Name: Leave-In Molecular Repair Hair Mask 50mL
Brand: K18Hair
SKU: K18-31005
Price: 75.00 USD
Availability: InStock

leave-in molecular repair hair mask

4-minute leave-in treatment to reverse hair damage

Rated 4.5 out of 5

Based on 593 reviews

An at-home leave-in treatment infused with our patented K18Peptide™ that works to repair even the most extreme damage, renewing hair to its most youthful, healthy state.

Repairs Damage Caused By

Bleach + Color
Heat
Chemical Services

Full Size - $75.00 50 mL Try-it Size - $12.00 5 mL

FREE SHIPPING. FREE RETURNS.

more to know

creates hair like new
Traveling deeper into the inner layers of hair than traditional repair products, our revolutionary patented K18Peptide™ is just the right size and makeup to fit in and reconnect broken keratin chains, renewing hair with strength, softness, smoothness, and bounce. You can feel and see the difference with the first use.

See dosage chart for exact usage. For best results, use for the first 4-6 consecutive washes, then every 3-4 washes as needed to maintain hair strength.

how to use

IN the shower

Shampoo, do not condition.

OUT of the shower

Towel dry thoroughly.
Begin with 1 pump of the K18 Mask and add more as needed depending on the length, thickness, and condition.
Work evenly into hair from ends to roots, one pump at a time.
Let sit for 4 minutes to activate.
Do NOT rinse out.
Style as usual.

Dosage Guide:

do's + don'ts

DO use a clarifying shampoo if you’re a heavy product or dry shampoo user to remove buildup and help our peptide penetrate and get where it needs to go.
DO wait the full 4 minutes before styling or applying other product
DO use every 4-6 shampoos consecutively to see and feel ongoing results

DON’T condition your hair before application (trust us, most won’t need it after K18, if you still need, add a leave-in after the 4-minute window is up post-application)
DON’T overuse, a little goes a long way.
DON’T rinse out. This is a leave-in, so you know, leave it in!

key benefits

Our K18Peptide™ is clinically proven to reverse damage in just 4 minutes.

Heals damage from bleach, color, chemical services, and heat
Restores strength, softness, smoothness, and bounce
Doesn’t wash away with shampoo, leaving lasting results
Vegan, color-safe, cruelty-free

91% original strength*
94% original elasticity*

* Results observed in a clinical study while using mist and mask as part of a bleaching treatment. Results may vary depending on hair type, quality and history.

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.

what you can expect
by damage type

backed by science,
loved by stylists

Our community of stylists and colorists believe K18 is liberating hair—no matter the hair type or generation.

“K18 allows me to go everywhere I want to go with my color work and the end result is my guests get to be bright and shiny and healthy.”

– Christine Thompson, Director of Color at Spoke & Weal

have questions?

we have answers.

How does K18 work?

When hair gets damaged, the polypeptide chains (keratin chains) that make up the inner structure of hair strands become weakened and break. For context, there are billions and billions of polypeptide chains (keratin chains) in a single strand of hair. When these are damaged, hair’s core structure responsible for elasticity and strength becomes compromised and as a result it loses its resiliency and shine—or the look and feel of healthy hair.

After spending a decade in the lab scanning and testing all amino acid sequences across the entire keratin genome that makes up human hair searching for a breakthrough, we discovered one unique sequence (a bioactive peptide) that brings damaged hair back to its original, youthful state. This is our K18Peptide™.

Traveling deeper into the inner layers of hair than traditional repair products, our revolutionary peptide is just the right size and makeup to fit in and reconnect those broken polypeptide chains (keratin chains). And because our peptide is a bit of an overachiever, as a result of this reconnection, any disturbed disulfide bonds are also re-conformed.

Our peptideemploys biomimetics to get the job done. To put it simply: Biomimetics is the practice of learning from and mimicking nature. Mimicking the natural structure of keratin building blocks (amino acid sequences), our K18 bioactive peptide is recognized as natural by the hair. It’s not washed away by water or shampoo like traditional bonding agents either, making K18 a genuine, lasting solution for damaged strands.

What is the K18Peptide™?

Our patented peptide is a unique sequence of amino acids that travels deep into hair’s core structure to fit in and reconnect broken polypeptide chains (keratin chains) responsible for hair strength and elasticity.

An Analogy: When building proteins, the order of the amino acids determines the kind of protein and its properties, much like the way letters are arranged to make meaningful words and sentences. In the same way the order and where each word sits in a sentence leads to its overall meaning, K18 is the magic word that fits right in, integrating itself with the keratin chains as the hair recognizes it as a natural building block.

Why should I skip conditioner?

K18 is most effective on clean, towel-dried hair. Conditioners use silicones and conditioning agents that form heavy coatings on hair, preventing our peptide from reaching the broken polypeptide chains deep inside hair’s inner layer.

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. Our unique blend of 3 alcohols function to open up the hair cuticle so the K18Peptide ™ can penetrate the inner most layer of hair, reaching the broken polypeptide chains (keratinchains). Here the alcohol serves as an agent to optimize the hair environment for K18 to work on a deeper level.

When should I expect to see results?

You will start to see stronger, softer, healthier hair after just one use.

renews strength, softness, smoothness, and bounce

Curly

Coily

Straight

K18 strengthens hair’s core structure, restoring damaged curl patterns and leaving strands looking and feeling like new.

K18 reconnects broken keratin chains, restoring hairs elasticity and strength meaning coily hair can be renewed and brought back to its original springy, healthy shape.

K18 restores strength, softness, smoothness, and bounce so even the sleekest hair can feel like new.

Reviewed by Patricia R.

Verified Buyer

Reviewing

Leave-In Molecular Repair Hair Mask 50mL

I recommend this product

Age

35 - 44

Hair Concern

Chemical damage
Heat damage
Color-care
Fragile/brittle hair
Dryness

Hair Type

Fine/Thin
Straight/Wavy

My Results

Visible Difference
Smoother Hair
Soft Touchable Hair
Less Breakage

Rated 5 out of 5

Review posted

K18

I recommend this product 100%

It has made my bleach damage hair super soft on the first try!

Was this helpful?

Reviewed by JP H.

Verified Buyer

Reviewing

Leave-In Molecular Repair Hair Mask 50mL

I recommend this product

Age

65+

Hair Concern

Color-care
Fragile/brittle hair
Split-Ends
Chemical damage

Hair Type

Fine/Thin

My Results

Bouncy Hair
Visible Difference
Stronger Hair
Less Breakage
Smoother Hair

Rated 5 out of 5

Review posted

This is the gold standard for repairing hair

I am 67 and therefore have used every hair product that has come down the pike. I color my hair and it is fine, so I'm always looking for products that strengthen my hair and don't strip it of the color. I'm pretty blond at the moment and certain conditioners can make me brassy. Not this one! I feel this is a totally new and different product than I have ever used. It absorbs into my hair, doesn't weigh it down and make it look greasy, in fact you really can't tell I have a product in except for the fact that my hair looks and feels fabulous. It feels and looks better than it ever has in my life and all with a little dab of K18! It takes 10 seconds to apply, no waiting, feeling goopy or sitting there with a towel hoping something works. This does the job immediately and the results are almost unbelievable with one application. Each time I use it my hair just gets better and better. I love it and will keep using it.

Was this helpful?

Reviewed by Korinne J.

Verified Buyer

Reviewing

Leave-In Molecular Repair Hair Mask 50mL

I recommend this product

Age

25 - 34

Hair Concern

Chemical damage
Heat damage
Fragile/brittle hair
Split-Ends

Hair Type

Medium Density

My Results

Bouncy Hair
Visible Difference
Stronger Hair
Less Breakage
Shinier Hair

Rated 5 out of 5

Review posted

Helping so many years of damage

Love being a blonde but the damage can add up quick. This product makes the hair repair and ready for the touch ups. Love it 😍

Was this helpful?

Reviewed by Melissa H.

Verified Buyer

Reviewing

Leave-In Molecular Repair Hair Mask 5mL

I recommend this product

Age

35 - 44

Hair Concern

Chemical damage
Heat damage
Fragile/brittle hair
Dryness

Hair Type

Medium Density

My Results

Visible Difference
Soft Touchable Hair
Less Frizz

Rated 5 out of 5

Review posted

Awesome!!

I have very damaged, over processed hair and this is life changing! I ordered the sample first because I never believe anything will actually work. After 1 use I was sold and ordered the full size!

Was this helpful?

Reviewed by Kim M.

Verified Buyer

Reviewing

Leave-In Molecular Repair Hair Mask 50mL

I recommend this product

Age

65+

Hair Concern

Chemical damage
Fragile/brittle hair
Dryness

Hair Type

Fine/Thin
Straight/Wavy
Grey Hair

My Results

Visible Difference
Soft Touchable Hair
Shinier Hair
Stronger Hair
Less Breakage

Rated 5 out of 5

Review posted

Miracle for my hair!

I have been very happy with this product. My hair needed help! Now I’m not afraid of ruining my hair. Great repair!

Was this helpful?