Fluorescent labeling method and substrate

The present invention relates to a method for labeling metal oxides and to a labeled substrate. More particularly, the invention relates to a method for labeling deposits on turbine engine parts to determine effectiveness of cleaning/stripping solutions and procedures. A fluorescent probe is applied to bind to a metal oxide on a substrate and the substrate is exposed to an ultraviolet light to identify the metal oxide. A chemical cleaning or stripping solution is selected by combinatorial high throughput screening (CHTS). In the method, an array of regions is defined on a substrate, a candidate cleaning/stripping solution is deposited onto the regions to effect cleaning/stripping of the regions; a fluorescent probe is applied to bind to a metal oxide on the substrate; the substrate is exposed to an ultraviolet light to identify the metal oxide and a product of the cleaning/stripping is evaluated according to the identified metal oxide. An activated metal substrate composition is provided that comprises a metal substrate with a contaminant metal oxide coating and a fluorescent activator bound to the substrate by reaction with the metal oxide coating.