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best seller
4.7
Rated 4.7 out of 5 stars
8,009 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
  • 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

  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
  • 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
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Rated 4.8 out of 5 stars
710 Reviews
Weightless oil that strengthens, repairs damage + reduces frizz
PEPTIDE PREP™ detox shampoo
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Color-safe, non-stripping clarifying shampoo with the K18PEPTIDE™

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.
Straight bleached hair after using K18 mask.
Straight bleached hair before using K18 mask.

healthier hair with every use

Reverse damage in 4 minutes with our breakthrough K18 molecular repair technology.
the K18 difference
Feel what’s possible with fewer steps, less waste + less time.
efficacy
patented K18PEPTIDE™ powers deeper + lasting repair.
simplicity
fewer steps for a streamlined routine.
speed
results in one 4-minute use.
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
4.7
Rated 4.7 out of 5 stars
Based on 8,009 reviews
8,009 reviews
  • Kim P.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 55 - 64
    Hair Concern Chemical damage, Color-care, Heat damage, Split-Ends, Fragile/brittle hair
    Hair Type Fine/Thin
    My Results Less Frizz, Less Breakage, Bouncy Hair, Visible Difference, Smoother Hair
    Rated 5 out of 5 stars
    Yesterday
    An absolute must have

    Miracle worker. Love this stuff. Works great

  • amanda s.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 18 - 24
    Hair Concern Dryness, Split-Ends, Frizz
    Hair Type Fine/Thin, Curly/Coily
    My Results Less Frizz, Stronger Hair, Less Breakage, Soft Touchable Hair
    Rated 4 out of 5 stars
    1 week ago
    The smell

    I love the smell so much! I’m glad that I bought this and waiting to see how this makes my hair look

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you Amanda!

  • Linda C.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 65+
    Hair Concern Fragile/brittle hair, Dryness, Split-Ends, Frizz
    Hair Type Medium Density
    My Results Bouncy Hair, Visible Difference, Stronger Hair, Less Breakage, Smoother Hair
    Rated 5 out of 5 stars
    1 week ago
    A GIANT SIZED LEAVE IN CONDITIONER IS THE BEST EVER!!

    so happy with my giant sized Leave-in conditioner!

    By the way, this product is Awesome!!

    Happy Grama customer here

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    We appreciate your review Linda! Thank you!

  • Gergana G.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Split-Ends, Oily hair/scalp
    Hair Type Fine/Thin
    My Results Visible Difference, Stronger Hair, Less Breakage, Soft Touchable Hair, Shinier Hair
    Rated 5 out of 5 stars
    2 weeks ago
    Love it!

    I absolutely love the mask! It’s definitely worth the hype—it has completely transformed my hair, making it so much healthier, even after years of bleaching.

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Beautiful hair! Thank you for your review!

  • Carissa L.
    Verified Buyer
    Reviewing
    Mini Leave-In Molecular Repair Hair Mask 15 mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Dryness, Split-Ends, Fragile/brittle hair
    Hair Type Medium Density
    My Results Visible Difference, Less Breakage, Stronger Hair
    Rated 5 out of 5 stars
    2 weeks ago
    Helped my hair in +4 washes, drastic difference

    Bought K18 to help my severely damaged hair from bleach. There is a huge visible difference between when I first started using it to after 4 washes. Amazing stuff.

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you for your 5-star review! We appreciate it!

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