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Rated 4.7 out of 5
Based on 7797 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 4.7 out of 5
Based on 599 reviews
Weightless oil that strengthens, repairs damage + reduces frizz
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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

reviews

average rating 4.7 out of 5
Based on 7797 reviews
  • 5 Stars
    6411 Reviews
  • 4 Stars
    699 Reviews
  • 3 Stars
    310 Reviews
  • 2 Stars
    148 Reviews
  • 1 Star
    229 Reviews
92% of reviewers would recommend this product to a friend
7797 Reviews
Reviewed by kodi k.
Verified Buyer
I recommend this product
Age
25 - 34
Hair Concern
  • Fragile/brittle hair
  • Split-Ends
  • Dryness
Hair Type
  • Medium Density
  • Straight/Wavy
My Results
  • Visible Difference
  • Soft Touchable Hair
  • Cleaner, fresher hair
  • Shinier Hair
  • Smoother Hair
Rated 5 out of 5
Review posted

Excellent

Immediately after the 1st use I could feel a difference, after the 4th wash I could see it! Will be purchasing again. A new staple in my routine

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Reviewed by Sandy S.
Verified Buyer
I recommend this product
Age
45 - 54
Hair Concern
  • Color-care
  • Heat damage
  • Dryness
  • Frizz
Hair Type
  • Medium Density
My Results
  • Less Frizz
  • Smoother Hair
  • Less Breakage
  • Stronger Hair
  • Soft Touchable Hair
Rated 5 out of 5
Review posted

I Love this stuff

I shampoo my hair and put in one squirt before blow drying. I do not have to use any product in my hair and it comes out so smooth. I love it!

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K18Hair

Look at that color 😍! Thank you Sandy!

Reviewed by Vivian P.
Verified Buyer
Leave-In Molecular Repair Hair Mask Sample
Reviewing
Leave-In Molecular Repair Hair Mask Sample
I recommend this product
Rated 5 out of 5
Review posted

Wha a different difference!!!!

Started using K-18 2 years ago and the difference is incredible!!

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K18Hair

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

Reviewed by TANYA G.
Verified Buyer
I recommend this product
Age
25 - 34
Hair Concern
  • Chemical damage
  • Frizz
  • Fragile/brittle hair
  • Dryness
  • Split-Ends
Hair Type
  • Medium Density
  • Straight/Wavy
My Results
  • Visible Difference
  • Stronger Hair
  • Smoother Hair
  • Soft Touchable Hair
  • Less Breakage
Rated 5 out of 5
Review posted

saved my hair

I have finally grown my hair to hip length, but years of dyeing made the lower lengths & ends feel SUPER dry & damaged. After trimming ~1in. to get rid of split ends, I used K18 (after 6 consecutive washes, then once a week) & have gotten to a point where I feel confident I won't have to cut off more hair for it to keep feeling soft & healthy. This is one product I've had several empties of bc it really does work for me, especially since I want to continue dyeing my hair as it grows. If they had ever made the 5oz available for the public, I would be buying that without hesitation.

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K18Hair

We will pass your request to our product development team. Thank you for your review!

Reviewed by Gayle A.
Verified Buyer
I recommend this product
Age
55 - 64
Hair Concern
  • Heat damage
  • Extending time between washes
Hair Type
  • Grey Hair
My Results
  • Stronger Hair
  • Cleaner, fresher hair
  • Shinier Hair
  • Smoother Hair
Rated 5 out of 5
Review posted

Amazing Product

I love the way my hair feels after I use this product. Best out there.

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K18Hair

We appreciate your 5-star review! Thank you Gayle!

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