K18 Leave-In Molecular Hair Mask review: Why I'll never use another hair mask again

K18 Leave-In Molecular Repair Hair Mask (Photo via Sephora)
K18 Leave-In Molecular Repair Hair Mask before and after (Photo via Sephora)

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There's no doubt that a healthy diet, heat protectant and a silk pillowcase are the holy grails when it comes to healthy, bouncy hair — but hair masks, like the K18 Leave-In Molecular Repair Hair Mask, are also a worthy MVP.

After moving to a much drier climate, the change in air was wreaking havoc on my skin, wardrobe and hair. As someone who gets their hair highlighted twice a year and goes to extensive measures to ensure hair health, I was on a mission to find a way to rescue my otherwise healthy hair from the static-inspiring, dry air of my new city.

Even after watching a copious amount of YouTube videos reviewing hair products and mass-polling friends and family for hair health tips, it wasn't until I visited my local Sephora and heard the praises of the K18 Leave-In Molecular Repair Hair Mask that I wondered where this mask had been all my life.

K18 Leave-In Molecular Repair Hair Mask

K18 Leave-In Molecular Repair Hair Mask (Photo via Sephora)
K18 Leave-In Molecular Repair Hair Mask (Photo via Sephora)

$89 CAD/$75 USD at Sephora

The details

Whether you're a hair health enthusiast or have put your strands to the test, the patented peptide technology of this mask reverses damage from chemical treatments, colouring, bleaching and heat, claiming to restore your hair's strength and bounce.

Vegan and cruelty free, the K18 Leave-In Molecular Repair Hair Mask uses patented technology to target problem areas to restore hair to its healthiest state. The patented K18 peptide is the perfect size and molecular structure to reach the deepest layers of the hair, re-connecting keratin chains that contribute to your hair's strength, smoothness and elasticity.

A bonus? The K18 Leave-In Molecular Repair Hair Mask has a soft floral scent, leaving your tresses smelling fresh with notes of jasmine and peony.

How to use it

For this hair mask, the treatment begins with your shower. Shampoo your hair as usual, but skip the conditioner, instead gently towel drying your hair after you shampoo. K18 works best when used on its own without any supplementary masks.

Once your hair is towel dried and slightly damp, apply one pump of product, working into the hair from tips to root. K18 recommends using 1-3 pumps depending on the length and density of your hair. As this formula is highly concentrated, the amount of product used may feel light compared to other hair masks.

Refrain from applying other products to your hair for at least four minutes — this is the activation time. After four minutes, you can continue with your remaining post-shower products. As stated, this mask doesn't need to be rinsed out.

It's recommended you use the product for the first four to six weeks following any major hair treatments. Then you can switch to maintenance mode, using the mask as needed.

K18 Leave-In Molecular Repair Hair Mask
K18 Leave-In Molecular Repair Hair Mask

$89 CAD/$75 USD at Sephora

My review — and what others are saying

I couldn't believe the change in my hair after the first use of this leave-in mask. It was smooth with tidy ends that looked as though I had a professional trim and blow out. Styling was easier than usual and my hair had a soft sheen.

Sephora shoppers also can't get enough of this vial hair mask.

"I really didn't have much hope for this product, but gave it a shot anyway. I've tried several other bond repair products that did next to nothing, but this is a wow product. My hair is long, thick and bleached to platinum blonde. I've noticed a huge difference in one use. My hair is softer, my waves came back and the frizziness is 75 per cent less," shares one reviewer.

"Ok. I had to leave a review for this. It has totally changed my hair’s health. I have bleached my hair five times in the past year and this has restored it. Completely," adds another.

With more than 2,800 reviews and 4.3 stars, reviewers like to remind new purchasers that it really is important to follow the instructions to get the full shine-boosting, frizz-busting results.

"I have dark brown hair that I bleach every six weeks. This saved my hair and cut out four different products. I know the negative reviews say it makes your hair feel gross but they used way too much product," says a shopper. "I have hair that's four inches past my shoulder and I only use one pump on each half of my hair. I don't put too much on my roots and I really work it in, and let it sit while I do my makeup."

"I used at least three times less product than usual. I didn't even have to heat style my hair to make it look nice. I'm amazed, I didn't use that much product... four pumps for my entire head of very thick hair," adds another. "I absolutely love this, so glad I took the plunge, worth every penny."

The verdict

As a first-hand recipient of the benefits of the K18 Leave-In Molecular Repair mask, I couldn't believe the results after the first use. Presently in "maintenance mode," I've been using this product sparingly when my hair feels like it needs a little extra love and I'm still in awe of the results. Overall my hair feels and looks healthier than ever.

If you're looking to get major results from a single hair product, this mask will not disappoint. While it's an expensive addition to your haircare routine, the minimal amount of product required means the bottle is likely to outlast the rest of your hair products — just make sure to follow the instructions to a T for best results.

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