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K18

K18 Leave-In Molecular Repair Hair Mask, Patented, Lasting Repair For Dry, Frizzy, Damaged Hair, Reverse Damage In 4 Minutes From Bleach, Color, Chemical Services + Heat

  • Based on 31,200 reviews
Condition: New
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Availability: Only 10 left in stock, order soon!
Fulfilled by Amazon
Arrives Wednesday, Aug 19
Order within 20 hours and 36 minutes
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Size: 50 ml


Features

  • 4-Minute Molecular Hair Repair Treatment: A leave-in peptide hair mask designed to repair and reverse damage at the molecular level for stronger, smoother, more resilient hair in just 4 minutes.
  • How It Works: Patented K18PEPTIDE repairs hair at a molecular level to reverse damage from bleach, color, chemical services, and heat*. The biotech-developed peptide mimics and clicks into hair's keratin structure to reconnect polypeptide chains and disulfide bonds for strength along the length + width of hair.
  • Works on All Hair Types: Because our hair treatment works at the innermost layer of the hair rather than only targeting the outer cuticle like many deep conditioning hair masks, it's effective on all strands, even coily and curly hair.
  • Boosts Strength + Smoothness: Helps improve texture, manageability, and bounce with a highly concentrated hair cream formula with detangling and softening benefits. Most see results after 2-3 uses.
  • How to Use: Shampoo, skip conditioner, and apply 1-3 pumps of the leave in hair mask to clean, towel-dried hair. Let sit for 4 minutes, do not rinse, then style as usual. Use for 4-6 consecutive washes, then as needed.

Description

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. 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. 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. 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. Molecular Repair Mask Molecular Repair Oil Damage Shield Shampoo Detox Shampoo Damage Shield Conditioner AirWash Dry Shampoo AstroLift Volume Spray

Product Dimensions ‏ : ‎ 1.87 x 1.87 x 4 inches; 3.2 ounces


Item model number ‏ : ‎ K18-31005


UPC ‏ : ‎


Manufacturer ‏ : ‎ K18


Best Sellers Rank: #82 in Beauty & Personal Care (See Top 100 in Beauty & Personal Care) #1 in Hair Treatment Masks


#1 in Hair Treatment Masks:


Customer Reviews: 4.3 4.3 out of 5 stars (31,200)


Item Form: Cream


Hair Type: Damaged


Product Benefits: "Real, lasting repair powered by K18PEPTIDE™ Hair like new in 4 minutes* Soft, strong, bouncy hair for everyone "


Additional Features: Travel Size


Package Type Name: Jar


Hair Conditioner Type: Leave-In Hair Conditioner


Unit Count: 1.7 Fluid Ounces


Number of Items: 1


Item Dimensions: 1.87 x 1.87 x 4 inches


Liquid Volume: 50 ml


Item Weight: 3.2 ounces


Size: 50 ml


Brand Name: K18


Age Range Description: Adult


Manufacturer: K18


UPC: 858511001029 858511001128 729162271362 729162270877 755801147958 726929222179 729162271317 729162271249 729162271096


Global Trade Identification Number: 28


Model Number: K18-31005


Manufacturer Part Number: K18-31005


Material Features: Natural


Active Ingredients: Water (Aqua) (Eau), Alcohol Denat., PropyleneGlycol, Cetearyl Alcohol, Dicaprylyl Ether, Cetyl Esters, BehentrimoniumChloride, Polysorbate 20, sh-Oligopeptide-78, Hydrolyzed Wheat Protein,Hydrolyzed Wheat Starch, Isopropyl Alcohol, Tocopherol, Phenoxyethanol,Potassium Sorbate, Citric Acid, Fragrance (Parfum), Geraniol, Linalool, HexylCinnamal, Benzyl Alcohol.


Recommended Uses For Product: Shampoo, skip conditioner. Towel-dry thoroughly. Apply 1-3 pumps from ends to roots (3-9 pumps for 15ml sized mask). Less is more. Wait 4 minutes, do not rinse.


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Wednesday, Aug 19

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Similar Products

Top Amazon Reviews

    • OMG! OMG ! OMG! K-18 FULFILLS ITS CLAIMS Read on!
Size: 0.51 Fl Oz (Pack of 1)
I’m over 55 and have spent decades trying everything — from $9 to $144 per product — hoping for softer, healthier hair. I have 3a curls hidden under years of color, heat damage, and dryness. My hair would break and frizz so badly it looked like I had layers (I don’t). K18 is the first and only product that actually delivered on its promise to repair — not just coat — my hair. I was fully prepared to return this if it did not make a difference. It did. This isn’t a conditioner or mask. K18 uses a patented technology that works from the inside out. I used a clarifying shampoo, applied 6 pumps (very small pumps from the "try it" bottle!), finger-raked it through damp hair, waited 4 minutes, and then combed through. No rinsing, no other products. I let my hair air-dry, and it already felt softer and smoother with significantly less frizz. No fragrance -makes me happy. Important note: You do not need to rub this aggressively between your palms to "activate" it — that’s a common myth. Just rub your palms lightly so you can apply it evenly and let the science do the work. It works on the keratin molecules to repair your hair from the inside out. Friction is not going to make the molecules smaller. Don't know why people start these rumors. The next morning, I used my straightener on medium heat and was stunned. Instead of the usual dry straw, my hair was sleek, shiny, and bouncy. Even the ends curled beautifully — something I’ve never seen on my hair before. After four treatments, my hair now feels different, although the greatest results came after the very first use. My hair is softer, smoother, more manageable, with less frizz and more shine. Even in Florida’s 90°+ heat and humidity, it holds up — and I’m not using anything else but K18. A friend even asked to try it after seeing my results. It’s expensive, but absolutely worth it. I’ve already bought the larger bottle. I’m sticking with K18 — this changed everything for me. And to address the expense, the 50mL pump provides 50 pumps. That's 25 applications for me. My average thickness, long hair uses 2 full regular pumps. After the first 4 applications, you move to every 4 washes. That means after the first four treatments, I have 21 treatments more still in the pump bottle. For me, with super dry hair, that means it will last another 18-21 weeks since I only wash once a week, and an occasional "extra". I am going to guess I have taken at least $100 of products that did not work for me to the women's shelter over that time, meaning the waste was as much as this effective product that takes no time to use, packs easily in a suitcase, doesn't stink and IT WORKS! If you have super straight, silky hair, like Asian hair, or other non-porous hair, I do not think you are going to get the same results. You probably already have the kind of hair those of us with porous, damaged hair are looking for. Ask ChatGPT ... show more
Reviewed in the United States on June 25, 2025 by GG
    • Amazing Repair from the First Use!
Size: 0.51 Fl Oz (Pack of 1)
Review Image by Karlas Villavicencio
Review Image by Karlas Villavicencio
I tried the K18 Leave-In Molecular Repair Hair Mask after getting highlights, and the difference was incredible. After just one use, my hair felt much softer, stronger, and had significantly less frizz. I also loved that it didn’t leave my hair feeling heavy or greasy. Instead, it made my hair look healthier and shinier. You only need a small amount, so even though the bottle is small, it lasts a long time. If your hair is damaged from bleaching, coloring, or heat styling, this product is definitely worth trying. I highly recommend it! ⭐⭐⭐⭐⭐ ... show more
Reviewed in the United States on July 30, 2026 by Karlas Villavicencio
    • Absolutely Worth the Hype
Size: 50 ml
Review Image by Michelle
I’ve tried a lot of hair products over the years, and K18 is one of the few that actually lived up to its promises. After just a few uses, my hair felt noticeably softer, smoother, and much stronger. It helped reduce frizz, made my hair easier to brush, and gave it a healthier look without weighing it down. A little goes a long way, so the bottle lasts longer than I expected. I especially noticed a difference on my dry, damaged ends from heat styling and coloring. My hair looks shinier, feels healthier, and doesn’t break as easily. The price is definitely higher than most hair products, but because you only need a small amount and it actually works, I think it’s worth the investment. If your hair is damaged, overprocessed, or just needs some extra care, I highly recommend giving K18 a try. ... show more
Reviewed in the United States on July 10, 2026 by Michelle
    • Miracle Product For Me!
Size: 50 ml
This product has been like a miracle for my hair. I have fine, colored hair that could tend to be dry and brittle if I let it. Also, most products would make my hair feel "weighty" when styled. This product is so moisturizing, but like you have nothing on your hair at the same time. I've been using K18 for well over a year now and I get so many people asking me how I keep my hair so healthy at age 66. It just gives it a silky feel with a lot of movement. Best discovery ever. ... show more
Reviewed in the United States on July 28, 2026 by Sharon Helton
    • Great Results, but a Bit Pricey
Size: 0.51 Fl Oz (Pack of 1)
Review Image by The Marnie Edit ✨
Review Image by The Marnie Edit ✨
Review Image by The Marnie Edit ✨
I’ve been using the K18 Leave-In Molecular Repair Hair Mask on my color-treated and damaged hair, and I’ve noticed a real improvement in how soft and healthy it feels. My hair looks smoother, feels stronger, and has less frizz after using it consistently. I also like that it’s lightweight and doesn’t leave my hair greasy or weighed down. The application is simple, and since only a small amount is needed, a little product goes a long way. It works especially well when following the instructions and using it as part of a regular hair care routine.The only reason I’m giving it four stars instead of five is the price. While the product performs well, it is expensive for the amount you receive, so it may not fit everyone’s budget.Overall, I think it’s a high-quality treatment that delivers noticeable results, especially for damaged or chemically treated hair. If you’re willing to invest in your hair care, it’s definitely worth trying. ... show more
Reviewed in the United States on July 13, 2026 by The Marnie Edit ✨
    • K18 really works
Size: 0.51 Fl Oz (Pack of 1)
This stuff really works. My hair is badly damaged from constance high lights and thinning terribly. I have washed and used twice I can definitely tell a difference. It is expensive I only bought the 29 dollar bottle to try. I will be getting the larger bottle next time..
Reviewed in the United States on July 31, 2026 by Virginia morgan
    • This is a miracle must have product to revive processed hair
Size: 0.51 Fl Oz (Pack of 1)
Review Image by ✨beautyhealthfitness✨
K18 is a necessity for compromised colored/lightened hair - it's worth the investment. It's a miracle product on processed hair it moisturizes, smooths frizz, makes hair soft again, adds natural shine and makes hair manageable again. Has a light fragrance and a little goes a long way if you use the product correctly. *Read and make sure to follow the directions on the box - need to really emulsify it into a cream in your hands prior to working it through your hair. ... show more
Reviewed in the United States on July 25, 2026 by ✨beautyhealthfitness✨
    • A little pricey for the size but definitely works.
Because of the high price I was reluctant to purchase this. But with all the hype and the fact that my granddaughters thick, beautiful curls desperately needed something that would redefine them and calm the frizz. I made the purchase. I’m so glad I did. The smell alone is almost worth the price, just wow. Smells amazing. We’ve tried so many other products but I have to say if I could afford it, this is the only one we’d be using on a regular basis. I purchased the detox shampoo and leave in oil to use as a three step system and it’s like magic. This is a pretty small bottle but we’re getting quite a few uses out of it. Once it’s gone I’ll use her other products but I’ll always repurchase this like every other month just to keep those curls in check. Reason for taking off one star is because of small size considering the higher price. It really works though so I’d recommend it. ... show more
Reviewed in the United States on June 20, 2026 by StephJ

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