OG fans of K18 know that our beloved leave-in molecular hair mask is worth the hype. Praised by beauty editors, industry pros, and reddit sleuths alike, and with over 20+ billion views on TikTok, it’s a holy grail product that delivers heaps of clinically proven benefits—and it works in just 4 minutes.

It’s simple to use and easy to love, but questions still arise on best mask usage throughout our community. So here, without further ado, please find the answers to your most-asked mask questions.

How often should I use it?

Our mask is designed to be a powerful treatment that repairs damaged hair. But the key to using it effectively is understanding how often to apply it and how much to use.

Generally, you can use it once or twice a week, depending on how much repair your hair needs. If your hair is very damaged or over-processed, you might want to start using it more frequently, but if you’re maintaining healthy hair, once a week should be plenty.

How much should I use?
For most people, a little bit will go a long way, and using too much can actually weigh hair down or leave it feeling greasy. So, it’s important to use just the right amount. Use our calculator to find your ideal dosage.

Does it work for all hair types?
Yes. Whether you have straight, wavy, curly, coily, fine, thick, or aging hair, the mask has the ability to help repair and strengthen your strands.

I have curly and coily hair. Should I use it?

Yes! The mask works beautifully for this hair type because it helps to detangle and define curls while also providing essential repair. After applying the mask, detangle with a wide-tooth comb or your fingers to help enhance the shape and definition of your curls as you let them air dry or diffuse them (the mask’s treatment properties will also protect curls from heat damage during the styling process).

I have aging hair. Is this product for me?

Yes! Aging hair is often more fragile and prone to breakage, and the mask can make a significant difference in preserving your hair’s natural integrity. One key tip: when applying the mask, focus on the areas that need the most care first. With aging hair, this is usually around the temples, crown, or nape of the neck. This can help you achieve an even, nourished result without overloading your hair with product.

My hair is really damaged. How should I mask?

The mask is especially effective on damaged hair, whether caused by heat styling, chemical treatments, or environmental factors. To apply: Focus on the most compromised sections first—such as the mid-lengths and ends—before working the product toward healthier areas, using a gentle touch. This will ensure that your hair gets the concentrated treatment it needs without over-saturating healthier sections.

Should I skip conditioner after?

This is our most-asked question of all time, and the short answer is: yes, you can skip conditioner after! The mask itself is highly conditioning and also works as a light detangler, so simply apply and let it work its magic. If you have particularly dry hair, though, you might choose to follow the mask with a light leave-in conditioner or styling product, but it’s generally not necessary.