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4.7
Rated 4.7 out of 5 stars
8,032 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.

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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 8,032 reviews
8,032 reviews
  • Krystal P.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    Age 35 - 44
    Hair Concern Chemical damage, Heat damage, Frizz, Fragile/brittle hair, Split-Ends
    Hair Type Straight/Wavy, Fine/Thin
    My Results Less Frizz, Visible Difference, Smoother Hair
    Rated 3 out of 5 stars
    4 days ago
    Does it do what it claims? Meh…

    So I have used this product for 6 washes, exactly as directed. My hair had been damaged by bleach. The improvement I saw was temporary. The first two uses, it really helped smooth my ends. However, that was temporary and I now am back to square one. I wish it had lived up to the hype. Great leave in, but it’s not correcting any damage and it’s not as effective as it was at first.

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    Depending on how damaged your hair is you may need to repeat the 6 consecutive washes. If you would love a personalized recommendation we can better assist you via email at Hello@K18Hair.com.

  • Briana Q.
    Verified Buyer
    Reviewing
    Full-Size Leave-In Molecular Repair Hair Mask 50mL
    I recommend this product
    Age 25 - 34
    Hair Concern Chemical damage, Fragile/brittle hair, Heat damage
    Hair Type Fine/Thin
    My Results Visible Difference, Stronger Hair, Less Breakage, Smoother Hair, Soft Touchable Hair
    Rated 5 out of 5 stars
    4 days ago
    Beyond Amazing

    I have had such damaged hair due to bleaching my hair for years and the stylist not making hair health a priority first, and I have since let my hair grow out its natural color however due to the damage my ends have not been healthy in years and continue to break. I have tried EVERYTHING for the last two years and have been disappointed over and over again UNTIL this product, I cannot even begin to describe the growth and health this product has been able to give me in just 1 1/2 months already. This product used with the other products of this brand has truly gave me my confidence back and I cannot wait to try more products from this brand. I am finally seeing amazing results. 10/10 recommend

    K Profile picture for K18Hair
    K18Hair
    Yesterday

    We love this for you! Healthy grow out! Thank you Briana!

  • Amanda M.
    Verified Buyer
    Reviewing
    Leave-In Molecular Repair Hair Mask Sample
    I recommend this product
    Rated 5 out of 5 stars
    5 days ago
    Love this product and what it has done for my hair

    I’ve purchased all three sizes of this product now. It has made my wiry grays more manageable. Same for my ends that were once bleached. My new growth is very soft.

    K Profile picture for K18Hair
    K18Hair
    5 days ago

    Thank you Amanda! Happy to hear you are enjoying your results!

  • Cherrie C.
    Verified Buyer
    Reviewing
    Jumbo Leave-In Molecular Repair Hair Mask 100mL
    I recommend this product
    Age 65+
    Hair Concern Chemical damage, Dryness
    Hair Type Thick/Coarse
    My Results Defined Curl/Wave Pattern, Visible Difference, Less Frizz
    Rated 5 out of 5 stars
    1 week ago
    Jumbo repair Hair Mask

    Great Product. Leaves hair in excellent condition after chemical process

    K Profile picture for K18Hair
    K18Hair
    5 days ago

    Thank you Cherrie! K18 Molecular repair mask is amazing post chemical process!

  • 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
    1 week ago
    An absolute must have

    Miracle worker. Love this stuff. Works great

    K Profile picture for K18Hair
    K18Hair
    1 week ago

    Thank you Kim! We also agree that this is a miracle product!

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