A paint or coating composition and method for detecting vapor or liquid reactants, such as ammonia. The composition is composed of ethyl cellulose as a binder, a filler, such as amorphous silica, and a dye, such as bromophenol blue. The composition serves as a passive detector for vapor or liquid reactants when applied to selected surfaces as a paint. The composition is capable of detecting extremely low concentrations of vapor. Further, the composition is capable of regenerating to its original color, thereby providing repeated detection capability.
William A. Mallow;Jerome J. Dzuik, Jr.