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4.7
Rated 4.7 out of 5 stars
8,426 Reviews

mini 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 3-9 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
4.8
Rated 4.8 out of 5 stars
9 Reviews
Bestselling mask scented with Floating Forest biotech fragrance.
K18 molecular repair hair oil
4.8
Rated 4.8 out of 5 stars
858 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 8,426 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.
8,426 reviews
  • Danylle W.
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Chemical damage, Split-Ends, Extending time between washes, Frizz, Fragile/brittle hair
    Hair Type Fine/Thin, Straight/Wavy
    My Results Visible Difference, Soft Touchable Hair, Less Frizz, Stronger Hair, Shinier Hair
    Rated 5 out of 5 stars
    2 days ago
    I was skeptical but this stuff is a MIRACLE!

    I was recommend this by my hair stylist. I finally swallowed the price tag and bought it and I feel so dumb for not buying this sooner. I went through too many stylists who completely destroyed my hair before finding a good person and my hair needed a ton of TLC. This has brought my mushy overprocessed frizzy hair back to feeling like my virgin hair again. How!?!?! This stuff is magic! Seriously, MAGIC. My dark blonde fine hair was so overprocessed it lost all its natural shine and slight waves. This stuff brought that back in ONE treatment. Every week I can't wait for my k18 Sunday where I use their detox shampoo and put this on after. I keep it in my hair for a few days before washing again. I am in LOVE! THANK YOU!!!!

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    It's amazing how the molecular repair technology can transform your hair and restore that natural shine and texture in just one treatment. Thank you for sharing your incredible experience with us!

  • Hope L.
    Verified Buyer
    Reviewing
    K18 x Future Society Limited Edition Scent Mask
    I recommend this product
    Age 35 - 44
    Hair Concern Chemical damage, Heat damage, Fragile/brittle hair, Frizz, Dryness
    Hair Type Fine/Thin
    My Results Cleaner, fresher hair, Shinier Hair, Visible Difference, Less Breakage, Soft Touchable Hair
    Rated 5 out of 5 stars
    2 days ago
    Nothing else measures up

    This is by far THE BEST leave in mask I have ever used, I love the long lasting scent it leaves, but the most important part

    I accidentally over processed my roots and other parts of my hair I HAD to save my hair and this product surely did my hair felt amazing after just one use but now just 3 uses later im obsessed my hair is soooo soft, silky smooth and feels brand new i cannot thank this company enough for saving my hair

    Totally worth it

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    We're so thrilled to hear that the K18 x Future Society Limited Edition Scent Mask saved your hair, Hope! Thank you for sharing your experience with us!

  • TANYA G.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Frizz, Fragile/brittle hair, Dryness, Split-Ends
    Hair Type Medium Density, Straight/Wavy, Curly/Coily
    My Results Visible Difference, Smoother Hair, Soft Touchable Hair, Less Breakage, Less Frizz
    Rated 5 out of 5 stars
    3 days ago
    Wish granted!

    My ONE complaint was that this treatment didn't come in a bigger size. Now that it's double the original, I might have zero complaints about this product.

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    Thank you so much for your feedback, Tanya! We're thrilled to hear you're loving the Jumbo size – we listened to customers like you who wanted more of their favorite treatment. We appreciate you taking the time to share your experience.

  • Donna G.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    5 days ago
    Best of the best

    can't get any better hair care than with this leave in conditioner

    K Profile picture for K18Hair
    K18Hair
    5 days ago

    We feel the same way! Thank you for your review, Donna!

  • Kellie D.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Chemical damage, Fragile/brittle hair, Dryness, Split-Ends
    Hair Type Medium Density
    My Results Visible Difference, Stronger Hair, Less Breakage, Smoother Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    2 weeks ago
    Major difference

    I got a bad bleached job not too long ago and my hair was so damaged. I had to cut so much off. It made me very sad.. even after a haircut, I felt like more could have been cut off because of the damage. However, since I started using this product once a week, I have noticed significant repairing in my hair ! This is for sure, a staple product for me. I no longer waste my money on the cheap alternatives when this is the only thing on the market with its repairing technology.. !

    K Profile picture for K18Hair
    K18Hair
    2 weeks ago

    Thank you for sharing your experience, Kellie! We're absolutely thrilled that the Leave-In Molecular Repair Hair Mask has made such a significant difference in repairing your hair! It's exactly what we love to hear and we're so happy it's become a staple in your routine!

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