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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
tilebestseller | color:black
4.7
Rated 4.7 out of 5 stars
8,601 Reviews

full-size leave-in molecular repair hair mask

4-minute leave-in treatment to reverse hair damage
OR

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
  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.
  • 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.

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.

  • 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.

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.

pairs well with
limited edition
new
K18 x Future Society leave-in molecular hair mask
4.9
Rated 4.9 out of 5 stars
43 Reviews
Bestselling mask scented with Floating Forest biotech fragrance
K18 molecular repair hair oil
4.8
Rated 4.8 out of 5 stars
932 Reviews
Weightless oil that strengthens, repairs damage + reduces frizz

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

got questions?
Get started here.
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.
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
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.
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).
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.

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.

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
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 8,601 reviews
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.
8,601 reviews
  • Yessi S.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Heat damage, Chemical damage, Color-care, Fragile/brittle hair, Extending time between washes
    Hair Type Medium Density, Curly/Coily
    My Results Bouncy Hair, Visible Difference, Stronger Hair, Defined Curl/Wave Pattern, Less Breakage
    Rated 5 out of 5 stars
    5 minutes ago
    This is the best Repair Hair Mask of the whole world!

    When I dyed my hair, I thought I would lose my curls, but thanks to this mask I can enjoy my new look and my curls!

  • S J.
    Verified Reviewer
    Reviewing
    K18 x Future Society Limited Edition Scent Mask
    I recommend this product
    Age 65+
    Hair Concern Extending time between washes
    Hair Type Fine/Thin, Grey Hair
    My Results Smoother Hair, Visible Difference, Stronger Hair
    Rated 5 out of 5 stars
    9 hours ago
    Magical

    I am in the senior age group. This makes my hair look healthy again. I use one pump every time I wash my hair. I am also am using the k 18 shampoos. I definitely recommend thus product at least for my age group.

    K Profile picture for K18Hair
    K18Hair
    9 hours ago

    Thank you so much for your incredible review, S! We're absolutely thrilled to hear that our K18 x Future Society Limited Edition Scent Mask is making your hair look healthy again - there's no better compliment than knowing our molecular repair technology is delivering such magical results for you with just one pump each wash! ❤️

  • Leslie F.
    Verified Buyer
    Reviewing
    K18 x Future Society Limited Edition Scent Mask
    I recommend this product
    Age 35 - 44
    Hair Concern Chemical damage, Heat damage, Split-Ends
    Hair Type Fine/Thin
    My Results Visible Difference, Stronger Hair, Smoother Hair, Shinier Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    3 days ago
    Wowzer!

    This stuff works! Price point is higher than anything I’ve ever paid for a hair product, but man does it work! Noticed a difference in the way my hair shined and felt on about the third wash! I use a couple of times after getting my hair colored to keep it protected.

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    Thank you so much for your incredible review, Leslie! We're absolutely thrilled to hear that our K18 x Future Society Limited Edition Scent Mask is delivering such amazing results for you - there's no better compliment than knowing our molecular repair technology is making your hair shine and feel so much better, especially when you're using it to protect your color-treated hair! ❤️

  • Megan C.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Frizz, Fragile/brittle hair, Dryness, Oily hair/scalp
    Hair Type Fine/Thin
    My Results Less Frizz, Visible Difference, Shinier Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    4 days ago
    Fixes my hair everytime

    I started using this product a few weeks ago and it makes my hair that desperately needs a haircut look so refreshed and healthy. I followed the instructions to use for a few times in a row then as needed and I’ve definitely noticed a difference. Can’t recommend enough

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    Thank you so much for your incredible review, Megan! We're absolutely thrilled to hear that our Jumbo Leave-In Molecular Repair Hair Mask is making your hair look so refreshed and healthy - there's no better compliment than knowing our molecular repair technology is working its magic to transform your hair, especially when you're following the instructions and seeing such amazing results! ❤️

  • Vanessa C.
    Verified Buyer
    Reviewing
    K18 x Future Society Limited Edition Scent Mask
    I recommend this product
    Age 35 - 44
    Hair Concern Chemical damage, Heat damage, Frizz, Fragile/brittle hair, Oily hair/scalp
    Hair Type Fine/Thin, Straight/Wavy
    My Results Less Frizz, Visible Difference, Soft Touchable Hair, Shinier Hair, Smoother Hair
    Rated 5 out of 5 stars
    1 week ago
    Love this product!!

    This product really is a game changer. If you use bleach on your hair u need the K 18 molecular repair mask!

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you so much for your incredible review, Vanessa! We're absolutely thrilled to hear that our K18 x Future Society Limited Edition Scent Mask is a game changer for you - there's no better compliment than knowing our molecular repair technology is working miracles on bleached hair! ❤️

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