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Leave-In Molecular Repair Hair Mask 5mL
4.7
Rated 4.7 out of 5 stars
9,003 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?
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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 9,003 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
9,003 reviews
  • Heather H.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 25 - 34
    Hair Concern Heat damage, Chemical damage, Fragile/brittle hair, Dryness, Split-Ends
    Hair Type Thick/Coarse, Curly/Coily
    My Results Visible Difference, Stronger Hair, Less Breakage, Smoother Hair, Defined Curl/Wave Pattern
    Rated 5 out of 5 stars
    6 hours ago
    Amazing

    The one item I will splurge on and purchase over and over. The only thing that has saved my bleached hair. Well worth the price

  • Kayla H.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Dryness
    Hair Type Straight/Wavy
    My Results Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    Yesterday
    love!!

    my hair has been bleached multiple times and instantly feels better as soon as this mask touches it :’) finally starting to be able to grow my hair out healthily !!

  • Jorge C.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 18 - 24
    Hair Concern Chemical damage, Split-Ends
    Hair Type Fine/Thin, Medium Density
    My Results Less Breakage, Stronger Hair, Smoother Hair, Soft Touchable Hair, Shinier Hair
    Rated 5 out of 5 stars
    4 days ago
    I love this hair mask!!

    Si far I’ve used it once.. because you’re supposed to apply and then leave it for 4 to 6 washes so it’s been a minute. I wanted to see how my hair reacted to it and so far it’s been great. My hair feels softer. I don’t see white tips meaning split ends it’s like a magic eraser honestly, of course it’s not gonna heal completely all really chemically damage hair in one go which is my case. . I did a nanoplasty, which is similar to keratin treatment… my hair was already very dry and brittle and chemically treated before I got in my hair every color of the rainbow for me to end up with dark brown hair, dyed red for years it just it was bad…because of how dry it was I got to the point where it was like super frizzy and I wanted it to be straight and shiny like a lot of the videos on TikTok so I got it done and that just fried my hair completely at least the tips… it was so bad that in the first picture that I attached my all of my hair on the tips started bending in weird ways. It didn’t matter if I dried it with a hairdryer air dried it anything it was bending weird like it was getting almost curly, but I didn’t have any pattern. It was bad like you would touch my hair and it was feeling soft and then the tips super coarse and dry.. it almost felt like if you were touching a broom like it was bad. at some point I kind of started cutting the tips because I was like there’s no fixing this. Tried everything in the book her mass treatments anything I didn’t know about K18.. my hair…

    K Profile picture for K18Hair
    K18Hair
    2 days ago

    Thank you so much for sharing your experience, Jorge! We're so happy to hear the Jumbo Leave-In Molecular Repair Hair Mask is already making such a difference after just one use. It sounds like your hair has been through a lot, and we completely understand how frustrating that journey must have been. We're thrilled that you're already noticing softer hair and fewer split ends - that's exactly what our mask is designed to do! We know it takes time to repair severe damage, but it sounds like you're on the right track. Thank you for giving K18 a try and for taking the time to share your detailed review with us ✨

  • Nataliya M.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 35 - 44
    Hair Concern Heat damage, Frizz, Color-care, Dryness, Fragile/brittle hair
    Hair Type Medium Density
    My Results Less Frizz, Stronger Hair, Smoother Hair, Less Breakage, Soft Touchable Hair
    Rated 5 out of 5 stars
    5 days ago
    The product is of excellent quality. I will buy again.

    The product is of excellent quality. I will buy again.

    K Profile picture for K18Hair
    K18Hair
    4 days ago

    Thank you so much, Nataliya! We're thrilled to hear you love the quality of the Jumbo Leave-In Molecular Repair Hair Mask and that you're planning to purchase again. Your support means the world to us! ✨

  • Jen W.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 25 - 34
    Hair Concern Fragile/brittle hair, Split-Ends, Dryness, Chemical damage, Frizz
    Hair Type Medium Density
    My Results Less Frizz, Visible Difference, Stronger Hair, Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    1 week ago
    Saving my blonde hair

    I really do believe this is making my bleached hair stronger. My hair at the top of my head feels stronger while the bottom from previous bleach damage is fragile. But as it’s growing out I feel like becoming healthier and stronger. I believe I can still be blonde and have long hair with this product.

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you so much, Jen! We're absolutely thrilled to hear the Jumbo Leave-In Molecular Repair Hair Mask is helping strengthen your bleached hair and giving you hope for maintaining healthy, long blonde hair! It's amazing that you're already noticing the difference in strength as your hair grows out. Your support and trust in our products means the world to us ✨

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