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Leave-in molecular repair hair mask 15mL
get stronger, more resilient hair. left - 8x bleach without K18, right 8x bleach with K18
get stronger, more resilient hair. left - 8x bleach without K18, right 8x bleach with K18
where K18 molecular repair works
the K18 routine
maximze your repair
less is more
works for all hair types
where does K18 fit into your routine?
K18 routine guide
Rated 4.7 out of 5
Based on 7791 reviews

mini 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 3-9 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 595 reviews
Weightless oil that strengthens, repairs damage + reduces frizz
PEPTIDE PREP™ detox shampoo
Rated 4.8 out of 5
Based on 358 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 7791 reviews
  • 5 Stars
    6406 Reviews
  • 4 Stars
    698 Reviews
  • 3 Stars
    310 Reviews
  • 2 Stars
    148 Reviews
  • 1 Star
    229 Reviews
92% of reviewers would recommend this product to a friend
7791 Reviews
Reviewed by Adriana P.
Verified Buyer
I recommend this product
Age
35 - 44
Hair Concern
  • Heat damage
Hair Type
  • Curly/Coily
My Results
  • Stronger Hair
  • Visible Difference
Rated 5 out of 5
Review posted

Amazing

I just completed my 4th wash and applied the leave in mask after. I slowly noticed after each time my curls coming back to life after heat damage from a straightener. Thank you!

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K18Hair

K18 loves to bring the bounce back to those curls. Thank you for your 5-star review!

Reviewed by Maddelyne R.
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

Love this

Try this sample and I think I’m in love with the brand just one use following every step and it safe my hair I can’t wait to keep using it for 4 or 6 consecutive washes to se better results!!!

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K18Hair

We appreciate your review! Thank you Maddelyne!

Reviewed by car
Verified Buyer
I recommend this product
Age
35 - 44
Hair Concern
  • Chemical damage
  • Color-care
  • Split-Ends
Hair Type
  • Thick/Coarse
  • Curly/Coily
My Results
  • Visible Difference
  • Stronger Hair
  • Less Breakage
  • Soft Touchable Hair
  • Defined Curl/Wave Pattern
Rated 5 out of 5
Review posted

LOVE IT!!

I went blonde in june. this was my first time fully bleaching and toning all of my hair. I went from a level 2 to a level 9. I knew it was going to damage my hair - but I wasn't prepared for how bad. my friend is a hairstylist and she recommended k18 over that "other" brand. I’m eternally grateful she did because my hair is as healthy as it was before I bleached it. I love it so much, I will continue to use it even when I get bored of being blonde and grow it out because it makes my curls look amazing too!

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K18Hair

What a great friend to look out for your hair! Thank you Car! We appreciate your review!

Reviewed by Ellah
Verified Buyer
I recommend this product
Age
25 - 34
Hair Concern
  • Heat damage
  • Chemical damage
  • Frizz
Hair Type
  • Thick/Coarse
  • Curly/Coily
My Results
  • Defined Curl/Wave Pattern
  • Soft Touchable Hair
  • Visible Difference
  • Less Frizz
  • Bouncy Hair
Rated 5 out of 5
Review posted

Great treatment

Absolutely love this. It makes a huge difference in my thick, curly hair. Heat damaged areas are curly again , frizz is reduced and hair feels soft and strong.

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K18Hair

Our Molecular Repair mask works wonders on curly hair! Thank you for your review!

Reviewed by Debra N.
Verified Buyer
I recommend this product
Age
55 - 64
Hair Concern
  • Heat damage
  • Fragile/brittle hair
  • Dryness
  • Frizz
  • Split-Ends
Hair Type
  • Fine/Thin
My Results
  • Less Frizz
  • Visible Difference
  • Soft Touchable Hair
  • Smoother Hair
  • Less Breakage
Rated 5 out of 5
Review posted

Finally, the holy grail

I finally found something to help my parched, damaged looking hair. I work outside all day , every day, and my blonde hair always feels and looks dry. I’ve tried every deep conditioner out there. I’ve only used this three times and my hair looks and feels so much better. I was starting to think it was a lost cause. I love this product!

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K18Hair

Happy healthy hair journey! We appreciate your review!

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