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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 7443 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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more to know

  • 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

key benefits

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

how to use

  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

dos and don'ts

  • 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

ingredients

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 420 reviews
Weightless oil that strengthens, repairs damage + reduces frizz View Molecular Repair Hair Oil product

PEPTIDE PREP™ detox shampoo

Rated 4.8 out of 5
Based on 259 reviews
Color-safe, non-stripping clarifying shampoo with the K18PEPTIDE™ View PEPTIDE PREP™ detox shampoo 8.5oz product

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.

how does the k18 mask work?

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.

what is the k18peptide™?

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

why skip conditioner?

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.

i noticed there’s alcohol in the formula, isn’t that bad for you?

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).

when should i expect to see results?

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.
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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 7443 reviews
  • 5 Stars
    6090 Reviews
  • 4 Stars
    680 Reviews
  • 3 Stars
    305 Reviews
  • 2 Stars
    146 Reviews
  • 1 Star
    222 Reviews
92% of reviewers would recommend this product to a friend
Customer photos and videos
7443 Reviews
Reviewed by MJR
I recommend this product
Age
35 - 44
Hair Concern
  • Chemical damage
  • Heat damage
  • Color-care
  • Frizz
  • Fragile/brittle hair
Hair Type
  • Medium Density
My Results
  • Stronger Hair
  • Visible Difference
  • Smoother Hair
  • Less Breakage
  • Shinier Hair
Rated 5 out of 5
Review posted

This is IT for me!

For several years I have struggled with extreme breakage in the hair framing my face. Years of bleaching, stress and hormones (I’m 43) my bangs were 2in in length down to my temples. I would look at old pics of my hair and want to cry. I tried everything and have spent a small fortune but K18 saved my hair! I started with the pack of minis and that’s all it took to show me a drastic change begin with my hair. It is super healthy and growing now. I am forever grateful for this product! I use this along with the peptide prep shampoo and the regular K18 shampoo and conditioner. Hair rescuer!

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K18Hair

Thank you MJR for your review!

Reviewed by Lori
I don't recommend this product
Rated 1 out of 5
Review posted

1 Star

Subscription not my intention. Have contacted K18 with no response

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K18Hair

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Reviewed by Anne M.
Verified Buyer
I recommend this product
Age
45 - 54
Hair Concern
  • Chemical damage
  • Heat damage
  • Frizz
  • Fragile/brittle hair
  • Dryness
Hair Type
  • Fine/Thin
  • Straight/Wavy
My Results
  • Less Frizz
  • Bouncy Hair
  • Visible Difference
  • Stronger Hair
  • Less Breakage
Rated 5 out of 5
Review posted

Review

This is the best product I could’ve ever got.

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K18Hair

Thank you for your review!

Reviewed by Paola F.
Verified Buyer
I recommend this product
Age
18 - 24
Hair Concern
  • Chemical damage
  • Fragile/brittle hair
  • Dryness
  • Split-Ends
Hair Type
  • Medium Density
  • Straight/Wavy
  • Fine/Thin
My Results
  • Less Frizz
  • Visible Difference
  • Soft Touchable Hair
  • Shinier Hair
  • Stronger Hair
Rated 5 out of 5
Review posted

Reverses color and bleach damage!!

Forget all the oils or leave in conditioners. After dyeing my hair with BLACK drug store box dye, then BLEACHING it (big no no) and dyeing it bright pink, it felt like straw when I’d try and wash it in the shower. 2 rounds of 8 washes with this and it was back to normal! Nothing has ever worked like this, not even Olaplex. If you’ve got years of box dye or bleaching on your hair, this will solve it!!

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K18Hair

Thank you Paola! We appreciate your review!

Reviewed by Tina R.
I recommend this product
Age
25 - 34
Hair Concern
  • Chemical damage
  • Heat damage
  • Frizz
  • Fragile/brittle hair
  • Oily hair/scalp
Hair Type
  • Medium Density
  • Straight/Wavy
My Results
  • Less Frizz
  • Visible Difference
  • Less Breakage
  • Soft Touchable Hair
Rated 5 out of 5
Review posted

Amazingggg

I did the mini to test it, and let me tell you I’m ordering the bigger size now I did the mini because it’s so expensive and I didn’t want to pay tons of money for it not to work but this stuff does the job for sure I’m a blond girl and I love my blond but my hair has gotten weak now I see the difference. This day 4 of using this product. I did my bleach touch up Friday and it was gummy from the ends and breaking so I cut what I could with out losing all my hair started to use K18 and this is where we are !!!! It’s a must

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K18Hair

Thank you Tina for your review! Our molecular repair is a progressive treatment! You will notice your hair will get better with each use.

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