It seams like black lights and halloween decorations should just go hand in hand. The black light is the perfect option to make a seemingly “realistic” ghost effect. Making cloth ghosts black light reactive is very simple to do and it only takes a short amount of time. What I have found that works best for cheese cloth ghosts is using RIT Whitener brightener which can be found at most craft stores.
RIT Whitener & Brightener has phosphates that react with the black light also making your laundy whites appear brighter in normal light. To use it all you have to do is mix about a tablespoon of RIT with about 4 cups of water into a spray bottle. The amount doesn’t have to be very accurate I’m just expressing you don’t have to use very much of the RIT dye. I would recommend spray this outside as it will most likely get every where. Just spray and leave it on, no washing required. I touched up an old crank ghost I’ve had for a few years. You can see on the right I just sprayed the RIT dye and on the left I hadn’t spayed. What a difference.