K18 Biomimetic Hairscience

HeatBounce™ Leave-In Conditioner Heat Protectant

4.5 · 555 reviews
5,098 ₽

What it is: A leave-in conditioner with resilicore technology that detangles, softens, and intensely protects hair up to 450 degrees Fahrenheit.Hair Texture: Straight, Wavy, Curly, and CoilyHair Type: Fine, Medium, and ThickHair Concerns:- Dryness- Heat Protection- ShineKey Benefits: - Protects from heat up to 450 degrees Fahrenheit- 85 percent less breakage after blow-drying- Lightweight formula conditions, softens, and detangles even damaged hairHighlighted Ingredients:- Resilicore Heat-Shielding Technology: Patented tech for heat protection from cuticle to cortex—more intense than ever.What Else You Need to Know: Resilicore heat-shielding technology is a breakthrough innovation inspired by resilin—a natural protein that can withstand extreme temperatures. Unlike traditional heat protectants that only coat the cuticle, the size and molecular makeup of Resilicore allows it to penetrate deeper than ever before, into the cortex where heat damage can occur, forming a protective shield that fortifies from within. Created for all hair types and textures. Can be used on extensions.Clinical Results: In scientific testing with application of K18 HeatBounce and use of 450℉ (232℃) flat iron on dry hair:- Reduction in hair breakage - Heat protection up to 450℉/232℃ from the cuticle to cortexIn scientific testing after application HeatBounce on damp hair and exposure to 450℉ (232℃) flat iron on dry hair - Increase in protein stability- Heat protection up to 450℉/232℃ from the cuticle to cortexIn scientific testing after application of high-heat blow-dry:- Reduction in hair breakage- 85% less breakageClean at SephoraClean at Sephora is our commitment to offering formulas that go beyond regulatory standards to avoid controversial ingredients without sacrificing effectiveness.

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What it is: A leave-in conditioner with resilicore technology that detangles, softens, and intensely protects hair up to 450 degrees Fahrenheit.Hair Texture: Straight, Wavy, Curly, and CoilyHair Type: Fine, Medium, and ThickHair Concerns:- Dryness- Heat Protection- ShineKey Benefits: - Protects from heat up to 450 degrees Fahrenheit- 85 percent less breakage after blow-drying- Lightweight formula conditions, softens, and detangles even damaged hairHighlighted Ingredients:- Resilicore Heat-Shielding Technology: Patented tech for heat protection from cuticle to cortex—more intense than ever.What Else You Need to Know: Resilicore heat-shielding technology is a breakthrough innovation inspired by resilin—a natural protein that can withstand extreme temperatures. Unlike traditional heat protectants that only coat the cuticle, the size and molecular makeup of Resilicore allows it to penetrate deeper than ever before, into the cortex where heat damage can occur, forming a protective shield that fortifies from within. Created for all hair types and textures. Can be used on extensions.Clinical Results: In scientific testing with application of K18 HeatBounce and use of 450℉ (232℃) flat iron on dry hair:- Reduction in hair breakage - Heat protection up to 450℉/232℃ from the cuticle to cortexIn scientific testing after application HeatBounce on damp hair and exposure to 450℉ (232℃) flat iron on dry hair - Increase in protein stability- Heat protection up to 450℉/232℃ from the cuticle to cortexIn scientific testing after application of high-heat blow-dry:- Reduction in hair breakage- 85% less breakageClean at SephoraClean at Sephora is our commitment to offering formulas that go beyond regulatory standards to avoid controversial ingredients without sacrificing effectiveness.

Customer reviews

5.0
verified purchase
Amazing

I love this! I have fine thin hair and it makes my hair so soft. And the heat protection is a bonus!!

9/12/2026
2.0
verified purchase
Eh

For reference-I have a lot of hair but it’s fine. I sprayed the product on and then blow dried. I am not impressed with how it has made my hair feel. It’s made it feel a little heavy, dry, and “waxy”. Seems like it should be a great product. Not sure if I will keep it. As I may sacrifice the feeling of my hair for true heat protection.

9/9/2026
5.0
verified purchase
Less is more, leaves hair feeling so good

Absolutely love this stuff. The first time I sprayed it on a section of hair, I sprayed a generous amount and felt a weird film afterwards. I was more conservative with my sprays the second time styling and it felt so hydrating and lightweight. Less is definitely more when it comes to applying this product

9/2/2026
2.0
verified purchase
Does the job, but…

Smells good, does protect the hair, but not without leaving a heavy weighted feeling. Glad it was a mini.

8/9/2026
5.0
verified purchase
HOLY GRAIL ✨✨✨

Best heat protectant i tried! I can’t explain how my hair it feel when i use this.

7/21/2026
5.0
verified purchase

I've used this product for about a week, safe to say it's my favorite heat protector! My hair not only was protected but it smells amazing and is bouncy and weightless. Also there's som significant hold to my hair.

7/6/2026
5.0
verified purchase

My fine hair loves this. I notice significant difference in frizz too

7/1/2026
5.0
verified purchase
Love it love it!!

I bought the small bottle to try it out and oh my goodness this stuff is good. My hair is so smooth and shiny and blows out very nicely. My hair has good traction on the brush still. Great product and I will definitely buy this again in the bigger size.

6/23/2026
3.0
verified purchase
A little heavy for fine hair

This was a little heavy for my fine hair and didn’t do anything amazing for me. It smells nice, but I think there are better heat protectants on the market.

6/16/2026
3.0
verified purchase
Sticky :(

I really wanted to like this product because I LOVE K18, but it’s extremely plastic-y and synthetic feeling, which makes it impossible to distribute evenly through hair. Maybe it just isn’t meant for me…

6/16/2026