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Full-Size Leave-In Molecular Repair Hair Mask 50mL
Regular price £70
Regular price £0 Sale price £70
Full-Size 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
Full-Size 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
8,779 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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Full-Size 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.
Full-Size 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
Full-Size 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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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 8,779 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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8,779 reviews
  • Michael S.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Heat damage, Fragile/brittle hair, Split-Ends
    Hair Type Medium Density
    My Results Less Frizz, Visible Difference, Stronger Hair, Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    9 hours ago
    MAGIC RESTORATION! ✨

    I recently had my hair bleached, and my ends and lighter blonde sections were left terribly damaged. This product restored my damaged hair in just ONE DAY!

    I’m honestly so amazed. It feels like magic!!!

    My hair was stretchy like chewing gum, tangled, and had broken ends.

    And after just ONE use… WOW! Everything improved so much!

    Honestly, this product is THE BEST! 🤍

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

    Thank you so much for your amazing review, Michael! We're thrilled the Molecular Repair Hair Mask delivered such incredible results for your bleached hair. Your support means everything to us! 💖✨

  • Nicole W.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 45 - 54
    Hair Concern Color-care, Fragile/brittle hair, Dryness
    Hair Type Medium Density, Straight/Wavy, Fine/Thin
    My Results Visible Difference, Stronger Hair, Less Breakage, Smoother Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    10 hours ago
    Leave in Molecular Repair Mask

    This product is amazing! My hair feels so soft, tangle free and healthy. It's my favorite weekly ritual.

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

    Thank you so much for your amazing 5-star review, Nicole! We're thrilled to hear that our Mini Leave-In Molecular Repair Mask has become your favorite weekly ritual. Your support means everything to us! 💙

  • Jon S.
    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 Thick/Coarse
    My Results Less Frizz, Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    10 hours ago
    The best hair mask out there

    Love the K18 hair mask. I have been using it for several years and won’t go without it.

    Love the jumbo size. Value is good.

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

    Thank you so much for your amazing 5-star review, Jon! 💖 We're thrilled you've been loving our Jumbo Leave-In Molecular Repair Hair Mask for years. Your loyalty means everything to us!

  • Cheryl B.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Rated 5 out of 5 stars
    16 hours ago
    Amazing Product

    Absolutely amazing product. I never skip using this the best product on the market.

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

    Thank you so much for your 5-star review, Cheryl! 💖 We're thrilled to hear you love our Jumbo Leave-In Molecular Repair Hair Mask and that it's become such an essential part of your routine! ✨

  • Cheryl B.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    16 hours ago
    Amazing Product

    Absolutely amazing product it has transformed my hair

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

    Thank you so much for your wonderful review, Cheryl! 💖 We're thrilled to hear that our Leave-In Molecular Repair Hair Mask has transformed your hair. Your support means the world to us! ✨

*Disclaimers

10