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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
8,479 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
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?

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
How much leave-in mask do you *really* need?
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How much leave-in mask do you *really* need?
Find your optimal dose with this easy guide.
about How much leave-in mask do you *really* need?
The Science Behind K18 Molecular Repair
/ hair science
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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molecular repair for curly + coily hair
looking to restore your natural curl pattern? you need K18.
about molecular repair for curly + coily hair
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about molecular repair for aging hair
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 8,479 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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8,479 reviews
  • Tiffany A.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 45 - 54
    Hair Concern Heat damage, Fragile/brittle hair, Dryness
    Hair Type Fine/Thin
    My Results Visible Difference, Smoother Hair, Less Frizz
    Rated 5 out of 5 stars
    2 hours ago
    Made my hair feel stronger and smoother

    I’ve been really impressed with the K18 Leave-In Molecular Repair Hair Mask. My hair is dry and prone to breakage, and after using this it felt noticeably softer, smoother, and stronger without feeling heavy or coated. It also helped with frizz and made my hair much easier to manage. A little goes a long way, and I like that it’s a leave-in treatment. I would definitely repurchase this.

    Was this helpful?
    KU Profile picture for K18Hair UK
    K18Hair UK
    50 minutes ago

    Thank you so much for the love! 💙 We're thrilled to hear the Jumbo Leave-In Molecular Repair Hair Mask is delivering the stronger, smoother results you hoped for! ✨

  • Traci K.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 55 - 64
    Hair Concern Chemical damage, Frizz, Fragile/brittle hair, Dryness
    Hair Type Fine/Thin
    My Results Less Frizz, Visible Difference, Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    2 hours ago
    So far…so good.

    I have very long, ultra-fine, color-treated hair, and after a recent full highlight my hair became extremely dry, tangled easily, and felt much more fragile than normal. I was honestly worried that it had been over-processed.

    I’ve only used K18 twice so far, but I’m already very impressed. My hair feels noticeably softer, smoother, and easier to manage, and I’m seeing less hair come out when I detangle it. The ends still need some extra moisture, but overall my hair feels healthier and much less rough than it did before I started using K18.

    I was also concerned that it might make my very fine hair greasy or weighed down, but that hasn’t happened at all. I use a small amount, let it sit for the full four minutes, and it leaves my hair feeling soft without making it flat.

    I know damaged hair doesn’t magically repair overnight, so I wasn’t expecting a miracle after one use. But after two treatments, I can already see and feel a real difference. I’m very happy with the initial results and plan to keep using it while my hair recovers from the over-processing.

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

    Thank you so much for the 5-star review, Traci! We're thrilled to hear you're already seeing such amazing results with the Mini Leave-In Molecular Repair Hair Mask. 💙 We can't wait to see how your hair continues to improve! ✨

  • Samantha P.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 35 - 44
    Hair Concern Dryness, Frizz, Split-Ends, Heat damage
    Hair Type Curly/Coily, Medium Density
    My Results Less Frizz, Bouncy Hair, Visible Difference, Stronger Hair, Smoother Hair
    Rated 5 out of 5 stars
    Yesterday
    Instant results!

    The way my hair instantly got hydrated simply after 3 pumps had me in a state of shock! And after styling, my hair was light and looking healthy!!

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

    Thank you so much for the love, Samantha! 💙 We're thrilled to hear you're getting instant results with our Full-Size Leave-In Molecular Repair Hair Mask! ✨

  • Tracey R.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 55 - 64
    Hair Concern Heat damage, Fragile/brittle hair, Dryness, Color-care, Chemical damage
    Hair Type Fine/Thin
    My Results Less Frizz, Visible Difference, Smoother Hair, Shinier Hair, Stronger Hair
    Rated 5 out of 5 stars
    2 days ago
    Repaired

    This product is the best I have ever use

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

    Thank you so much for the love! 💙 We're thrilled to hear the Mini Leave-In Molecular Repair Hair Mask is the best you've ever used! ✨

  • Vinnie T.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 65+
    Hair Concern Frizz, Dryness, Extending time between washes
    Hair Type Medium Density, Curly/Coily, Grey Hair
    My Results Less Frizz, Bouncy Hair, Visible Difference, Stronger Hair, Cleaner, fresher hair
    Rated 5 out of 5 stars
    2 days ago
    I received my first K18 from my children as a Christmas Gift

    I ran out after 7 months of use and was without it for 1 month…my hair totally suffered. I am grateful that I could afford to buy one for myself. My hair perked up immediately after the first use. Love this product. I’m 86 this month. My hair is amazing.

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

    Thank you so much for the love! 💙 We're thrilled to hear the Full-Size Leave-In Molecular Repair Hair Mask is making such a difference for your hair. You're amazing! ✨

*Disclaimers

10