This highly fluorescent Invisible Skin Marking Ink can be swabbed, dabbed or stamped on the skin. It dries immediately with no visible trace and fluoresces a brilliant blue/white when exposed to longwave (UV) radiation. Use fluorescent invisible skin marking ink with an ultraviolet light to control access or egress at facilities such as prisons, detention houses and other control areas. Identifying dates, times and other symbols are easily changed with a combination of stamps and stamp pads. Available in 16 oz. (473ml) or 32 oz. (946ml) volume.