Chemists create disappearing tattoos: Here's the science behind how they work

Here, PhotoTat is combined with conventional tattoo ink to add elements that colorize when exposed to UV light and decolorize under white light. Credit: Matter & Light, Bruns et al., CC BY-SA

How handy would it be if you could make your tattoos invisible for a job interview in the morning, and reveal them again for a party in the evening? This sounds like science fiction, but it may soon be reality.

Researchers at the University of Colorado Boulder have developed invisible tattoo ink that can be revealed with a UV flashlight and stays visible until switched off with white light. They have published their research in the journal Matter & Light.

They created different motifs with this ink ranging from a lantern that reveals its light when activated, to multicolored scales like those in the much-loved children's book "The Rainbow Fish."

The pigments used in these inks are so-called photochromic dyes (from the Greek "photos," which means "light," and "chroma," which means "color"). In other words, they are compounds that change color when exposed to light. These dyes have been used for years in color-changing sunglasses.

Light carries energy, and photochromic compounds are designed in such a way that this energy is enough to cause a chemical change that alters the shape and therefore the properties of the molecule.

Two or three seconds of bright UV light is enough to form a new ring in the dye molecule, switching a colorless pigment to a colored one. Credit: Miriam O'Duill

In the case of the "invisible" tattoo ink, two or three seconds of bright ultraviolet (UV) light is enough to form a new ring in the dye molecule, which switches a colorless pigment to a colored one. A variety of colors are available depending on the exact structure of the molecule.

A blast of bright white light reverses the reaction, breaking the ring and turning the color off again. For a long time, the challenge with this chemistry was that the colored form of the dye was relatively unstable and quickly reverted to the more stable, colorless form—especially at higher temperatures.

Another issue was fatigue: after a certain number of on-off cycles, the dyes degraded and took on a permanent colored hue. Have you ever bought transition lens sunglasses and noticed that they became less effective over time? This is due to the same deterioration of photochromic compounds in the lenses. But thanks to recent research efforts, remarkably stable dyes have been designed that reliably hold their color for months and can undergo over 10,000 activation and deactivation cycles without degrading.

Carson Bruns' team at the University of Colorado Boulder showed that these pigments could be formulated into tattoo inks by encapsulating them in poly(methyl methacrylate) (PMMA), a polymer approved for medical use in bone cement, dentures and intraocular lenses. This family of inks is known as PhotoTat.

Time to market

So, when will you be able to get one of these switchable tattoos? A red pigment was already launched in 2024 under the name Magic Ink by Colorado-based biotech company Hyprskn. A 2-milliliter (ml) vial will set you back £77, which is about 100 times more expensive than regular tattoo ink due to the specialized dyes and formulation process required. The ink is fully compliant with the EU's Reach (Registration, Evaluation, Authorisation and Restriction of Chemicals) safety regulations.

Now, Bruns' research team has developed three more PhotoTat inks—blue, magenta and yellow—that can combine into 16 other colors. "So far," Bruns says, "the only person who's tested this ink is me. I actually have hundreds of these tattoos on my legs now and they've all gone really well."

Some challenges remain, though: direct sunlight contains enough UV radiation to activate the tattoos unless they are protected by sunscreen. Indoor light will slowly switch them off over a period of several days.

In addition, the blue ink currently degrades after only 10–100 activations, leaving a permanent, purple-colored mark. Most importantly, the inks need to undergo thorough toxicity and safety testing before they can be rolled out to tattoo shops for general use, which will likely take several years. Don't get your hopes up just yet about your new "business during the day, party at night" look.

When Hyprskn launched Magic Ink, the reception in the tattoo community was mixed. While some tattoo enthusiasts viewed it as a revolutionary creative tool, others thought it was an overpriced gimmick. Bruns does not only see his photochromic tattoo inks as fashion accessories, however.

He also envisions medical applications, for example, for patients who need permanent skin markings to guide radiation therapy or identify sites for biopsies. Bruns argues that these markings "become a permanent reminder of a traumatic experience," which can be mitigated by making the tattoo invisible once it is no longer needed in a clinical setting.

Who's behind this story?

Gaby Clark

MA in English, copy editor since 2021 with experience in higher education and health content. Dedicated to trustworthy science news. Full profile →

Andrew Zinin

Master's in physics with research experience. Long-time science news enthusiast. Plays key role in Science X's editorial success. Full profile →

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Citation: Chemists create disappearing tattoos: Here's the science behind how they work (2026, October 30) retrieved 30 October 2026 from https://phys.org/news/2026-10-chemists-tattoos-science.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.