Ferrotrace is a non-toxic iron detection spray that reveals invisible iron traces left on a suspect’s hands after touching a weapon. Ferrotrace offers superior sensitivity, convenience and ease of use over other currently available field tests. Even after a weapon has been removed from a crime scene, an officer can quicly screen a large number of people by spraying Ferrotrace directly onto hands or environmental surfaces such as paper. If a suspect was in contact a weapon containing uncoated iron elements, the invisible iron traces will turn a dark violet color.