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Leave-In Molecular Repair Hair Mask 5mL
4.7
Rated 4.7 out of 5 stars
8,136 Reviews

leave-in molecular repair hair mask

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

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Description

A leave-in treatment mask for all hair types that clinically reverses damage in 4 minutes. The patented peptide technology works to repair damage from bleach, color, chemical services & heat – restoring strength, softness, smoothness, and bounce to hair.

Repairs Damage Caused By

  • Bleach + Color
  • Heat
  • Chemical Services

IN the shower

  1. Shampoo, do not condition.

OUT of the shower

  1. Towel dry thoroughly.
  2. Begin with 1 pump of the K18 Mask and add more as needed depending on the length, thickness, and condition.
  3. Work evenly into hair from ends to roots, one pump at a time.
  4. Let sit for 4 minutes to activate.
  5. Do NOT rinse out.
  6. Style as usual.

creates hair like new

Traveling deeper into the inner layers of hair than traditional repair products, our revolutionary patented K18Peptide™ is just the right size and makeup to fit in and reconnect broken keratin chains, renewing hair with strength, softness, smoothness, and bounce. You can feel and see the difference with the first use.

Start by using K18 after the first 4-6 washes. Then switch to maintenance mode for a boost of renewed strength, softness, smoothness, and bounce when needed.

  • DO use a clarifying shampoo if you’re a heavy product or dry shampoo user to remove buildup and help our peptide penetrate and get where it needs to go.
  • DO wait the full 4 minutes before styling or applying other product
  • DO use every 4-6 shampoos consecutively to see and feel ongoing results
  • DON’T condition your hair before application (trust us, most won’t need it after K18, if you still need, add a leave-in after the 4-minute window is up post-application)
  • DON’T overuse, a little goes a long way.
  • DON’T rinse out. This is a leave-in, so you know, leave it in!

Our K18Peptide™ is clinically proven to reverse damage in just 4 minutes.

  • Heals damage from bleach, color, chemical services, and heat
  • Restores strength, softness, smoothness, and bounce
  • Doesn’t wash away with shampoo, leaving lasting results
  • Vegan, color-safe, cruelty-free

up to 91% original strength*
up to 94% original elasticity*

* Results observed in a clinical study while using mist and mask as part of a bleaching treatment. Results may vary depending on hair type, quality and history.

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.

Description

A leave-in treatment mask for all hair types that clinically reverses damage in 4 minutes. The patented peptide technology works to repair damage from bleach, color, chemical services & heat – restoring strength, softness, smoothness, and bounce to hair.

what you can expect
by damage type

backed by science,
loved by stylists
Our community of stylists and colorists believe K18 is liberating hair—no matter the hair type or generation.
“K18 allows me to go everywhere I want to go with my color work and the end result is my guests get to be bright and shiny and healthy.”

– Christine Thompson, Director of Color at Spoke & Weal
got questions?
Get started here
When hair gets damaged, the polypeptide chains (keratin chains) that make up the inner structure of hair strands become weakened and break. For context, there are billions and billions of polypeptide chains (keratin chains) in a single strand of hair. When these are damaged, hair’s core structure responsible for elasticity and strength becomes compromised and as a result it loses its resiliency and shine—or the look and feel of healthy hair.

After spending a decade in the lab scanning and testing all amino acid sequences across the entire keratin genome that makes up human hair searching for a breakthrough, we discovered one unique sequence (a bioactive peptide) that brings damaged hair back to its original, youthful state. This is our K18Peptide™.

Traveling deeper into the inner layers of hair than traditional repair products, our revolutionary peptide is just the right size and makeup to fit in and reconnect those broken polypeptide chains (keratin chains). And because our peptide is a bit of an overachiever, as a result of this reconnection, any disturbed disulfide bonds are also re-conformed.

Our peptideemploys biomimetics to get the job done. To put it simply: Biomimetics is the practice of learning from and mimicking nature. Mimicking the natural structure of keratin building blocks (amino acid sequences), our K18 bioactive peptide is recognized as natural by the hair. It’s not washed away by water or shampoo like traditional bonding agents either, making K18 a genuine, lasting solution for damaged strands.
Our patented peptide is a unique sequence of amino acids that travels deep into hair’s core structure to fit in and reconnect broken polypeptide chains (keratin chains) responsible for hair strength and elasticity.

An Analogy: When building proteins, the order of the amino acids determines the kind of protein and its properties, much like the way letters are arranged to make meaningful words and sentences. In the same way the order and where each word sits in a sentence leads to its overall meaning, K18 is the magic word that fits right in, integrating itself with the keratin chains as the hair recognizes it as a natural building block.
K18 is most effective on clean, towel-dried hair. Conditioners use silicones and conditioning agents that form heavy coatings on hair , preventing our peptide from reaching the broken polypeptide chains deep inside hair’s inner layer.
We like to keep our formulas minimal, only using the exact amount of ingredients needed to get the peptide where it needs to go. Our unique blend of 3 alcohols function to open up the hair cuticle so the K18Peptide ™ can penetrate the inner most layer of hair, reaching the broken polypeptide chains (keratinchains). Here the alcohol serves as an agent to optimize the hair environment for K18 to work on a deeper level.
You will start to see stronger, softer, healthier hair after just one use.

Renews strength, softness, smoothness, and bounce

K18 strengthens hair’s core structure, restoring damaged curl patterns and leaving strands looking and feeling like new.
K18 reconnects broken keratin chains, restoring hairs elasticity and strength meaning coily hair can be renewed and brought back to its original springy, healthy shape.
K18 restores strength, softness, smoothness, and bounce so even the sleekest hair can feel like new.
4.7
Rated 4.7 out of 5 stars
Based on 8,136 reviews
8,136 reviews
  • Megan L.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 45 - 54
    Hair Concern Frizz
    Hair Type Fine/Thin
    My Results Less Frizz, Shinier Hair, Smoother Hair
    Rated 5 out of 5 stars
    3 days ago
    Love it

    Leaves hair so soft and smooth,dry time is much less.

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    Thank you for your review! We love a shorter hair care routine!

  • Arnell M.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 55 - 64
    Hair Concern Chemical damage, Fragile/brittle hair, Dryness, Split-Ends
    Hair Type Fine/Thin, Straight/Wavy, Curly/Coily, Grey Hair
    My Results Visible Difference, Smoother Hair, Stronger Hair, Soft Touchable Hair, Defined Curl/Wave Pattern
    Rated 5 out of 5 stars
    4 days ago
    Amazing products!!

    My hair has been a mess for years. I have tried so many products only to have the results wash away with my next shampoo! My new hair stylist recommended K18! I started with Peptide Prep shampoo and Leave in Hair Mask. My hair looks and feels amazing with lasting results!! I have ordered the full line now and highly recommended these products!!

    K Profile picture for K18Hair
    K18Hair
    4 days ago

    What an amazing stylist! Thank you for your review!

  • Angelo A.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 55 - 64
    Hair Concern Chemical damage, Dryness, Fragile/brittle hair
    Hair Type Fine/Thin
    My Results Less Frizz, Smoother Hair, Less Breakage, Visible Difference, Stronger Hair
    Rated 5 out of 5 stars
    1 week ago
    Big difference

    Hair was so dry and like straw before using, and it is now so much softer, silkier and smoother.

    K Profile picture for K18Hair
    K18Hair
    5 days ago

    Healthy soft hair is a must! Thank you Angelo!

  • Kaitlyn S.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Heat damage, Color-care, Frizz, Dryness, Split-Ends
    Hair Type Fine/Thin
    My Results Visible Difference, Stronger Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    1 week ago
    I was so happy to finally splurge on the jumbo size

    It helps when used as directed and saveds me some time as I dont have to deep condition . No complaints although it's hard to tell how "bad" or "good" my hair is. I am coming back from the sample to buy the astro lift tho it seems to really give some umph!

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you for your review!

  • Karen M.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 35 - 44
    Hair Concern Dryness, Split-Ends, Fragile/brittle hair, Chemical damage, Heat damage
    Hair Type Fine/Thin
    My Results Visible Difference, Less Frizz, Less Breakage, Stronger Hair, Smoother Hair
    Rated 5 out of 5 stars
    2 weeks ago
    Love it

    My hair is extremely thin and fine and has tons of damage and breakage. My ends were like straw. I decided to try this based on Abby's recommendation from YouTube. I used it 4 times in a row and now use it once a week. I do think I'm seeing results as my ends are looking better. It's expensive but a little goes a long way and while it's still a little early, I'd say it's worth it. Before and after pic included.

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you Karen! Yes less is more!

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