US Patent 7829181 Solvatochromic visual indicator and the use of the same

A graphic and/or message display system is described. The graphic and/or message display system functions to develop over a period of time a hidden graphic or message on an indicator panel or display area. The hidden graphic or message is revealed when an obscuring graphic reacts with a solvent to change color become at least substantially transparent. The graphic and/or message display system may be used as a stand-alone device or may be incorporated as part of various articles or products, for instance, as a positive reinforcement or a reminder to perform a task. Methods for using the graphic and/or message display system are also described.