The thing to keep in mind when doing blacklight photography is that actual blacklight (UV) is invisible to both the human eye and ordinary photographic films. Therefore UV light simply reflected off an object will not produce an image, either visual or photographic. What we see under UV illumination is from two sources. The first source is fluorescence. UV radiation when absorbed by certain materials causes them to emit light of longer wavelengths than UV, that is to say, in the visible light range. Many dyes and plastics for example fluoresce brightly under UV illumination, emitting visible light of various colors. Many mineral specimens do so as well. Bleached white paper and white cloth usually fluoresce brightly, emitting in the white or near-white range. In the example given above, the white reflective panels are not really bouncing UV light onto the subject. They are absorbing UV light and emitting white light by fluorescence - so the image is actually being taken by white light, not by UV strictly speaking. If you attempted to do this by placing the subject next to a white-painted wall, you would get virtually no light on the subject at all, because white paint does not fluoresce the way white paper does. The second way we see objects illuminated by black light is that the blacklights used for such purposes are longwave UV sources, and as such tend to bleed over into the violet range. Shortwave UV is dangerous. That's the radiation that damages eyes and causes sunburn. A typical UV tube emits both longwave UV and violet light. Therefore non-fluorescent objects illuminated by such a source appear dull violet due to reflected violet light. So, to get a photographic image with UV illumination, without using special UV-sensitive film, you actually have to convert the UV into visible light. If you photographed a model wearing a white T-shirt and jeans, without any supplementary fluorescent sources like white panels, the T-shirt would appear brilliant white, but the model's skin, hair, and jeans would all appear dull purple.
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