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full-size leave-in molecular repair hair mask

4-minute leave-in treatment to reverse hair damage
Rated 4.7 out of 5
Based on 7604 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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  • 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 508 reviews
Weightless oil that strengthens, repairs damage + reduces frizz

PEPTIDE PREP™ detox shampoo

Rated 4.8 out of 5
Based on 310 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 4.7 out of 5
Based on 7604 reviews
  • 5 Stars
    6231 Reviews
  • 4 Stars
    692 Reviews
  • 3 Stars
    308 Reviews
  • 2 Stars
    147 Reviews
  • 1 Star
    226 Reviews
92% of reviewers would recommend this product to a friend
7604 Reviews
Reviewed by Judit Rizo L.
Verified Buyer
I recommend this product
Age
45 - 54
Hair Concern
  • Color-care
  • Frizz
  • Split-Ends
Hair Type
  • Curly/Coily
My Results
  • Bouncy Hair
  • Stronger Hair
  • Defined Curl/Wave Pattern
  • Soft Touchable Hair
  • Shinier Hair
Rated 5 out of 5
Review posted

K18 Leave in

My hair looks so good that people asked me if is real :)))

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K18Hair

We appreciate your review!

Reviewed by barbara h.
Verified Buyer
I recommend this product
Age
55 - 64
Hair Concern
  • Chemical damage
  • Heat damage
  • Fragile/brittle hair
  • Split-Ends
  • Extending time between washes
Hair Type
  • Fine/Thin
My Results
  • Less Frizz
  • Less Breakage
  • Shinier Hair
  • Cleaner, fresher hair
  • Odor eliminated
Rated 5 out of 5
Review posted

Amazing !

I first order the smaller bottle ...huge fan here.

I'm not going all in and going for it.

Worth the money.

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K18Hair

We appreciate your review Barbara!

Reviewed by Carol D.
Verified Buyer
I recommend this product
Age
65+
Hair Concern
  • Chemical damage
  • Frizz
  • Dryness
  • Extending time between washes
  • Color-care
Hair Type
  • Medium Density
  • Curly/Coily
My Results
  • Bouncy Hair
  • Defined Curl/Wave Pattern
  • Soft Touchable Hair
  • Cleaner, fresher hair
Rated 5 out of 5
Review posted

Amazing product!

This keeps my hair fresh and clean of all other products and lets my natural curl come through! Thank you so much

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K18Hair

Thank you for your review Carol!

Reviewed by Jacqueline
I recommend this product
Rated 5 out of 5
Review posted

5 Stars

I love this product when used with the shampoo. It leaves my hair smooth and it feels in really good condition.

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K18Hair

We appreciate your 5 star review!

Reviewed by Joan W.
Verified Buyer
I recommend this product
Age
65+
Hair Concern
  • Color-care
  • Frizz
  • Chemical damage
Hair Type
  • Medium Density
  • Curly/Coily
My Results
  • Less Frizz
  • Bouncy Hair
  • Visible Difference
  • Defined Curl/Wave Pattern
  • Soft Touchable Hair
Rated 5 out of 5
Review posted

Wonderful product!!!

Fab product!! Did miracles for my hair!!

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K18Hair

Thank you Joan! We appreciate your review!

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