Dyescan 220-6 is a UV fluorescent tracer liquid used in the Peenscan process. Dyescan 220-6 provides a thin film that fluoresces when exposed to ultraviolet (UV) light. The use of Dyescan 220-6 is a superior method for determining the ' of coverage' over conventional colored tracers. Dyescan 220-6 can be used on all types of metals, but is primarily designed for harder substrates, such as steel and titanium, using more aggressive peening processes.