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Jumbo Leave-In Molecular Repair Hair Mask 100mL
Regular price £120
Regular price £0 Sale price £120
Jumbo leave in molecular repair hair mask
Mini, Full, and Jumbo size leave in molecular repair masks lined up next to each other on a pink background.
Grey curly hair before and after results using k18.
Red 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
K18 mask benefits
where K18 molecular repair works
the K18 routine
maximze your repair
less is more
works for all hair types
where does K18 fit into your routine?
K18 routine guide
Jumbo leave in molecular repair hair mask
Mini, Full, and Jumbo size leave in molecular repair masks lined up next to each other on a pink background.
Grey curly hair before and after results using k18.
Red 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
K18 mask benefits
where K18 molecular repair works
the K18 routine
maximze your repair
less is more
works for all hair types
where does K18 fit into your routine?
Jumbo Leave-In Molecular Repair Hair Mask 100mL
K18 routine guide
4.7
Rated 4.7 out of 5 stars
8,368 Reviews
bestseller

jumbo leave-in molecular repair hair mask

4-minute leave-in treatment - now in an exclusive jumbo size

Size:
100 mL
Regular price £120
Regular price £0 Sale price £120
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Color:
100 mL

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Jumbo leave in molecular repair hair mask

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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

    • 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.

    • 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.

    • 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.

    • 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.
    • 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.

Press + and − keys to zoom, arrow keys to pan.
Jumbo leave in molecular repair hair mask
Mini, Full, and Jumbo size leave in molecular repair masks lined up next to each other on a pink background.
Grey curly hair before and after results using k18.
Red 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
K18 mask benefits
where K18 molecular repair works
the K18 routine
maximze your repair
less is more
works for all hair types
where does K18 fit into your routine?
K18 routine guide
Jumbo leave in molecular repair hair mask
Mini, Full, and Jumbo size leave in molecular repair masks lined up next to each other on a pink background.
Grey curly hair before and after results using k18.
Red 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
K18 mask benefits
where K18 molecular repair works
the K18 routine
maximze your repair
less is more
works for all hair types
where does K18 fit into your routine?
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

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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 8,368 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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8,368 reviews
  • 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
    8 hours 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
    6 hours 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! 💕

  • Jill D.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 55 - 64
    Hair Concern Heat damage, Chemical damage, Frizz, Fragile/brittle hair
    Hair Type Thick/Coarse, Straight/Wavy
    My Results Visible Difference, Soft Touchable Hair, Less Breakage, Less Frizz, Stronger Hair
    Rated 5 out of 5 stars
    1 week ago
    Love this product!

    I have long, thick, bleached blonde hair. My best friend is a hair stylist, so I always use professional products and have always had beautiful blonde hair! However, I made the mistake of straightening it without a heat protector or leave in, because I was in a hurry one day and I literally fried my hair, because the straightener was on 450*! So I was told by my best friend to use the K18 hair repair mask, but I was hesitant because of the price of the small full size bottle. However ,I trust my hair stylist, so I purchased it. The first time using it I could feel and see a huge difference and I couldn’t believe it? I did have to use 4 pumps because of the length and thickness of my hair, but after 6 times using it in a row and after having a stem cell treatment done, my hair is back to Beautiful! I will definitely continue to incorporate this product into my weekly hair maintenance routine.

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

    Thank you so much for your review, Jill! 🤍 We're thrilled the Molecular Repair Hair Mask has helped restore your hair to beautiful after heat damage. We're so grateful for your trust and so happy you're making it part of your routine!

  • Rachel K.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Color-care, Split-Ends, Fragile/brittle hair
    Hair Type Fine/Thin, Medium Density
    My Results Visible Difference, Stronger Hair, Less Breakage, Defined Curl/Wave Pattern
    Rated 5 out of 5 stars
    1 week ago
    Essential

    As someone who dyes their hair blonde, K18 has helped it stay healthy and growing! I’m obsessed!

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

    Thank you so much for your review, Rachel! 🤍 We're thrilled the Jumbo Leave-In is helping keep your blonde hair healthy and strong. We appreciate you being part of the K18 community!

  • Yuliya B.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 45 - 54
    Hair Concern Color-care
    Hair Type Fine/Thin
    My Results Visible Difference, Less Breakage
    Rated 5 out of 5 stars
    1 week ago
    My Hair Feels So Much Healthier

    I’ve been using this hair mask for a while, and I’m really happy with the results. My hair has become more resilient and much less prone to breakage. It feels softer, smoother, and healthier, with a beautiful shine. My ends look more nourished, and my hair is much easier to brush after every use. I definitely recommend this mask, especially for damaged or color-treated hair. I’ll definitely buy it again!

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

    Thank you so much for your wonderful review! 🤍 We're thrilled to hear the Molecular Repair Hair Mask is delivering such amazing results for your hair. We truly appreciate you being part of the K18 community!

  • Kim T.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    Silky strong hair

    Recommended this by my hairdresser after colouring. She said it would strengthen my hair and she was spot on. Also feels much silkier and stronger

    Before photo in white tshirt, weaker more fragile hair. After picture in pink dress. In love with this product.

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

    Thank you so much Kim! We're thrilled your hairdresser's recommendation worked out so well. We love hearing how the Mini Leave-In Mask has strengthened and silkified your hair. Thank you for sharing your amazing results with us! 🤍

*Disclaimers

10