I was wracking my brains trying to find a UV bandpass filter, when, quite literally, a light bulb went off in my head. A blacklight bulb that is. Blacklight bulbs are formed from wood's glass
. Wood's glass is a uv & ir bandpass filter.
There are two kinds of blacklight bulb (at least), incandescent and fluorescent. I tested both, good for you, because the fluorescent kind DID NOT WORK. This is good because the incandescent is safer to work with, and cheaper.