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Full-Size Leave-In Molecular Repair Hair Mask 50mL
Regular price £70
Regular price £0 Sale price £70
Leave-in molecular repair hair mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
Grey curly hair before and after results using k18.
Bleach blonde hair before and after results using k18.
Red curly hair before and after results using k18.
get stronger, more resilient hair. left - 8x bleach without K18, right 8x bleach with K18
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
works for all hair types
where does K18 fit into your routine?
Mini versus full size product comparison
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
K18 routine guide
Leave-in molecular repair hair mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
Grey curly hair before and after results using k18.
Bleach blonde hair before and after results using k18.
Red curly hair before and after results using k18.
get stronger, more resilient hair. left - 8x bleach without K18, right 8x bleach with K18
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
works for all hair types
where does K18 fit into your routine?
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Mini versus full size product comparison
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
K18 routine guide
4.7
Rated 4.7 out of 5 stars
8,397 Reviews
bestseller

full-size leave-in molecular repair hair mask

4-minute leave-in treatment to reverse hair damage

Size:
50 mL
Regular price £70
Regular price £0 Sale price £70
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Color:
50 mL

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Leave-in molecular repair hair mask 50mL

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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

Repairs Damage Caused By

Bleach + Color

Heat

Chemical Services

    • ingredients

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

    • dos and don'ts
      • 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.
    • key benefits

      **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.

    • more to know

      - **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.

    • how to use

      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.

pairs well with
PEPTIDE PREP™ detox shampoo
Molecular repair hair oil
Press + and − keys to zoom, arrow keys to pan.
Leave-in molecular repair hair mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
Grey curly hair before and after results using k18.
Bleach blonde hair before and after results using k18.
Red curly hair before and after results using k18.
get stronger, more resilient hair. left - 8x bleach without K18, right 8x bleach with K18
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
works for all hair types
where does K18 fit into your routine?
Mini versus full size product comparison
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
K18 routine guide
Leave-in molecular repair hair mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
Grey curly hair before and after results using k18.
Bleach blonde hair before and after results using k18.
Red curly hair before and after results using k18.
get stronger, more resilient hair. left - 8x bleach without K18, right 8x bleach with K18
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
works for all hair types
where does K18 fit into your routine?
Mini versus full size product comparison
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
K18 routine guide
got questions?

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.

soft, strong, bouncy hair for everyone

Repair damage for hair like new* in 4 minutes.

before afer
before
after
"I absolutely love this product!! You have to see it to believe it!"
- Christina Marie P.
before afer
before
after
“…I had my hair chopped (it was begging for it) along with some highlights and coloring of the roots. My hair stylist used this on my hair and I absolutely loved how it made my hair feel ... I love this mask so much!”
- Ashley P.
before afer
before
after
"Amazing the way it feels and the shine provides to the hair instantly."
- Sandra M.
before afer
before
after
"I’ve been using this mask for about four washes so far. I feel that my hair is getting healthier."
- Olga S.
before afer
before
after
"It makes my hair so soft and weightless, I absolutely love it... Makes my hair feel so luxurious, it’s like I just left the salon. Can’t recommend this product more!"
- Anastasiia T.
before afer
before
after
"My hair has been a mess for years... My new hair stylist recommended K18! ... My hair looks and feels amazing with lasting results!!"
- Arnell M
before afer
before
after
"I have heat damaged color treated curly hair and this has improved my hair health immensely...This is one of those products that has incorporated itself into my routine for the rest of my life..."
- Siria A.
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.

Explore the Science EXPLORE THE SCIENCE
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.


*k18hair.com/disclaimers

learn more on our blog
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Find your optimal dose with this easy guide.
about How much leave-in mask do you *really* need?
The Science Behind K18 Molecular Repair
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The Science Behind K18 Molecular Repair
See how our K18PEPTIDE™-powered mask reverses damage in 4 minutes for lasting...
about The Science Behind K18 Molecular Repair
The Top K18 Mask FAQs
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The Top K18 Mask FAQs
answering your most-asked questions.
about The Top K18 Mask FAQs
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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 8,397 reviews
93%would recommend these products
Reviews Summary
Customers say this hair mask transforms damaged, bleached, and chemically-treated hair, making it softer, stronger, and more manageable. Many report significant improvements in hair texture, with reduced breakage, split ends, and frizz. Users with curly hair find it enhances curl definition and reduces dryness. The lightweight formula doesn't weigh hair down or leave residue. Many reviews mention it works particularly well for bleached hair, helping restore smoothness and shine. Some note the price is high but find it worthwhile since only small amounts are needed per use.
Customers Talked About
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8,397 reviews
  • Hazzel J.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 18 - 24
    Hair Concern Chemical damage, Color-care, Frizz, Dryness, Split-Ends
    Hair Type Thick/Coarse
    My Results Less Frizz, Bouncy Hair, Visible Difference, Stronger Hair, Smoother Hair
    Rated 5 out of 5 stars
    2 days ago
    Amazing for bleached hair

    I absolutely love this product! My hairdresser recommended it to me, and I’m so glad I tried it. My hair is bleached and has been through a lot of processing, and K18 is honestly the only product I’ve tried that has made a noticeable difference. My hair feels so much healthier, softer, and more manageable after using it. A little goes a long way, too. Definitely worth it for damaged or bleached hair. I’ll absolutely keep using this! ❤️

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    2 days ago

    We're so thrilled your hairdresser recommended us! 💕 We love hearing that the Molecular Repair Mask is making such a noticeable difference for your bleached hair. Thank you for the love! ✨

  • Sophie M.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Rated 5 out of 5 stars
    3 days ago
    Before and after so happy!

    I have been using K18 for a few months now mainly on my front pieces and the condition of them has improved dramatically! Here are some before and after photos

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    2 days ago

    Thank you so much Sophie! We love your 5-star review and we're thrilled to hear that the Mini Leave-In Molecular Repair Hair Mask has made such a dramatic difference for your front pieces over these past few months! 💕 Before and after photos are the best, and we're so happy you're seeing such amazing results with K18. Thank you for sharing your experience with us! ✨

  • Kirsty R.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    3 days ago
    Amazing

    This product has saved my hair, it truly is amazing for bleached hair. My hair feels and looks great. Would definitely recommend.

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    3 days ago

    Thank you so much Kirsty for your wonderful review! We're thrilled the Leave-In Molecular Repair Hair Mask has made such a difference for your bleached hair. Your kind words mean everything to us!

  • Katie A.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Fragile/brittle hair, Dryness
    Hair Type Medium Density
    My Results Less Breakage, Visible Difference, Bouncy Hair, Stronger Hair, Smoother Hair
    Rated 5 out of 5 stars
    5 days ago
    Totally worth it!

    The K18 Mask is absolutely transforming! I absolutely prise myself with my hair and all of a sudden it started becoming dry and broke easily. I bought many products including Kerastase and Oribe. K18 is by far the only product that significantly changed the quality of my hair. This product is a game changer!

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    5 days ago

    Thank you so much for sharing, Katie! 🤍 We're thrilled the Jumbo Leave-In Molecular Repair Hair Mask has made such a transformative difference for your hair. We truly appreciate you being part of the K18 community!

  • Rocio R. U.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Dryness, Split-Ends, Fragile/brittle hair, Extending time between washes
    Hair Type Medium Density
    My Results Less Frizz, Visible Difference, Stronger Hair, Less Breakage, Shinier Hair
    Rated 5 out of 5 stars
    1 week ago
    It works wonders

    I relax my hair so it is pretty damaged, I have used this 3 times and I already feel a difference. My hair feels stronger, it leaves your hair shiny and soft.

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    1 week ago

    Thank you so much for sharing, Rocio! We're thrilled to hear the Molecular Repair Hair Mask is making such a positive difference for your hair. We love knowing it's leaving your strands feeling stronger, shinier, and softer! 💕

*Disclaimers

10