Cool How To Make A Black Light Filter Ideas. Cut a piece of cling wrap the right size to fit over the lens with some wrap remaining to go down the side of the flashlight. Black lights are designed to filter out most of the visible light emitted by the lamp, leaving only the uv light.

The more transparent, the better and more vivid result. Rubber bands one blue sharpie one purple sharpie one torch (or flashlight for the americans) some glad wrap/cling wrap/saran wrap/clear stuff! Web make sure that the black light filter is installed correctly.