I would have to turn off all the lights and board up my windows to make this weak little black light thing work on the pictures it comes with.
You don't have to make the room dark to demonstrate the differences of UV blocking using the Tru Vue display. A few suggestions:
1. Put the display in a small box or under a shelf to cast a shadow on the three images. The box the display came in would work for this purpose if you care to tape the flaps open and cover it with decorative paper.
2. Like all fluorescent lights, this one takes a few minutes to develop full brightness. Turn it on first, then explain what you are about to demonstrate before you actually do it.
3. If you hold the light directly against the glass, you can see slight UV illumination on the left two images even in normal room light. The difference is not very dramatic, but it is discernible.
4. As others have suggested, you can get a better UV light for a small price, if you find the demonstration to be useful with customers.
Tru Vue's main goal probably was to demonstrate the difference to framers, but it makes sense to share the information with customers. Tru Vue has always been good about providing point-of-sale demos, but the cost of designing, assembling, and shipping thousands of those UV-lights and frames has to be huge. Has any other supplier made that sort of commitment to helping framers?
Still using Tru Vue in my frame shop every day and consulting for the company.