# PhotoTat: The Science Behind Reversible Invisible Tattoos Researchers develop photochromic tattoo inks that shift visibility under specific light spectrums. - **Source:** [Scientific American Content: Global](https://brifing.si/source/4f066134-e06d-4415-87ef-305e3dc2aba6) - **Published:** 2026-11-01 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/075be77d-0c4a-4336-ab2d-9284b1a18fe7 ## Innovative Photochromic Ink Technology Researchers at the University of Colorado Boulder have engineered PhotoTat, an ink that changes visibility based on light exposure. By utilizing photochromic dyes, the ink transitions between colorless and colored states when exposed to ultraviolet or white light. This development marks a significant shift in how permanent skin markings function today. ## Chemical Mechanism of Color Change The ink relies on light energy to trigger a chemical reaction within the dye molecules. Two to three seconds of UV light forms a new ring structure, turning the pigment visible. Conversely, a blast of white light breaks this ring, reverting the dye to its stable, colorless state for the user. ## Overcoming Historical Stability Challenges Previous iterations of photochromic compounds suffered from instability and degradation after limited cycles. The research team successfully addressed this by encapsulating dyes in poly(methyl methacrylate), a polymer used in medical devices. These stable inks can now withstand over 10,000 activation cycles without losing their ability to switch colors reliably. ## Market Entry and Commercial Availability The biotech company Hyprskn launched a red pigment called Magic Ink in 2024. Currently, a 2ml vial costs 77, making it approximately 100 times more expensive than standard tattoo ink. While compliant with EU Reach safety regulations, the product remains a niche offering due to its specialized formulation and high production costs. ## Current Technical and Safety Limitations The technology faces practical hurdles, including sensitivity to direct sunlight and indoor lighting, which can unintentionally trigger or fade the tattoos. Furthermore, the blue ink variant currently degrades after 10 to 100 activations, leaving a permanent purple mark. Extensive toxicity testing is required before these inks reach general tattoo shops. ## Medical Applications Beyond Fashion Beyond aesthetic use, Carson Bruns envisions significant clinical utility for these reversible tattoos. Patients undergoing radiation therapy or biopsies often require permanent markings that serve as traumatic reminders of their treatment. PhotoTat could allow these essential clinical guides to be rendered invisible once they are no longer needed for medical procedures. ## Future Development and Testing Scope The research team has expanded the palette to include blue, magenta, and yellow, enabling the creation of 16 distinct color combinations. While Carson Bruns has personally tested hundreds of these tattoos on his legs with success, broader public rollout depends on several years of rigorous safety and toxicity evaluations for skin. ## Industry Impact and Community Reception The launch of Magic Ink sparked mixed reactions within the tattoo community, ranging from excitement over creative potential to skepticism regarding its value. As the technology matures, its success will depend on balancing the high cost of specialized dyes with the demand for truly reversible, safe, and long-lasting skin art. ## Sources covering this story - https://www.scientificamerican.com/article/these-tattoos-can-magically-disappear-heres-how-they-work/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._