If you are in a cave i’m assuming you’ll be doing archeological photography. If this is just some art that looks good under black lights, ignore this advice.
There are specific things that need to be done for this to work correctly. First, don’t wear light colors, anyone in the room should be in dark, preferably black clothing. Don’t forget your shoes.
Second, contra previous posters, you want a filter that actually blocks most visible light, and only allows in UV light and some fluorescence (sp?) light.
Kodak Wratten 2A, 2B, 2E and Baader UV/IR Cut filters work for this. You can buy from other companies, they may or may not use the same filter codes. These allow for some violet light to pass through.
If you can hang black felt behind your subject even better.
Specialty cameras are often used for this type of photography. See this Fuji camera.
You need a slightly more specialized UV light source to pull this off well. Most UV lights will admit a lot of visible light as well. You want to restrict the light to just uv and trace amounts of violet. Exitation Filters will do the job, but they aren’t cheap.
Some cameras do not perform well for UV photography due to filters over the sensors or from the glass in the camera lens absorbing some of the UV light. Can’t comment as to how yours will perform
Here is an article that describes shooting paintings with UV light as well as other photographic techniques.
This is not a cheap or easy task.