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Leave-in molecular repair hair mask 50mL
1. patented peptide reverses damage 2. highly concentrated formula 3. for all hair types 4. works in 4 minutes 5. easy leave-in, no rise needed 6. vegan & cruelty-free
Before and after using k18 professional leave in hair mask and professional hair mist.
Before and after using k18 professional leave in hair mask and professional hair mist.
Before and after using k18 professional leave in hair mask and professional hair mist.
Before and after using k18 professional leave in hair mask and professional hair mist.
full size leave-in molecular repair hair mask- 50 does per bottle.
Before and after image using detox, mask, conditioner, and oil
highly concentrated formula = a little goes a long way
Curly hair before using K18 mask and curly hair after using K18 mask.
full size leave in mask- start with 1 pump add more as needed. Mini size mask- start with 3 pumps add more as needed.
Clinically proven to reverse damage from: bleach + color, chemical services, and heat.
Where does K18 fit into your routine? 1. Shampoo (skip conditioner) 2. Towel dry 3. K18 4. wait for minutes 5. everything else
tile bestseller | color: black
4.9
Rated 4.9 out of 5 stars
1,929 Reviews

full-size leave-in molecular repair hair mask

Retail size of our 4-minute leave-in treatment to reverse hair damage

Professional Only

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Description

A retail-sized version of the K18 mask helps to maintain your client's hair strength and elasticity in-between salon appointments. This leave-in treatment mask for all hair types that reverses damage in 4 minutes. Patented peptide technology works to repair damage from bleach + color, chemical services, and heat* — restoring 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

Takes damage repair further – biomimetic peptide seamlessly fits in and reconnects 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 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 and with every service

  • 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, and heat*.

  • pH-optimized (5.0-6.0) to help minimize cuticle swelling + put hair proteins in their most resilient state after salon service or shampoo

  • Cream format enables easy, lightweight application across all hair types, with detangling and softening benefits.

  • Vegan, color-safe, cruelty-free

  • DO clarify before K18 if your client is 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
  • 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
molecular repair hair oil
4.9
Rated 4.9 out of 5 stars
417 Reviews
Weightless oil that strengthens, repairs damage + reduces frizz Log In / REGISTER
PEPTIDE PREP™ detox shampoo
4.9
Rated 4.9 out of 5 stars
253 Reviews
Retail size of our color-safe, non-stripping clarifying shampoo formulated with the K18PEPTIDE™ Log In / REGISTER

Description

A retail-sized version of the K18 mask helps to maintain your client's hair strength and elasticity in-between salon appointments. This leave-in treatment mask for all hair types that reverses damage in 4 minutes. Patented peptide technology works to repair damage from bleach + color, chemical services, and heat* — restoring strength, softness, smoothness, and bounce to hair.

20+ billion TikTok views 🔥 

*Disclaimers

got questions?
Get started here
K18 is engineered to work with every hair type, in every service, and with every routine.
Traditional conditioners leave a film on hair 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 styling product.
Water in damp hair swells the cuticle (the outside layer of hair) to open the gates for our biomimetic peptide to enter and travel to the innermost layers of hair. If the gates aren’t open, the product will stay on the surface—giving you mostly superficial repair. By applying on damp hair, you can use less, waste less, and still get the best results.
Think of the K18 mask as a highly concentrated treatment. It restores hair’s strength + elasticity in the innermost layers of hair, instead of traditional conditioners that coat the outside of hair. After the 4-minute wait time post-K18 mask, feel free to add a leave-in for a boost of conditioning if needed.
Yes, both formulas are the same. The PRO mask is conveniently sized for PRO use.

healthier hair with every use

Reverse damage in 4 minutes with our breakthrough K18 molecular repair technology.
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Shop K18 at professional wholesale pricing (no order minimums here).

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We have K18 experts on standby to answer allll your product and order questions.

how molecular repair compares
how K18 works

Traveling into the innermost layers of hair, our K18PEPTIDE™ renews strength along the width AND length of hair for lasting strength where it matters.

feel what's possible with K18
See how K18 unlocks our community's expression
4.9
Rated 4.9 out of 5 stars
Based on 1,929 reviews
1,929 reviews
  • Jamilla
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50 mL (WHOLESALE)
    I recommend this product
    Age 35 - 44
    Hair Concern Fragile/brittle hair, Dryness
    Hair Type Medium Density
    My Results Less Breakage, Soft Touchable Hair, Visible Difference
    Rated 5 out of 5 stars
    1 week ago
    My forever product

    I first purchased the trial package back in 2023, I loved it so I purchased the 50ml in September 2024. I just ran out of that bottle so I subscribed for a delivery every 6 months. This mask has strengthened my hair along with the other mask and conditioner I use after each wash. 2024 I also had a baby which caused my hair to thin, k18 established the bonds of my hair so that I would lose my length, my hair is still coming together after giving birth and I know this mask has done wonders for my hair. I had bad hair loss after all three of my pregnancy and this is the only product I repurchase because of the effects. Blue heart picture is 2024 and pink shirt is now 2025.

    K18Hair PRO
    5 days ago

    Thank you for your review and continued support, Jamilla!

  • Crystal C.
    Verified Buyer
    Reviewing
    Professional Molecular Repair Mask 150 mL (WHOLESALE)
    I recommend this product
    Age 35 - 44
    Client Hair Concerns Split Ends, Fragile/Brittle Hair, Chemical Damage, Heat Damage, Dryness
    Client Hair Types Fine/Thin, Medium Density, Curly/Coily, Straight/Wavy, Grey Hair
    Client Results Visible Difference, Less Breakage, Stronger hair, Smoother Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    1 week ago
    Miracle Product!!

    Having been licensed almost 20 years now, I was always telling my clients: when it comes to overprocessed or damaged hair, there is no miracle product that can fix it, it just needs cutting off. Not anymore!! This mask has saved sooo many inches from being chopped, and on my own hair too! I live in Hawaii and am

    In the sun and saltwater quite often and this has kept me from having to have short hair! It’s amazing. Nothing like it.

    K18Hair PRO
    1 week ago

    This is why we do what we do, it truly warms our heart to hear how K18 makes an impact on our community! Thank you for your stellar review, Crystal!

  • Liv W.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50 mL (WHOLESALE)
    I recommend this product
    Age 18 - 24
    Hair Concern Frizz, Fragile/brittle hair, Dryness
    Hair Type Fine/Thin
    My Results Stronger Hair, Less Breakage, Smoother Hair, Shinier Hair
    Rated 5 out of 5 stars
    3 weeks ago
    Repairing my Hair🪮👩‍🔧💁‍♀️

    I have not used this product for a long time, BUT after using it I can somewhat feel my hair. The pictures I have added are what my hair currently looks like/before I used K18. I have the other products sitting in my cart ready to buy because I feel as if K18 can take my hair to the next level.

    K18Hair PRO
    3 weeks ago

    Thank you for your 5-star review! If you need any product recommendations or suggestions on usage we would love to assist you.

  • Megan L.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50 mL (WHOLESALE)
    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
    1 month ago
    Love it

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

    K18Hair PRO
    1 month ago

    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 50 mL (WHOLESALE)
    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
    1 month 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!!

    K18Hair PRO
    1 month ago

    What an amazing stylist! Thank you for your review!

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