UV-induced Fluorescence Photography

Ultraviolet-induced fluorescence photography is an imaging technique that records visible light emitted from certain materials in the form of fluorescence when these materials are exposed to UV radiation. Essentially, fluorescence is the phenomenon observed when certain materials absorb UV light and emit it back as lower energy radiation (longer wavelengths). In this case, this lower energy radiation corresponds to the visible part of the EM spectrum. It may also correspond to different intensities and colours based on the fluorescing material(s) observed.

This technique is extremely beneficial in the case of aged varnishes which according to their origin (natural or synthetic) as well as their degree of ageing, exhibit diverse fluorescence intensities and colours. For example, aged dammar and mastic varnishes exhibit a strong, slightly opaque and green fluorescence. It must however be noted that despite its usefulness as a diagnostic tool, UVF photography is merely indicative as to the nature of the materials that fluoresce and must not be used for reaching definite conclusions.

UV fluorescence photography procedure

1. Position your object on the easel.
2. Set up your tripod and the Canon EOS 6D camera as usual.
3. Adjust the height of the easel and properly frame your shot.
4. Remember to correct the white balance of the camera accordingly. To adjust the white balance, press the “Q” button on the back of the camera and use the wheel to navigate to the white balance settings. To confirm your settings, press the “Set” button twice.
5. Place the Kodak Wratten 2E filter onto the lens of the camera (make sure it screws in place and secures). The Kodak Wratten 2E filter cuts off all wavelengths of light below approximately 410 nm.
6. Position the UV lamps at the 30°-45° angle mark.
7. Put a sign for UVF photography outside the studio door. This will alert others that UV radiation sources operate inside the room.
8. Before plugging in the lamps, wear a pair of UV goggles!
9. Plug in the lamps. Ensure that the cables do not pose trip hazards (you wouldn't want that in a darkened room)!
10. Switch on the room’s safelight (if any).
11. Adjust the lamps’ position and/or angles accordingly. You might find out that your object reflects UV light to a degree that is not desirable. If this is the case move the lights in such an angle and/or distance that the unwanted reflections disappear.
12. Proceed with photographing your object.
13. When finished, unplug the lights sources first, then switch off the safelight and take off your goggles.
14. Remove the warning sign.
15. Wrap all the cables.