Jumbo leave in molecular repair hair mask

Mini, Full, and Jumbo size leave in molecular repair masks lined up next to each other on a pink background.

Grey curly hair before and after results using k18.

Red curly hair before and after results using k18.

Bleach blonde hair before and after results using k18.

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

Jumbo Leave-In Molecular Repair Hair Mask 100mL

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4.7

Rated 4.7 out of 5 stars

8,214 Reviews

jumbo leave-in molecular repair hair mask

Name: Jumbo Leave-In Molecular Repair Hair Mask 100mL
Brand: K18Hair
SKU: K18-31008
Price: 120.00 GBP
Availability: InStock

4-minute leave-in treatment - now in an exclusive jumbo size

Jumbo Leave-In Molecular Repair Hair Mask 100mL £120.00

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

PEPTIDE PREP™ detox shampoo

4.9

Rated 4.9 out of 5 stars

556 Reviews

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

Molecular repair hair oil

4.8

Rated 4.8 out of 5 stars

968 Reviews

Weightless oil that strengthens, repairs damage + reduces frizz

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 8,214 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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8,214 reviews

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Katrina C.
Verified Buyer
Reviewing
Mini Leave-In Molecular Repair Hair Mask 15 mL
I recommend this product
Rated 5 out of 5 stars
Yesterday
Excellent product
My hair due to bleaching, menopause and sun was so very dry and brittle. It felt like straw. So far I have only used K18 repair mask 3 times and I can already see the difference and my hair looks more shiny.
Was this helpful?
KU
K18Hair UK
4 minutes ago
Thank you for your wonderful review, Katrina! We're so thrilled to hear that the Mini Leave-In Molecular Repair Hair Mask is already making such a noticeable difference after just 3 uses. It sounds like your hair has been through a lot with bleaching, menopause, and sun exposure, so we're especially happy that K18 is helping restore that shine and improving the overall feel of your hair. Going from straw-like texture to healthier, shinier hair is exactly the kind of transformation we love to see! Thank you for choosing K18 and for taking the time to share your experience with us. ✨
Renee H.
Verified Buyer
Reviewing
Jumbo Leave-In Molecular Repair Hair Mask 100mL
I recommend this product
Age 45 - 54
Hair Concern Chemical damage, Frizz, Fragile/brittle hair, Dryness, Split-Ends
Hair Type Fine/Thin
My Results Less Frizz, Visible Difference, Smoother Hair, Shinier Hair
Rated 5 out of 5 stars
Yesterday
Awesome product
This product is a saving grace! After having a hair dresser have a tantrum and poured acid all over my hair and scalp K 18 has definitely helped! Great company and will continue to buy the products!
Was this helpful?
KU
K18Hair UK
Yesterday
Thank you so much, Renee! 💛 We're so sorry about your experience, but thrilled K18 has been able to help restore your hair. Your trust means everything to us! ✨
kelly b.
Verified Buyer
Reviewing
Leave-In Molecular Repair Hair Mask Sample
I recommend this product
Rated 5 out of 5 stars
2 days ago
Great product!
Wish it was easier to get out of the sample but otherwise great product
Was this helpful?
KU
K18Hair UK
2 days ago
Thank you so much for the 5 stars, Kelly! We're thrilled you love the Leave-In Molecular Repair Hair Mask and appreciate your feedback about the sample packaging.
Julia T.
Verified Buyer
Reviewing
Jumbo Leave-In Molecular Repair Hair Mask 100mL
I recommend this product
Age 25 - 34
Hair Concern Chemical damage, Heat damage, Fragile/brittle hair, Split-Ends, Oily hair/scalp
Hair Type Fine/Thin
My Results Visible Difference, Stronger Hair, Less Breakage
Rated 5 out of 5 stars
4 days ago
Absolutely favorite
I bought my first bottle at HongKong Sephora back in March. I wasn’t sure how good it’s gonna be since I was recommended by AI. I have thin/fine hair, and I bleach it to blonde every 3 months. I always had a hard time growing my hair long cause it’s so damaged. Nothing I tried worked!!!! Not even the products recommended by my hairstylist.
Was this helpful?
KU
K18Hair UK
4 days ago
Thank you so much, Julia! 💛 We're thrilled the Jumbo Leave-In helped where nothing else worked for your bleached hair. Your trust means everything to us! ✨
Shannon B.
Verified Buyer
Reviewing
Jumbo Leave-In Molecular Repair Hair Mask 100mL
I recommend this product
Age 35 - 44
Hair Concern Chemical damage, Heat damage, Frizz, Fragile/brittle hair, Dryness
Hair Type Fine/Thin
My Results Less Breakage
Rated 5 out of 5 stars
4 days ago
It worked
It seems to have made a difference in breakage
Was this helpful?
KU
K18Hair UK
4 days ago
Thank you for your wonderful review, Shannon! We're so thrilled to hear that the Jumbo Leave-In Molecular Repair Hair Mask is making a real difference in reducing breakage for you. That's exactly what we love to see - our molecular repair technology working to strengthen and protect your hair from the inside out.

It's so rewarding to know that K18 is helping improve the health of your hair. Thank you for choosing us and for taking the time to share your experience!