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K18 Leave-In Molecular Repair Hair Mask

 
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Highlights

  • Increases shine
  • Ideal for bleached, dry hair
  • Detangles and softens

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Product Overview

K18 Leave-In Molecular Repair Hair Mask is a patented peptide hair mask to reverse damage from hair treatments.

In just four minutes, this professional, salon-grade hair treatment from K18 Biomimetic Hairscience heals damage from bleach, color treatments, styling heat and chemical services. Formulated with a first of it's kind, patented oligopeptide, also known as K18Peptide™, this bioactive treatment reduces split ends, breakage and color fade, while restoring elasticity, bounce, softness and strength. Unlike conditioning treatments that hydrate the outer layer of hair and bonding treatments that wash out over time, this K18 hair product actually heals hair from the inside out and produces results that won't wash away.

Key Features:

  • K18Peptide™, a unique patented peptide molecule, repairs broken keratin chains that make up the building blocks of hair
  • Heals damage from bleach, color, chemical services, heat, and mechanical styling
  • pH balance of 5.0-6.0
  • Doesn't wash away with shampoo, leaving lasting results
  • Vegan, color-safe and cruelty-free
  • Ideal for all hair types

Restore bounce, elasticity and hydration to damaged hair with K18 Leave-In Molecular Repair Hair Mask.

Highlights

  • Heals hair damage with K18Peptide™
  • Ideal after bleaching and chemical services
  • Unique, no-rinse treatment

Ingredients

Directions

Shipping & Returns

Free U.S. Shipping. Period. View Our Shipping Policy

Return Policy: This product is non-returnable

Return Policy: View Our Return Policy

Special Shipping Requirements: ORM-D Class
ORM-D classified products such as aerosol sprays, nail polish, perfume and products with high alcohol content may only be shipped using a ground method within the Continental US.

Availability: This product is no longer available.

Product Specifications

About the Brand

Customer Reviews (488)

Overall Rating

4.4
Based on 488 reviews

Review Summary

Read all reviews

488 Reviews

Profile picture of Reg6792.

Reg6792

from Maine

Age Group: 50-59

Curly, Dry Hair

Normal Skin

Verified Purchase

September 05, 2025

Not instant but def worth it!

Tried this as a last resort. I have fine, but coarse curly hair. After an illness I had massive hair loss and what remained was dry, frizzy and unmanageable. I tried every product available then I bought this. It was not and instant fix as some say, but I followed the directions used about 5 shampoos in a row and then spread to once every week to every two weeks. I definitely noticed a difference after about a month. My strands felt more dense, fuller without the curl being weighed down, less frizz and more manageable.

2 people found this helpful

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Vita

Straight, Color treated hair

Verified Purchase

August 24, 2025

Smooth and glossy hair

The results just get better the more you use it.

0 people found this helpful

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LovelySkin Customer

Verified Purchase

August 02, 2025

Great to get the shine and smoothness back!

Transformed my hair from straw brittle ends to very smooth ends. Works well and lasts a long time

0 people found this helpful

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LovelySkin Customer

from Colorado

Straight hair, Damage & split ends

Verified Purchase

July 23, 2025

Noticeable difference

This truly has made a difference in my hair. I have baby fine hair and this has added so much resilience after being fried by bleach. It’s expensive, but worth it!

1 person found this helpful

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AWL

Verified Purchase

June 08, 2025

Loved it but a lot of $$$

This strengthens your hair strands, but it is not cheap!

0 people found this helpful

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LovelySkin Customer

Verified Purchase

May 30, 2025

Repeat purchase

I always have this and will continue to buy it. It helps with damaged hair and I feel a significant difference after one use.

1 person found this helpful

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LovelySkin Customer

Verified Purchase

April 26, 2025

I really like this!

I really like this product. I have added in some new hair products over the last couple of years (including Olaplex and a Redken serum) and plan to keep using this. It is easy to use and incorporate into my hair routine.

0 people found this helpful

Profile picture of SaraR.

SaraR

Verified Purchase

February 13, 2025

For the impatient..your new bff

This is a perfect way to dramatically improve your hair without having to sit through a traditional hair mask that you have to leave in for 15-20 min and rinse out. All it takes is a few sprays ( for my shoulder length hair) after you get out of the shower and wait 4 min while you do other things .. and you are all set! I spray one spritz at a time into my palms (2 total) and work it into sections of my hair for even distribution. It takes less product than you think so a bottle lasts awhile. It even shortens your shower times since you don’t use a conditioner prior. I’m 48, and my highlighted hair is starting to look as healthy as it did in my 30’s. My husband told me yesterday that my hair looked “bouncy”.. and I didn’t even know that word was in his vocabulary. Buy this- it works .

1 person found this helpful

Profile picture of EmilyW007.

EmilyW007

Verified Purchase

December 03, 2024

I’m a believer

I was so skeptical of this stuff but I finally tried it and… I’m sold. It has helped repair lots of damage from coloring over the years. After learning about how it actually works, it makes sense! Super easy to use as well.

1 person found this helpful

Profile picture of Teacherkh.

Teacherkh

Verified Purchase

July 20, 2024

Good results

So far this is my favorite special treatment. I feel like it improves my hair annd I like that you don’t need to rinse it. Time saver.

1 person found this helpful

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LovelySkin Customer

Verified Purchase

July 19, 2024

Love

I love this! It has helped my hair to not break and because of that my hair has been able to grow out quickly. Have repurchased several times and will continue to do so.

0 people found this helpful

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LovelySkin Customer

Verified Purchase

July 15, 2024

Amazing

My hairdresser recommended this mask and I am very pleased. Amazing product will definitely buy it again. Game changer.

0 people found this helpful

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LovelySkin Customer

Verified Purchase

July 12, 2024

NEEDED

I get my hair bleached and this is a must.

0 people found this helpful

Profile picture of Beth1313.

Beth1313

Verified Purchase

June 26, 2024

Best thing I’ve ever purchased for my hair

I will never not use this product. I use it after every wash and my hair has never been healthier. Holy grail product for me.

0 people found this helpful

Profile picture of HarmonyZ.

HarmonyZ

Verified Purchase

March 04, 2024

Doesn’t make thin hair greasy

I used this product according to the label and it’s working great. I have fine/thin hair and it’s not weighed down at all. I use 1 to 2 pumps each time I use it. I can see less breakage where I wear my hair tie.

0 people found this helpful

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LovelySkin Customer

Verified Purchase

February 27, 2024

One of The Best Products for Damaged Hair

k18 is one of the best products in the market for damaged hair. If you have highlighted, double processed or heat styled hair, you need this product. Make sure to apply it on towel dry hair, not to use conditioner prior, and to wait the indicated time prior to proceeding with other products or styling. This doesn't replace protein treatments, other bond repair products or serums. K18 works in a totally different way to heal damaged hair and makes a great addition to your monthly hair routine.

0 people found this helpful

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LovelySkin Customer

Verified Purchase

February 01, 2024

Happy!

After following instructions I am now down to maintenance treatments. I do notice a difference in my hair after using product. I do follow with conditioner and am happy with the results.

0 people found this helpful

Profile picture of Skinlove.

Skinlove

Verified Purchase

January 31, 2024

Ease of Application

I like this product when I'm in a time crunch - I don't have to apply conditioner (in fact you aren't supposed to) and then I apply this. There is no waiting or applying to damp hair before showering that some other products require. It hasn't been life changing in terms of impact to my hair but my hair is relatively healthy but the ease of application is superb.

0 people found this helpful

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LovelySkin Customer

Verified Purchase

January 03, 2024

Love

I have dry and damaged hair, this product is making me like my poor hair again.

0 people found this helpful

Profile picture of Hurley.

Hurley

Verified Purchase

December 01, 2023

LOVE

This is the only hair repair treatment I’ve used that I’ve actually seen and felt a difference in my hair. Wish it came in a bigger size than 1.7 oz though.

2 people found this helpful



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