Sensitive Independently Published Sensitive Paper: Droplet Measurement Using

Sensitive (color reactive) paper can be used to detect (and measure) droplet impingement. Use of sensitive paper for drift measurement (water droplet carryover from evaporative cooling systems) was developed by J. D. Womack in the 1970s. Initially, the method was very labor intensive, requiring many hours examining the papers with a microscope. In more recent years, scanning, digitizing, and even pattern recognition utilizing AI has made the process much more accessible and cost-effective so that it has become more widely used. In this text we will discuss the concept, history, processes, techniques, challenges, and applications.