Leave-in molecular repair hair mask 50mL

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

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4.7

Rated 4.7 out of 5 stars

7,961 Reviews

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 Leave-In Molecular Repair Hair Mask 50mL £70.00

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

how to use

Shampoo, do not condition. Towel-dry thoroughly.
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.
Let sit for 4 minutes. Do not rinse out.
Comb, add product + style as usual. Use for 4-6 washes post-salon service, then as needed.

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.

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

Molecular repair hair oil

4.8

Rated 4.8 out of 5 stars

888 Reviews

Weightless oil that strengthens, repairs damage + reduces frizz

PEPTIDE PREP™ detox shampoo

4.9

Rated 4.9 out of 5 stars

510 Reviews

Color-safe, non-stripping clarifying shampoo with the K18PEPTIDE™

Description

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*

*k18hair.co.uk/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 coloUring 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. Most of the product leave my hair greasy and I can’t even style it, and right after washing I have to put it in the bun. It’s a nightmare! But not with k-18. 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

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.

feel what's possible with K18

See how K18 unlocks our community's expression

4.7

Rated 4.7 out of 5 stars

Based on 7,961 reviews

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7,961 reviews

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Erika R.
Verified Buyer
Reviewing
Leave-In Molecular Repair Hair Mask Sample
I recommend this product
Rated 5 out of 5 stars
Yesterday
Definitely helped my bleached hair!
It’s definitely helped my bleached hair. I’ll repeat the products!
Was this helpful?
KU
K18Hair UK
43 minutes ago
Thank you so much for your wonderful review, Erika! 💛 We're absolutely thrilled to hear that the Leave-In Molecular Repair Hair Mask Sample has definitely helped your bleached hair! ✨ It's amazing how molecular repair can make such a difference for damaged hair - that's exactly what we love to hear! We're so excited that you'll be repeating the products and can't wait for you to continue seeing those incredible results. Thanks for your fantastic 5-star review! 🙌
Dustin O.
Verified Buyer
Reviewing
Mini Leave-In Molecular Repair Hair Mask 15 mL
I recommend this product
Age 35 - 44
Hair Concern Chemical damage
Hair Type Fine/Thin
My Results Less Frizz, Visible Difference
Rated 5 out of 5 stars
Yesterday
Definitely worth the price paid!
Can see a definite difference in my hair after purchasing the mini sample box! I love this product and will be purchasing again!
Was this helpful?
KU
K18Hair UK
33 minutes ago
Thank you so much for your fantastic review, Dustin! 💛 We're absolutely thrilled to hear that you can see such a definite difference in your hair after using the AirWash from the sample box! We're so excited that you love the product and that you'll be purchasing again - that's exactly what we love to hear! Thanks for your wonderful 5-star review! 🙌
M G.
Verified Buyer
Reviewing
Mini Leave-In Molecular Repair Hair Mask 15 mL
I recommend this product
Rated 5 out of 5 stars
Yesterday
OMG! Holy grail!!
I can see why this product gets so much praise.
It’s definitely not an overnight rescue and people must follow the instructions to get the best results.
I personally use it differently but that’s what works for me.
I don’t have it on soaking hair but not on damp either I squeeze out the water and that’s it before applying just so I have enough slip to brush it through my hair
I find this works for me and I can use it easily compared to towel-dampened hair.
It has a very neutral smell and a little goes a long way - I personally started with 2 pumps per section (divided into 4) and have now reduced to 1 pump per section cuz I don’t feel I need the intensity of the treatment anymore cuz the results have been amazing.
I wait the 4 mins then I go cover with a conditioner THEN i rinse out and this is my preferred way of using it.
It takes a couple uses to see the full effect but after the second consecutive use my hair looks so much better. My curls clump better together, they look less limp and frizz has decreased MASSIVELY. my curls are always popping, I will show u some day 5 hair pictures. I’ve had the same styling combo for years but after introducing this product my hair styles last til the next week.
Noted my hair is VERY limp and brittle at the front, it used to just be straight but now it’s got a little wave :)
Where was this product all my life !!
It’s definitely worth the investment and I will continue to rave about this :)
Was this helpful?
KU
K18Hair UK
24 minutes ago
Thank you so much for this incredible review, M! 💛 We're absolutely thrilled to hear that you can see why K18 gets so much praise - and now you're adding to it with this amazing feedback! ✨

We love that you've found your own perfect routine with the Mini Leave-In Molecular Repair Hair Mask and that it's working so beautifully for you! It's fantastic that you've been able to adjust from 2 pumps to 1 pump per section as your hair has improved - that's exactly how molecular repair works, rebuilding your hair's strength over time.

We're so excited that this has become your holy grail and that you'll continue raving about it. Thanks for your wonderful 5-star review and for sharing your detailed routine - other customers will love hearing about your experience!
Penny K.
Verified Buyer
Reviewing
Mini Leave-In Molecular Repair Hair Mask 15 mL
I recommend this product
Rated 5 out of 5 stars
2 days ago
K18 - unreal !
From someone who normally uses half a bottle of conditioner on my frizzy dry damaged hair this concept of using such a small amount was crazy . Believe me … this product is amazing and you do only need a tiny bit . Follow the instructions and you will see the results soak for themselves . My hair never has been so good !
Was this helpful?
KU
K18Hair UK
1 hour ago
Thank you so much for your incredible review, Penny! 💛 We're absolutely thrilled to hear about your amazing transformation! It's so exciting that you've experienced firsthand how K18's molecular repair technology works - going from needing half a bottle of conditioner to just a tiny amount of our Mini Leave-In Molecular Repair Hair Mask is exactly the kind of game-changing results we love to hear about! ✨ Your frizzy, dry, damaged hair has never been so good, and that's the power of following the instructions and letting the molecular repair work its magic. We're so glad you're seeing the results speak for themselves! Thanks for your fantastic 5-star review! 🙌
Geneve H.
Verified Buyer
Reviewing
Full-Size Leave-In Molecular Repair Hair Mask 50mL
I recommend this product
Age 55 - 64
Hair Concern Heat damage
Hair Type Grey Hair, Medium Density, Fine/Thin, Curly/Coily
My Results Visible Difference, Less Frizz, Less Breakage
Rated 5 out of 5 stars
2 days ago
IT’S WORKING!
My hairdresser always educates and guides me for my hair care and never steers me wrong. Even with heat protection, I fried my hair pretty good, not to mention I moved from CA to CO and it’s very dry here and water is hard. I knew I would need more than three treatments as you will see in the picture, BUT it’s definitely noticeable. I’m still not putting heat to my hair to give it complete restoration. However, this is worth the money because it DEFINITELY is working. Thank you K18!
Was this helpful?
KU
K18Hair UK
1 hour ago
Geneve, we're so excited to hear about your progress! 🙌 It sounds like you've been through a lot with the move and environmental changes, but we're thrilled the Molecular Repair Mask is making such a noticeable difference already. Your hairdresser sounds amazing, and we love that you're being so patient with the restoration process by avoiding heat. Thank you for sharing your journey with us - results like yours are exactly why we do what we do! ✨💛