A team of scientists has developed a novel tattoo ink that can be made temporarily invisible on demand, offering a potential alternative to traditional tattoo removal methods. The innovation, unveiled by Carson Bruns, an associate professor of nanoscience at the University of Colorado Boulder, hinges on a photosensitive pigment that allows tattoos to be "switched off" under certain lighting conditions and reappear when exposed to others.
Bruns demonstrated the technology by tattooing dozens of fish scales along his leg with the new ink, called PhotoTat. The ink contains photochromic chemicals that respond to different wavelengths of light. Under bright torchlight, the tattooed scales turn transparent, effectively hiding the tattoo's appearance, but the design reemerges under ultraviolet (UV) light. This reversible effect is a departure from traditional tattoo pigments, which are permanent in both design and visibility.
According to Bruns, the technology provides a way for individuals to conceal tattoos temporarily, such as during professional situations or social events, without resorting to costly and painful laser removal procedures. “Whenever you decide you don’t want it to be showing any more, you just turn it off,” he said.
Beyond aesthetic applications, the ink could be beneficial in medical contexts. Some patients undergoing treatments like radiation therapy require small tattoos as markers to guide procedures, and an ink capable of toggling visibility could reduce potential social or psychological impacts associated with permanent visible markings.
The current version of PhotoTat offers 16 colour options achieved by mixing primary photochromic pigments; however, the researchers have yet to develop a white pigment. White remains elusive because it reflects light rather than absorbing it, complicating photochromic behaviour. The ink’s permanence applies to the artwork itself, while its visibility can be manipulated, distinguishing it from fully erasable or removable tattoos.
Before PhotoTat can be taken to market, the research team acknowledges that extensive safety evaluations are necessary to ensure the ink’s suitability for human use. The technology is still in the experimental stage, and further studies will be required to assess long-term effects and potential health risks associated with the photochromic chemicals.
The team has published a scientific paper detailing their findings, outlining the ink’s properties and its envisaged applications in the tattoo and medical industries. If successfully commercialised, the technology could offer a new option for tattoo enthusiasts seeking flexibility in displaying their body art.