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4.7
Rated 4.7 out of 5 stars
7,826 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 7,826 reviews
7,826 reviews
  • Christian B.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    14 hours ago
    Holy Hair!!!

    What a difference! My hair is more vibrant and shiny! Looks so healthy!

    KU Profile picture for K18Hair UK
    K18Hair UK
    6 hours ago

    Thank you so much for this incredible review, Christian! We're absolutely thrilled to hear that our Leave-In Molecular Repair Hair Mask made such a dramatic difference for you! It's amazing that you're seeing that vibrant, shiny, healthy-looking hair - that's exactly what we hoped to achieve with our molecular repair technology! Your excitement about the transformation truly means the world to us, and we're so grateful to have you as part of our K18 community!

  • Lia T.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Fragile/brittle hair
    Hair Type Fine/Thin
    My Results Less Frizz, Stronger Hair, Smoother Hair
    Rated 5 out of 5 stars
    2 days ago
    The best

    I truly feel the difference, I loved it!

    KU Profile picture for K18Hair UK
    K18Hair UK
    7 hours ago

    Thank you so much for this wonderful review, Lia! We're absolutely thrilled to hear that you can truly feel the difference our Mini Leave-In Molecular Repair Hair Mask is making for your hair! It's amazing that you loved it so much - your feedback about experiencing real, noticeable results means the world to us. We're so grateful to have you as part of our K18 community and that you're loving the molecular repair benefits in this convenient mini size!

  • Tara W.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 45 - 54
    Hair Concern Chemical damage, Heat damage, Frizz, Fragile/brittle hair, Dryness
    Hair Type Medium Density
    My Results Less Frizz, Bouncy Hair, Visible Difference, Defined Curl/Wave Pattern, Shinier Hair
    Rated 5 out of 5 stars
    1 week ago
    Four washes in and I am a believer

    I saw a difference from the first wash and now that I am four washes in my hair has a lot of its bounce. Back in the curls are holding much much better. Excited to continue using K28!

    KU Profile picture for K18Hair UK
    K18Hair UK
    9 hours ago

    Thank you so much for this amazing review, Tara! We're absolutely thrilled to hear that you saw a difference from the very first wash and that after just four uses, your hair is already regaining so much of its bounce and curl definition! It's incredible that your curls are holding much better - that's exactly the kind of molecular repair results we hoped to achieve with this leave-in treatment. Your excitement about continuing with K18 truly means the world to us, and we're so grateful to have you as part of our community! We can't wait to hear how your hair continues to transform with regular use!

  • Ariana S.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 25 - 34
    Hair Concern Split-Ends
    Hair Type Fine/Thin
    My Results Cleaner, fresher hair, Stronger Hair, Less Breakage
    Rated 5 out of 5 stars
    1 week ago
    Best my hair has felt

    Iv been dying my hair for 15+ years and have always had issues with damage. Was recommend by my hairstylist after use in an appointment and followed up with the mask for the next 4 washes. My hair has never felt better and Iv had significantly less split ends

    KU Profile picture for K18Hair UK
    K18Hair UK
    11 hours ago

    Thank you so much for this incredible review, Ariana! We're absolutely thrilled to hear that after 15+ years of coloring your hair, you're finally experiencing the best hair condition you've ever had with our Mini Leave-In Molecular Repair Hair Mask! It's wonderful that your hairstylist recommended it and that you followed through with the treatment - seeing such dramatic improvement in damage repair and significantly fewer split ends after just 4 washes is exactly what we hoped to achieve with our molecular repair technology! Your feedback about how it's transformed your hair after dealing with damage for so many years truly means the world to us, and we're so grateful to have you as part of our K18 community!

  • Sofia K.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    No more frizzy hair

    I started using K18 about 3 weeks ago and I am super pleased with the results. With highlights, monthly root color and naturally curly hair it has become nearly impossible to control my frizzy hair. But I am astonished at the results. My hair doesn’t look like dry straw anymore. I am willing to pay the right price for a product that will make my hair look healthier and beautiful. I definitely recommend K18.

    KU Profile picture for K18Hair UK
    K18Hair UK
    11 hours ago

    Thank you so much for this incredible review, Sofia! We're absolutely thrilled to hear that after just 3 weeks of using K18, you've seen such amazing transformation in your hair's texture and manageability! It's wonderful that you're no longer dealing with that dry, straw-like feeling - especially with all the processing your hair goes through with highlights and monthly root color. We completely understand how challenging it can be to manage naturally curly hair that's been chemically treated, so your feedback about how our molecular repair technology is helping control that frizz and restore your hair's health truly means the world to us! We're so grateful that you're seeing the value in investing in healthier, more beautiful hair, and we're honored to have you as part of our K18 community!

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