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full-size leave-in molecular repair hair mask

4-minute leave-in treatment to reverse hair damage
Rated 4.6 out of 5
Based on 7508 reviews

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
OR
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=
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  • 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

K18 molecular repair hair oil

Rated 4.7 out of 5
Based on 465 reviews
Weightless oil that strengthens, repairs damage + reduces frizz

PEPTIDE PREP™ detox shampoo

Rated 4.8 out of 5
Based on 288 reviews
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

reviews

average rating 4.6 out of 5
Based on 7508 reviews
  • 5 Stars
    6146 Reviews
  • 4 Stars
    684 Reviews
  • 3 Stars
    307 Reviews
  • 2 Stars
    147 Reviews
  • 1 Star
    224 Reviews
92% of reviewers would recommend this product to a friend
Customer photos and videos
7508 Reviews
Reviewed by Lisa
I recommend this product
Rated 5 out of 5
Review posted

5 Stars

Good product

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K18Hair

Thank you for your 5 star review!

Reviewed by Kelley S.
Verified Buyer
I recommend this product
Age
35 - 44
Hair Concern
  • Chemical damage
  • Heat damage
  • Frizz
Hair Type
  • Curly/Coily
My Results
  • Bouncy Hair
  • Visible Difference
  • Less Frizz
  • Defined Curl/Wave Pattern
  • Soft Touchable Hair
Rated 5 out of 5
Review posted

5,000 stars

I have never recommended a product to so many friends in such a short period of time. I didn't even think my hair needed repairing until I tried K18 Molecular Hair Repair Mask. I noticed a change in my hair within 3 days of use, it was bouncier, smoother, less fuzzy and tangly. I am so excited about it!

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K18Hair

We love this for you! Thank you for your review Kelley!

Reviewed by Monoah V.
Verified Buyer
Reviewing
Leave-In Molecular Repair Hair Mask 15 mL (WHOLESALE)
I recommend this product
Age
35 - 44
Rated 5 out of 5
Review posted

LOVE

Absolutely adore this product

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K18Hair

We appreciate your review!

Reviewed by Maria
Verified Reviewer
I recommend this product
Age
25 - 34
Hair Concern
  • Heat damage
Rated 5 out of 5
Review posted

one question

How much time should there be between uses?

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K18Hair

You will use with your usual wash routine.

Reviewed by Carol B.
Verified Buyer
I recommend this product
Age
55 - 64
Hair Concern
  • Frizz
  • Dryness
Hair Type
  • Medium Density
  • Grey Hair
  • Curly/Coily
My Results
  • Less Frizz
  • Defined Curl/Wave Pattern
  • Smoother Hair
  • Soft Touchable Hair
  • Visible Difference
Rated 5 out of 5
Review posted

Been using for years!

My hair looks and feels it’s best when I use this regularly. My stylist introduced me years ago. Still in love.

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K18Hair

Thank you Carol! We appreciate your review!

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