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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
8,645 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
Clarify. for less frequent heavy duty washing. just one wash removes 99% of product buildup*, 95% of sebum*, and 76% of copper*. Formulated with K18PEPTIDE™. PEPTIDE PREP™ detox shampoo 8.5 oz
PEPTIDE PREP™ detox shampoo
FutureIQ™ biomimetic hair longevity serum
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?

still have questions? visit our help center

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
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The Top K18 Mask FAQs
answering your most-asked questions.
about The Top K18 Mask FAQs
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looking to restore your natural curl pattern? you need K18.
about molecular repair for curly + coily hair
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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 8,645 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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8,645 reviews
  • Sooji R.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 55 - 64
    Hair Concern Color-care, Frizz
    Hair Type Grey Hair, Thick/Coarse
    My Results Visible Difference, Smoother Hair, Less Frizz
    Rated 5 out of 5 stars
    4 minutes ago
    Smooth!

    Smooth hair if you follow directions. Hoping it repairs more over time. Promising!

    Was this helpful?
  • Angela W.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Rated 5 out of 5 stars
    7 hours ago
    Amazing product

    At first I thought this isn’t going to work. I can’t wash my hair and not use conditioner! I put the product in towel dried hair waited 4 min and blow dried. Seemed ok no sticky mess styled ok but didn’t notice much difference I did this for 3 washes and didn’t really see much of a change. But on the 4 wash ….. OMG my hair was amazing I was able to wash my hair and brush without conditioner, Super soft and frizz and tangle free !!! I purchased the oil as well. The pair together are amazing !!!!

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    6 hours ago

    Thank you so much for the amazing 5-star review, Angela! 💗 We're thrilled to hear that the Mini Leave-In Molecular Repair Hair Mask has made such a difference for your hair! It's wonderful that you stuck with it and discovered how amazing your results could be - super soft, frizz and tangle free hair is exactly what we love to hear! ✨ And we're so glad the pair with the oil is working beautifully together for you. Thanks for sharing the K18 love! 💗

  • Brenda
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Rated 4 out of 5 stars
    13 hours ago
    4 Stars

    expensive but hoping it gives results to my fine breakage hair.

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    9 hours ago

    Thank you for sharing your feedback! We understand that investing in hair care can feel like a big commitment, and we hope our Molecular Repair Mask helps strengthen your hair and improve the appearance of breakage over time. We appreciate you giving it a try and hope you love the results! 💛

  • Sophia M.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 18 - 24
    Hair Concern Chemical damage, Split-Ends, Fragile/brittle hair
    Hair Type Fine/Thin
    My Results Visible Difference, Stronger Hair, Less Frizz, Smoother Hair, Less Breakage
    Rated 5 out of 5 stars
    16 hours ago
    Only thing that actually works

    I absolutely love this product! I have naturally very dark brown hair and spent a year bleaching it every six weeks. This is the only product that has truly helped my hair recover, become healthier, and grow. I’ve noticed such a difference, and I couldn’t be happier with the results! My mom has started using it too, and she loves it just as much as I do!

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    14 hours ago

    Thank you so much for the amazing review, Sophia! 💕 We're thrilled the Molecular Repair Hair Mask is helping your hair recover and grow. So happy your mom loves it too! ✨

  • Melody O.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 65+
    Hair Concern Chemical damage, Frizz, Heat damage, Color-care, Fragile/brittle hair
    Hair Type Grey Hair, Curly/Coily, Fine/Thin
    My Results Less Frizz, Stronger Hair, Visible Difference, Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    Yesterday
    Love it so far

    Hoping it to help me with frizzy, dry hair

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    Yesterday

    Thank you so much, Melody! 💗 We're thrilled to hear you're loving the Mini Leave-In Molecular Repair Hair Mask so far! We hope it continues to work wonders for your hair. ✨

*Disclaimers

10