I have been experimenting with different backgrounds for UV-imaging, but have found most to not be very suitable for various reasons. There are certain characteristics which are important to consider when choosing your background for UV-imaging.
1) It needs to be matt and not over reflective, as this could result in ‘hotspots’ in the background.
2) It needs to be dark enough that it will not have blown highlights at maximum power of the light source used.
3) It should be unobtrusive and not distract from the subject being photographed in the light being used to photograph the subject.
4) It should ideally work in all the different light spectra being used (visible, UV, Insect-D-sight).
5) Ideally it should be black/grey in colour in the various lighting used.
My current background fulfils nearly all of the above criteria, although it can have a slight tint in Insect-D-sight. I use Westfoam black foam-board in A3 size, although it is also available up to A1 for much larger subjects (but the A3 foam-board fits perfectly in my home studio setup). It costs about £3.55 per sheet, although I bought a pack of 5 (the A1 sheet costs £7.99).
This is what the background looks like at the typical lighting level used for UV-imaging of flowers.
This is what it looks like when I use full power from the Quantum X2D, e.g. when imaging very UV-dark subjects like the purple Aster. With grey or white backgrounds, at this level of lighting there will be white or overblown highlights in the background. This foam-board just about gets away with it.
It also works well in Insect-D-Sight. In fact it could be used for white balance setting as well. As it is always in the background, it can serve as the white balance reference standard; as long as the same reference is used, it will allow for comparison of different subjects against each other. In fact I have found that it does allow custom white balance which gets very close to that obtained from using sintered PTFE.