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Full-Size Leave-In Molecular Repair Hair Mask 50mL
Regular price $75
Regular price $0 Sale price $75
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Leave-in molecular repair hair mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Red curly hair before and after results using k18.
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
Full-Size Leave-In Molecular Repair Hair Mask 50mL
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
works for all hair types
where does K18 fit into your routine?
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
Red curly hair before and after results using k18.
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
Full-Size Leave-In Molecular Repair Hair Mask 50mL
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
works for all hair types
where does K18 fit into your routine?
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
9,098 Reviews
bestseller

full-size leave-in molecular repair hair mask

4-minute leave-in treatment to reverse hair damage

Size:
50mL
Regular price $75
Regular price $0 Sale price $75
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Color:
50mL

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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 (K18PEPTIDE™), Hydrolyzed Wheat Protein, Hydrolyzed Wheat Starch, Isopropyl Alcohol, Tocopherol, Phenoxyethanol, Potassium Sorbate, Citric Acid, Fragrance (Parfum), Geraniol, Linalool, Hexyl Cinnamal, Benzyl Alcohol.

    • 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
K18 x Future Society leave-in molecular hair mask
Join Waitlist
K18 molecular repair hair oil
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Leave-in molecular repair hair mask 50mL
Full-Size Leave-In Molecular Repair Hair Mask 50mL
Red curly hair before and after results using k18.
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
Full-Size Leave-In Molecular Repair Hair Mask 50mL
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
works for all hair types
where does K18 fit into your routine?
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
Red curly hair before and after results using k18.
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
Full-Size Leave-In Molecular Repair Hair Mask 50mL
the K18 routine
Full-Size Leave-In Molecular Repair Hair Mask 50mL
less is more
works for all hair types
where does K18 fit into your routine?
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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The Science Behind K18 Molecular Repair
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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 9,098 reviews
93%would recommend these products
Reviews Summary
Customers say this leave-in hair mask transforms their hair texture and manageability after just one use. Many reviews mention noticeable improvements in softness and reduced frizz. Users with curly, fine, and color-treated hair report positive results. The mask works well for various hair types, with many noting improved texture and easier styling. While some mention the product's high price point, most find a little goes a long way. A few users recommend using conditioner alongside the mask for best results. Reviews consistently highlight the mask's effectiveness for addressing dry, brittle hair concerns.
Customers Talked About
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9,098 reviews
  • Jana G.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Frizz, Dryness, Color-care, Split-Ends
    Hair Type Medium Density, Curly/Coily
    My Results Defined Curl/Wave Pattern, Smoother Hair, Soft Touchable Hair, Visible Difference, Bouncy Hair
    Rated 5 out of 5 stars
    6 days ago
    Unbeatable

    I have not been able to find a product that does anything remotely close to this. Repairs damage and just brings my curls back to life. Pics are before, after one use, then after 2 uses and it just keeps getting better. Plus I touch my hair all day and it’s lightweight and not sticky.

    Was this helpful?
    K Profile picture for K18Hair
    K18Hair
    6 days ago

    Thank you so much for your amazing review, Jana! We're absolutely thrilled to hear that the Jumbo Leave-In Molecular Repair Hair Mask has brought your curls back to life and that you're seeing such incredible progress with each use. It means the world to us to know that you haven't found anything else that compares to our formula for repairing damage. We love that it's lightweight and not sticky while still giving you those touchable, beautiful results. Thank you for taking the time to share your experience—we're so grateful to have you as part of the K18 community!

  • Renee H.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 45 - 54
    Hair Concern Chemical damage, Frizz, Fragile/brittle hair, Dryness, Split-Ends
    Hair Type Fine/Thin
    My Results Less Frizz, Visible Difference, Smoother Hair, Shinier Hair
    Rated 5 out of 5 stars
    1 week ago
    Awesome product

    This product is a saving grace! After having a hair dresser have a tantrum and poured acid all over my hair and scalp K 18 has definitely helped! Great company and will continue to buy the products!

    Was this helpful?
    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you so much, Renee! 💛 We're so sorry about your experience, but thrilled K18 has been able to help restore your hair. Your trust means everything to us! ✨

  • kelly b.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Deluxe Sample
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    Great product!

    Wish it was easier to get out of the sample but otherwise great product

    Was this helpful?
    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you so much for the 5 stars, Kelly! We're thrilled you love the Leave-In Molecular Repair Hair Mask and appreciate your feedback about the sample packaging.

  • Julia T.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Heat damage, Fragile/brittle hair, Split-Ends, Oily hair/scalp
    Hair Type Fine/Thin
    My Results Visible Difference, Stronger Hair, Less Breakage
    Rated 5 out of 5 stars
    1 week ago
    Absolutely favorite

    I bought my first bottle at HongKong Sephora back in March. I wasn’t sure how good it’s gonna be since I was recommended by AI. I have thin/fine hair, and I bleach it to blonde every 3 months. I always had a hard time growing my hair long cause it’s so damaged. Nothing I tried worked!!!! Not even the products recommended by my hairstylist.

    Was this helpful?
    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you so much, Julia! 💛 We're thrilled the Jumbo Leave-In helped where nothing else worked for your bleached hair. Your trust means everything to us! ✨

  • Shannon B.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Chemical damage, Heat damage, Frizz, Fragile/brittle hair, Dryness
    Hair Type Fine/Thin
    My Results Less Breakage
    Rated 5 out of 5 stars
    1 week ago
    It worked

    It seems to have made a difference in breakage

    Was this helpful?
    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you for your wonderful review, Shannon! We're so thrilled to hear that the Jumbo Leave-In Molecular Repair Hair Mask is making a real difference in reducing breakage for you. That's exactly what we love to see - our molecular repair technology working to strengthen and protect your hair from the inside out.

    It's so rewarding to know that K18 is helping improve the health of your hair. Thank you for choosing us and for taking the time to share your experience!

*Disclaimers

10