The Super Met-Al Pump ActionUltra-Violet White marker utilizes a specially formulated "invisible" ink that fluoresces when placed directly under a black light in combination with standard white paint. Perfect for utilization in high-speed assembly lines, where marks must easily be detectable by both human eyes and machine camera systems. SKM U.V. White markers have also been a major force in the security industry. Where a simple white dot placed on merchandise can be verified for authenticity via the black light fluorescent effect. This marker can write on metal, plastic, glass, and other non-porous surfaces, and is available in both solvent-based or water base formulas. The water based formula is safe on skin!