Lately, we’ve been spotting a Mertra puffer jacket featuring heat-reactive technology trending on TikTok and Instagram. Outlander Magazine also highlighted it in a recent post, delving into the history of this trend. The post reminded us of iconic Stone Island parkas (arguably the best in this category) and the moment Heliot Emil showcased a jacket literally catching fire during their FW23 runway show. This raises the question: what are the origins of this trend, and why are we so fascinated by it—or not?

What Is Thermochromism, and How Does It Relate to Heat Reactivity?

Thermochromism is the phenomenon where certain materials change color in response to temperature. It’s this effect that makes the color-shifting appeal of heat-reactive clothing possible.

Specifically, a heat-reactive garment is created using a combination of traditional dye and thermochromic dye applied to the fabric. At lower temperatures, the garment retains its original color, but when it reaches about 24°C, the color begins to change, sometimes revealing a pattern.

The Hypercolor T-Shirts of 1991

It was 1991 when Jeans West released a commercial for Hypercolor T-Shirts. A hairdryer, a handprint, or a quick puff of breath was all it took for the shirts to change color instantly. Nostalgia for the adolescent, ultra-’90s vibes of the video made us crave one of those tees ourselves. The playful nature of the product and the effectiveness of the commercial—still surprisingly timeless over 30 years later—played a key role in its popularity. However, a 2022 Vogue article revealed that the brand declared bankruptcy just a year later, in 1992.

The Value of the Trend

In the same Vogue article, Agustina Panzoni commented on the trend: «I think the thermoreactive materials trend is part of a broader movement in fashion driven by TikTok creators: co-creation […] We see it in the popularity of creators designing clothing using everyday items».

As we near the end of 2024—a year marked by significant advancements in textile technology—the return of heat-reactive fashion feels almost inevitable. This cyclical trend continues to captivate, bringing fresh perspectives each time it resurfaces.

The Mertra puffer jacket that inspired this discussion continues to generate buzz on TikTok. Two years later, it’s still resonating, thanks to its positioning closer to gorpcore than the co-creation aesthetic Panzoni referenced in Vogue.

One thing to keep in mind about trends like these is how quickly they vanish, making way for new ones. For now, we’re enjoying the resurgence of heat-reactive fashion, appreciating the technology behind it, and eagerly waiting to see which brands will experiment with this medium next.