Printed indicator compositions

摘要

A method of revealing exposure of a substrate to an environmental stimulus includes exposing the substrate to the environmental stimulus, where the substrate includes at least one indicia, where each of the at least one indicia includes a plurality of chromatically selective scattering particles having a particle size distribution as measured by (weight average diameter)/(number average diameter) of less than or equal to about 1.1, and a colorant; and the at least one indicia exhibits a change in color in response to the environmental stimulus.