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K18 Leave-In Molecular Hair Mask, Repairs Dry or Damaged Hair, Reverse Hair Damage from Bleach, Color, Chemical Services & Heat
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Return this item for free
We offer easy, convenient returns with at least one free return option: no shipping charges. All returns must comply with our returns policy.
Learn more about free returns.- Go to your orders and start the return
- Select your preferred free shipping option
- Drop off and leave!
Bundles with this item
Purchase options and add-ons
Brand | K18 |
Item Form | Cream |
Material Feature | Natural |
Hair Type | Damaged |
Product Benefits | Our K18PEPTIDE™ repairs hair at a molecular level across multiple types of bonds, restoring hair health for all See more |
Additional Details


Description
Benefits
Suggested use
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- Sustainability features for this product
Sustainability features
This product has sustainability features recognized by trusted certifications.Manufacturing practicesManufactured using processes that reduce the risk of negative environmental impact.As certified byCradle to Cradle Certified is the world's most comprehensive standard for safe, circular and responsible products. Certified products meet science-based requirements that have positive benefits including health and wellbeing, material reuse, emissions reductions, water quality, and fair and safe labor practices. The Cradle to Cradle Certified Product Standard is set by the Cradle to Cradle Products Innovation Institute, a global non-profit dedicated to powering innovation for a prosperous economy.Certification LevelSILVER ACHIEVEMENT LEVELWorker well-beingManufactured on farms or in facilities that protect the rights and/or health of workers.As certified byCradle to Cradle Certified
Cradle to Cradle Certified is the world's most comprehensive standard for safe, circular and responsible products. Certified products meet science-based requirements that have positive benefits including health and wellbeing, material reuse, emissions reductions, water quality, and fair and safe labor practices. The Cradle to Cradle Certified Product Standard is set by the Cradle to Cradle Products Innovation Institute, a global non-profit dedicated to powering innovation for a prosperous economy.Certification LevelSILVER ACHIEVEMENT LEVELSafer chemicalsMade with chemicals safer for human health and the environment.As certified byCradle to Cradle Certified
Cradle to Cradle Certified is the world's most comprehensive standard for safe, circular and responsible products. Certified products meet science-based requirements that have positive benefits including health and wellbeing, material reuse, emissions reductions, water quality, and fair and safe labor practices. The Cradle to Cradle Certified Product Standard is set by the Cradle to Cradle Products Innovation Institute, a global non-profit dedicated to powering innovation for a prosperous economy.Certification LevelSILVER ACHIEVEMENT LEVEL - Sustainability features for this product
Sustainability features
This product has sustainability features recognized by trusted certifications.Safer chemicalsMade with chemicals safer for human health and the environment.As certified byCradle to Cradle Certified
Cradle to Cradle Certified is the world's most comprehensive standard for safe, circular and responsible products. Certified products meet science-based requirements that have positive benefits including health and wellbeing, material reuse, emissions reductions, water quality, and fair and safe labor practices. The Cradle to Cradle Certified Product Standard is set by the Cradle to Cradle Products Innovation Institute, a global non-profit dedicated to powering innovation for a prosperous economy.Certification LevelSILVER ACHIEVEMENT LEVELWorker well-beingManufactured on farms or in facilities that protect the rights and/or health of workers.As certified byCradle to Cradle Certified
Cradle to Cradle Certified is the world's most comprehensive standard for safe, circular and responsible products. Certified products meet science-based requirements that have positive benefits including health and wellbeing, material reuse, emissions reductions, water quality, and fair and safe labor practices. The Cradle to Cradle Certified Product Standard is set by the Cradle to Cradle Products Innovation Institute, a global non-profit dedicated to powering innovation for a prosperous economy.Certification LevelSILVER ACHIEVEMENT LEVELManufacturing practicesManufactured using processes that reduce the risk of negative environmental impact.As certified byCradle to Cradle Certified
Cradle to Cradle Certified is the world's most comprehensive standard for safe, circular and responsible products. Certified products meet science-based requirements that have positive benefits including health and wellbeing, material reuse, emissions reductions, water quality, and fair and safe labor practices. The Cradle to Cradle Certified Product Standard is set by the Cradle to Cradle Products Innovation Institute, a global non-profit dedicated to powering innovation for a prosperous economy.Certification LevelSILVER ACHIEVEMENT LEVEL
From the brand

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Product Description



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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.
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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.
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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.
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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.
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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.
Shop the K18 Collection
![]() Molecular Repair Mask | ![]() Molecular Repair Oil | ![]() Damage Shield Shampoo | ![]() Detox Shampoo | ![]() Damage Shield Conditioner | ![]() AirWash | |
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Customer Reviews
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4.3 out of 5 stars 22,769
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4.4 out of 5 stars 1,341
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4.5 out of 5 stars 553
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4.6 out of 5 stars 1,451
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4.5 out of 5 stars 613
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4.2 out of 5 stars 244
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Price
| $75.00$75.00 | $65.00$65.00 | $36.00$36.00 | $38.00$38.00 | $36.00$36.00 | $48.00$48.00 |
Molecular Repair
| ✔ | ✔ | ✘ | ✘ | ✘ | ✘ |
Maintenance Routine
| ✘ | ✘ | ✔ | ✘ | ✔ | ✔ |
Treatment Routine
| ✔ | ✔ | ✘ | ✔ | ✘ | ✘ |
Used By Professionals
| ✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
At Home Use
| ✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
Product details
- Product Dimensions : 1.9 x 1.9 x 4 inches; 3.2 ounces
- Item model number : K18-31005
- UPC : 858511001029 858511001128 729162271362 729162270877 755801147958 726929222179 729162271317 729162271249 729162271096
- Manufacturer : K18
- ASIN : B0961ZS96M
- Country of Origin : USA
- Best Sellers Rank: #236 in Beauty & Personal Care (See Top 100 in Beauty & Personal Care)
- #3 in Hair Treatment Masks
- Customer Reviews:
Videos
Videos for this product
0:19
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A hair steamer keeps my curls moisturized and strong@TimelesslyMirna
Videos for this product
2:11
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Do you have bad ends like me? WATCH TILL THE ENDFruit of Her House
Videos for this product
2:36
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How to use k18 on thick, coarse, dry hairWhy Reviews
Videos for this product
1:14
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A before and after of this repairing hair maskCassie Lord
Videos for this product
1:44
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K18 peptide for strengthening and repairing hairGeri Terranova
Videos for this product
1:22
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The good and bad about this Hair MaskCallie Ammons 🔵
Customer reviews
Customer Reviews, including Product Star Ratings help customers to learn more about the product and decide whether it is the right product for them.
To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyzed reviews to verify trustworthiness.
Learn more how customers reviews work on AmazonCustomers say
Customers find the hair mask highly effective, with their hair becoming softer, smoother, and shinier. The product receives mixed feedback regarding hair repair and strength - while some report it helped heal over-processed bleached hair and stopped breakage, others say it didn't improve their hair quality and became brittle over time. The bottle size is consistently criticized for being too small for the price, and customers find the product pricey.
AI-generated from the text of customer reviews
Customers find the hair mask works well, with one noting that the results improve with continued use.
"...My hair feels soft, is nice and shiny and there is no frizz. It is light weight and smells good...." Read more
"...First of all, it’s simple to use. But more importantly, the results are fantastic! It has no strong smell and it doesn’t weigh my hair down...." Read more
"...It’s lightweight but highly effective, and I love how it repairs my hair without weighing it down...." Read more
"...The formula is super easy to apply, and a little goes a long way. I’ve noticed my hair feeling softer, looking shinier, and overall much healthier...." Read more
Customers report that the hair mask makes their hair softer and more manageable, with one customer noting it feels like silk, while others describe it as frizz-free and sleeker overall.
"...I used it this morning after my shower and it really does work. My hair feels soft, is nice and shiny and there is no frizz...." Read more
"...It has no strong smell and it doesn’t weigh my hair down. My hair is smooth and shiny and even has more volume. It looks so healthy and “younger”...." Read more
"...I’ve used it multiple times before, and each time my hair feels softer, stronger, and healthier...." Read more
"...The breakage has dramatically reduced, and the texture has improved—my hair feels stronger and more manageable...." Read more
Customers report that the hair mask makes their strands look shinier and healthier, with one customer noting that their hair has maintained this appearance for six months.
"...My hair feels soft, is nice and shiny and there is no frizz. It is light weight and smells good...." Read more
"...My hair is smooth and shiny and even has more volume. It looks so healthy and “younger”...." Read more
"...I’ve noticed my hair feeling softer, looking shinier, and overall much healthier...." Read more
"...feel thick or greasy but it just made my hair feel and look soft, shiny and healthy...." Read more
Customers have mixed experiences with the hair mask's repair capabilities, with some reporting that it helped revive their hair and saved it, while others found it did not improve their hair quality or was not healthy for their strands.
"...lightweight but highly effective, and I love how it repairs my hair without weighing it down...." Read more
"Went from box dark brown neutral dye, to blonde in one sitting. Damage was present. I walked out with bangs! HAHA...." Read more
"I cannot rave enough about the K18 Hair Mask—it has truly saved my hair! I used to pull my hair every day, causing so much damage and breakage...." Read more
"...The K18 has helped with the damage, added shine back to my hair, and lessened the amount of hair that falls out...." Read more
Customers have mixed experiences with the hair mask's strength, with some reporting that their hair becomes stronger and breakage stops, while others note that their hair becomes brittle over time.
"...used it multiple times before, and each time my hair feels softer, stronger, and healthier...." Read more
"...2 more rounds to get my normal hair back because it was very very damaged from the relaxer. Never again y’all. Never again!..." Read more
"...The breakage has dramatically reduced, and the texture has improved—my hair feels stronger and more manageable...." Read more
"...It shortens my shower time, extends the life of my conditioner, makes brushing my hair effortless, and leaves my hair looking healthy once..." Read more
Customers have mixed experiences with the hair mask's effect on dryness, with some finding it helps with dryness and frizz while others report it makes their hair super dry.
"...Second time trying it, it just left my hair dry...." Read more
"...I applied more than suggested and still, my hair soaked it up...." Read more
"...It was just dry and frizzy...." Read more
"...my next lift session in a couple weeks and this product instantly bought moisture and softness back into my hair...." Read more
Customers find the hair mask expensive, with several noting that the bottle size doesn't justify the price.
"...It is a little pricey to me but it seems to be worth it...." Read more
"...It looks so healthy and “younger”. It’s expensive, but I think I’m going to have to make room for it in my beauty budget!..." Read more
"Expensive but so worth it if you have chemically treated or bleached hair...." Read more
"...It’s well worth the investment, and my hair has never looked or felt better. Highly recommend!" Read more
Customers find the bottle size of the hair mask too small, particularly noting that it doesn't provide enough product for shoulder-length hair.
"Yes, the bottle is TINY. However, I noticed a difference after one use!..." Read more
"...The brand's bundles are a nice idea but again, the high cost and dismal size of the product received do not match up...." Read more
"...It shortens my shower time, extends the life of my conditioner, makes brushing my hair effortless, and leaves my hair looking healthy once..." Read more
"very good product, but the packaging is REALLY small for such an expensive product but next time i buy i’ll get the bigger size...." Read more
Reviews with images

Blondes have More Fun Until They Fry Their Hair
Top reviews from the United States
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- Reviewed in the United States on April 5, 2025Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseLives up to the hype. I've heard a lot about K18 but was skeptical. It's getting warmer and more humid where I live and my hair gets frizzy in high humidity so I thought I'd give this a try. I used it this morning after my shower and it really does work. My hair feels soft, is nice and shiny and there is no frizz. It is light weight and smells good. I only used 4 pumps on my hair that is just above shoulder length. It is a little pricey to me but it seems to be worth it. I will likely buy this again - but maybe I'll just use it in the summer when my hair gets frizzy.
- Reviewed in the United States on April 14, 2025Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseI was honestly kind of expecting this to be one of those TikTok-viral, snake oil products. But my hair has become less shiny and healthy as I’ve aged (I’m 57) and it has recently started to break off. I did a google search and found this product and decided to give it a try. I’m so pleasantly surprised! First of all, it’s simple to use. But more importantly, the results are fantastic! It has no strong smell and it doesn’t weigh my hair down. My hair is smooth and shiny and even has more volume. It looks so healthy and “younger”. It’s expensive, but I think I’m going to have to make room for it in my beauty budget! You don’t use regular conditioner when you use this product, so that will help offset the cost (because my regular conditioner is expensive too).
- Reviewed in the United States on April 4, 2025Size: 50 mlVerified PurchaseThe K18 Molecular Repair Hair Mask is by far my favorite K18 product. I’ve used it multiple times before, and each time my hair feels softer, stronger, and healthier. It’s lightweight but highly effective, and I love how it repairs my hair without weighing it down. The Detox Shampoo and Molecular Repair Hair Mask are the only ones that really worked for my hair.
Unfortunately, the regular shampoo, conditioner, and oil didn’t work for me—they left my hair dull and dry. But these two are worth the hype and have earned a spot in my routine.
- Reviewed in the United States on December 31, 2024Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseI cannot rave enough about the K18 Hair Mask—it has truly saved my hair! I used to pull my hair every day, causing so much damage and breakage. My hair was dry, brittle, and lacked any real shine or strength. After using this mask for a few weeks, the difference is incredible.
The formula is super easy to apply, and a little goes a long way. I’ve noticed my hair feeling softer, looking shinier, and overall much healthier. The breakage has dramatically reduced, and the texture has improved—my hair feels stronger and more manageable. It’s as if the mask has repaired the damage I caused over time.
I now look forward to hair care days because I can actually feel and see the difference. If your hair has been through a lot, this mask is a game-changer! It’s well worth the investment, and my hair has never looked or felt better. Highly recommend!
- Reviewed in the United States on April 13, 2025Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseExpensive but so worth it if you have chemically treated or bleached hair. I was worried it would feel thick or greasy but it just made my hair feel and look soft, shiny and healthy. Super easy to apply and light weight while being deeply nourishing. I applied more than suggested and still, my hair soaked it up. My hair stylist actually commented on how healthy my hair felt recently and I attribute it entirely to k18
- Reviewed in the United States on April 1, 2025Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseIt is pricey but effective. The first time I used it, I was confused because it doesn’t feel effective right away. But WOW it made a huge difference in my hair, which is super damaged from both years of bleach and also a perm. My hair is less frizzy, softer, and more manageable when I use this. I did shampoo only, no conditioner. Then the K18. At that point my hair is already feeling good. If I add a tiny bit of oil, it is absolutely perfect. Feels like I never abused it. 10/10
- Reviewed in the United States on October 7, 2024Size: 50 mlVerified PurchaseI fell in love with the K18 Leave-In Molecular Hair Mask about a year ago after my hairdresser introduced me to it. While it’s on the pricier side, its effectiveness and quality make it worth every penny. When I’m unable to splurge, I turn to my regular leave-in spray, Perfect 10 Lite.
As someone with thin, color-treated hair that tangles easily and suffers from damage, this product has been a game changer. It shortens my shower time, extends the life of my conditioner, makes brushing my hair effortless, and leaves my hair looking healthy once styled.
I recently purchased the larger size, fully aware of the cost. However, when I opened my package, I briefly thought I either ordered the smaller size by mistake or received the wrong item. I realized it was indeed the larger size I ordered and I debated returning it.
The true test came when I woke up with a legit rat's nest. I was so thankful I had this product on hand, as it made detangling much easier than previous times when I had nothing to help with the mess.
One note: I read a review suggesting that you should rub the product between your palms to activate it before applying it to your hair. That makes sense, and I’ll definitely give it a try. However, I find it quite unethical that the company leaves this step out of the instructions on the box and bottle. It feels like they might not want you to use it correctly so that you’ll need to buy more sooner—quite disappointing!
- Reviewed in the United States on March 22, 2025Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseYes, the bottle is TINY. However, I noticed a difference after one use!
It says to skip conditioner, use the K18, wait 5 minutes, then add your hair products and style as usual. But with as thick as my hair is, I don’t skip conditioner.
I’ve been blonde for years and went back to my black roots. Used black box dye to cover up the random grays that would come through and got tired of that so started going back lighter. I got balayage and it ruined my hair. Tbh I don’t think the hair stylist knew what she was doing but that’s besides the point. My hair was falling out in huge clumps through out the day and when washing and brushing. The K18 has helped with the damage, added shine back to my hair, and lessened the amount of hair that falls out.
There’s not much of a scent to the product. It’s light weight. I use more than 4 pumps too. I use about 8-10 pumps. My hair is THICK and half way down my back length wise. I use this once a week and so far it’s been almost a month and I still have plenty left in the bottle. It’s worth a try if your hair is damaged from bleach 👌🏼
Top reviews from other countries
- Maram AlmilhimReviewed in Saudi Arabia on November 3, 2024
5.0 out of 5 stars Love it
Size: 0.51 Fl Oz (Pack of 1)Verified Purchase👍🏻
- StellaReviewed in Sweden on February 15, 2025
4.0 out of 5 stars Good but tiny
Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseStellaGood but tiny
Reviewed in Sweden on February 15, 2025
Images in this review
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GabiReviewed in Spain on August 29, 2024
5.0 out of 5 stars Buen funcionamiento
Size: 50 mlVerified PurchaseTextura ligera, un pequeño pump da para media melena. Ideal para mantener pelo seco, estropeado o dañado. Leer bien el funcionamiento y el proceso. El olor podría mejorar, huele a químico. Percepción personal.
- KPReviewed in Canada on February 23, 2025
5.0 out of 5 stars Great product
Size: 50 mlVerified PurchaseMy hair was very damaged and whole this product is fairly pricey I felt that it really helped repair my damaged hair
- SafReviewed in the Netherlands on July 24, 2024
1.0 out of 5 stars Fake!!! Do not buy
Size: 0.51 Fl Oz (Pack of 1)Verified PurchaseThis is a fake. There are certain ways to check by the packaging if it is the real k18. Do your research. I thought the price seemed too good to be true. Well, it is!