Full-Size Leave-In Molecular Repair Hair Mask 50mL

£70

Full-Size Leave-In Molecular Repair Hair Mask 50mL

Grey curly hair before and after results using k18.

Bleach blonde hair before and after results using k18.

Red curly hair before and after results using k18.

get stronger, more resilient hair. left - 8x bleach without K18, right 8x bleach with K18

Mini versus full size product comparison

4.7

Rated 4.7 out of 5 stars

8,716 Reviews

bestseller

full-size leave-in molecular repair hair mask

Name: Full-Size Leave-In Molecular Repair Hair Mask 50mL
Brand: K18Hair
SKU: K18-31005
Price: 70.00 GBP
Availability: InStock

4-minute leave-in treatment to reverse hair damage

Full Size - 50 mL£70.00 Jumbo Size - 100 mL£120.00 Mini Size - 15 mL£30.00

£70

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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

- ingredients
  
  Water (Aqua) (Eau), Alcohol Denat., Propylene Glycol, Cetearyl Alcohol, Dicaprylyl Ether, Cetyl Esters, Behentrimonium Chloride, Polysorbate 20, sh- Oligopeptide-78, Hydrolyzed Wheat Protein, Hydrolyzed Wheat Starch, Isopropyl Alcohol, Tocopherol, Phenoxyethanol, Potassium Sorbate, Citric Acid, Fragrance (Parfum), Geraniol, Linalool, Hexyl Cinnamal, Benzyl Alcohol, Amyl Salicylate, Benzaldehyde.
- 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.
- 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.
- 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.
- 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.

pairs well with

Clarify. for less frequent heavy duty washing. just one wash removes 99% of product buildup*, 95% of sebum*, and 76% of copper*. Formulated with K18PEPTIDE™.

PEPTIDE PREP™ detox shampoo

FutureIQ™ biomimetic hair longevity serum

got questions?

still have questions? visit our help center

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.

soft, strong, bouncy hair for everyone

Repair damage for hair like new* in 4 minutes.

before

after

"I absolutely love this product!! You have to see it to believe it!"

- Christina Marie P.

before

after

“…I had my hair chopped (it was begging for it) along with some highlights and coloring of the roots. My hair stylist used this on my hair and I absolutely loved how it made my hair feel ... I love this mask so much!”

- Ashley P.

before

after

"Amazing the way it feels and the shine provides to the hair instantly."

- Sandra M.

before

after

"I’ve been using this mask for about four washes so far. I feel that my hair is getting healthier."

- Olga S.

before

after

"It makes my hair so soft and weightless, I absolutely love it... Makes my hair feel so luxurious, it’s like I just left the salon. Can’t recommend this product more!"

- Anastasiia T.

before

after

"My hair has been a mess for years... My new hair stylist recommended K18! ... My hair looks and feels amazing with lasting results!!"

- Arnell M

before

after

"I have heat damaged color treated curly hair and this has improved my hair health immensely...This is one of those products that has incorporated itself into my routine for the rest of my life..."

- Siria A.

powered by K18PEPTIDE™

Biomimetic peptide clicks into hair’s keratin structure—the source of core strength—for soft, shiny, bouncy results that won’t wash away.

Explore the Science

how to use molecular repair mask

1. Shampoo, do not condition. Towel-dry thoroughly.

2. Apply 1-3 pumps 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 styling product + style as usual. Use for 4-6 washes, then as needed.

*k18hair.com/disclaimers

learn more on our blog

October 24, 2024 / products

How much leave-in mask do you *really* need?

Find your optimal dose with this easy guide.

March 23, 2023 / hair science

The Science Behind K18 Molecular Repair

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December 08, 2024 / products

The Top K18 Mask FAQs

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4.7

Rated 4.7 out of 5 stars

Based on 8,716 reviews

93%would recommend these products

Reviews Summary

Customers say this hair mask transforms damaged, bleached, and chemically-treated hair, making it softer, stronger, and more manageable. Many report significant improvements in hair texture, with reduced breakage, split ends, and frizz. Users with curly hair find it enhances curl definition and reduces dryness. The lightweight formula doesn't weigh hair down or leave residue. Many reviews mention it works particularly well for bleached hair, helping restore smoothness and shine. Some note the price is high but find it worthwhile since only small amounts are needed per use.

Customers Talked About

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8,716 reviews

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frances d.
Verified Buyer
Reviewing
Leave-In Molecular Repair Hair Mask Sample
I recommend this product
Rated 5 out of 5 stars
4 minutes ago
Gold Standard!
This was the first K18 hair product that I ever used!
Have been a huge fan ever since. Every person I’ve gifted, loved instantly!
Was this helpful?
Mrs C. l. y. A.
Verified Buyer
Reviewing
Leave-In Molecular Repair Hair Mask Sample
I recommend this product
Rated 5 out of 5 stars
21 minutes ago
Leave in Molecular repair mask
Was a bit sceptical of this at first. Wondering how can it repair my hair. I was totally shocked, not only did it soften, smooth and leave my healthy, it's made it more manageable.
Am now using the full K18 range once a week.
Was this helpful?
Leah W.
Verified Buyer
Reviewing
Mini Leave-In Molecular Repair Hair Mask 15 mL
I recommend this product
Age 25 - 34
Hair Concern Chemical damage, Color-care, Frizz, Split-Ends
Hair Type Medium Density, Curly/Coily
My Results Smoother Hair, Shinier Hair, Less Frizz, Defined Curl/Wave Pattern
Rated 5 out of 5 stars
9 hours ago
Great Product
I use this with on alternate weeks with Olaplex. Really notice a differenxe
Was this helpful?
KU
K18Hair UK
8 hours ago
Thank you so much for your amazing review! 💙 We're thrilled to hear you're noticing a real difference with our Mini Leave-In Molecular Repair Hair Mask. We love being part of your haircare routine! ✨
Jane C.
Verified Buyer
Reviewing
Full-Size Leave-In Molecular Repair Hair Mask 50mL
I recommend this product
Rated 5 out of 5 stars
11 hours ago
K18
I have very fine damaged hair have used k18 for 4 hair washes and have seen a huge improvement can’t believe the difference very happy
Was this helpful?
KU
K18Hair UK
11 hours ago
Thank you so much, Jane! 💗 We're absolutely thrilled to hear that you're already seeing such a huge improvement in your hair after just 4 washes! It's amazing what our Molecular Repair Hair Mask can do, and we're so happy you're loving the difference. We can't wait for you to see even more results! ✨
bess b.
Verified Buyer
Reviewing
Mini Leave-In Molecular Repair Hair Mask 15 mL
I recommend this product
Age 55 - 64
Hair Concern Fragile/brittle hair, Dryness, Split-Ends
Hair Type Thick/Coarse
My Results Smoother Hair, Soft Touchable Hair, Less Frizz
Rated 5 out of 5 stars
13 hours ago
Great stuff!!
I haven’t used it long, but my hair is already starting to feel it look healthier
Was this helpful?
KU
K18Hair UK
11 hours ago
Thank you so much for your amazing review! 💙 We're thrilled to hear that the Mini Leave-In Molecular Repair Hair Mask is already making a difference for your hair. ✨

*Disclaimers