What happens when artworks are illuminated with ultraviolet light?

Some materials absorb invisible UV radiation and re-emit it as visible light, producing the fascinating phenomenon known as Ultraviolet Fluorescence (UVF). The colors and intensity of this glow depend on the chemical composition and age of the materials.

In art examination, this simple but powerful technique can reveal varnishes, retouchings, restorations, and material differences that are completely invisible under normal lighting. Because it is non-invasive and relatively easy to perform, UV fluorescence photography has become one of the most useful tools in technical photography for the study and documentation of artworks.

In this page I introduce the basics of UV Fluorescence Photography (UVF) and how it can help conservators, scientists, and art professionals better understand the history and condition of artworks.

UVF is a phenomenon in which certain materials absorb invisible ultraviolet radiation and re-emit part of that energy as visible light. When illuminated with UV lamps, many natural and synthetic substances glow with characteristic colors—blues, greens, yellows, or reds—depending on their chemical composition. In artworks, this response can reveal information that is invisible under normal lighting.

In art examination, UV fluorescence is widely used as a fast, non-invasive diagnostic tool. Natural varnishes, resins, retouchings, adhesives, and some pigments fluoresce differently, allowing conservators and researchers to distinguish original materials from later additions. Areas of restoration often appear darker because modern retouching paints typically absorb UV radiation rather than fluoresce. Aged varnishes, on the other hand, commonly produce a greenish fluorescence that helps visualize their distribution and thickness.

Check out other applications of UV fluorescence beyond art examination in our series “Fabrizio vs the Fluorescent World.”