Tattoo that can vanish without being removed: Chemists develop multicolor ink that fades in sunlight and reappears with UV light in seconds

A team of chemists has developed a cool tattoo ink that switches on and off with different kinds of light, meaning that although it’s permanent, you could hide it anytime. It can be doodled on one's own skin within seconds using a simple laser pointer, which will also be “nearly invisible at rest.”

Led by Carson J. Bruns, the study was published in the Cell Press journal Matter & Light on October 9, 2026. “Tattooing is a very ancient technology that remains mostly untapped as a platform for today's technologies,” the lead author and an associate professor of biomedical engineering at the University of Colorado Boulder said in a news release.

“This is a tattoo that you can have, and whenever you decide you don't want it to be showing anymore, or you just don't want it there, you just turn it off,” he explains to Livescience.com. “And that's it. You don't have to turn it on again.”


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How does the new PhotoTat ink work?

Commercially known as PhotoTat, the researchers made the inks from dyes and a Plexiglas-like material generally found in many medical technologies on the market today, including dermal fillers.

In PhotoTat, three primary colors, blue, magenta, and yellow, are made with photochromic dyes, which can change color depending on different wavelengths.

Light-responsive dyes alter their molecular structure when exposed to specific wavelengths of light. According to Bruns, a 365-nanometer ultraviolet (UV) LED activates these pigments in just two to three seconds. Once triggered, the colors will be visible for hours or even days under normal lighting. However, when the wearer steps into the bright outdoor sun, the intense light completely erases the colors within seconds.

So, in the case of PhotoTat, like normal tattooing, the pigment remains in the skin, but the tattoo’s appearance changes, depending on the intensity of lighting.


“PhotoTat is like a switch. You turn it on with UV light, but you can turn it off again when you go to grandma's house,” Bruns says.

The team also found that all three PhotoTat channels can be switched under the skin for between 1.4 and 2.2 years.

New tattoo ink could have medical applications

This new multicolor tattoo ink could also have more serious applications, like for medical tattoos that need to be visible when a doctor wants to see them, the researcher reported. “With PhotoTat, we could turn an involuntary medical tattoo into something that's only visible to the doctor when you go into the clinic, and then it can be invisible the rest of the time.”

“You won’t find PhotoTat at any tattoo parlors yet,” the news release said, but Bruns and his colleagues are hoping to continue improving their designs in the future.

Researcher tests the ink on himself but safety reamins unconfirmed

Bruns, who has tried the new tattoo ink on himself, has yet to determine whether the inks are safe for others. With this new ink, he has made a black outline of fish scales on his leg. With a little light, he can turn those scales red, orange, blue, and more; almost like “magical mermaid scales,” he concludes.