely thrilled to hear the Mini Leave-In Molecular Repair Hair Mask has made such a difference for your grey hair after just one use! The improvement in shine and texture you're experiencing is exactly what we love to hear. We totally understand wishing you'd gone with the larger size right away—that's such a great sign that it's working perfectly for your dry, mature hair! Thanks for sharing your wonderful experience and for your amazing 5-star review!

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