Abstract: A method comprising injection molding a plastic part from a polymer formulation comprising an injection moldable thermoplastic and a fluorescent compound, wherein the fluorescent compound has a decomposition temperature that establishes a maximum processing temperature for the polymer formulation. The fluorescent compound will thermally decompose to generate gaseous products causing visible bubble formation in the surface of the plastic part in response to exposure to a processing temperature that exceeds the decomposition temperature of the fluorescent compound. If the plastic part was processed without exposure to a processing temperature that exceeds the decomposition temperature of the fluorescent compound, then any fluorescent compound within the plastic part will cause the plastic part to fluoresce in response to exposure to black light. A suitable fluorescent compound may be, for example, selected from oxalates, carbamic acids, carbonic acids, diazocarbonyl compounds, and combinations thereof.