Summary As a measure of acidity or basicity of an aqueous solution, pH is an excellent tool. When used in combination with titration, it is a simple means to monitor bath concentration and/or soil loading potential. Used with non-aqueous solvents, pH is much less reliable and should be used in reference to a similar fluid only. pH is one of several methods used to help classify substances as corrosive, hazardous, or environmentally friendly and people-safe. Guidelines are established regarding first-aid treatment, handling methods, and storage practices related to water-based or water-soluble solutions. Other test methods, like flash point, are preferred for use with non-aqueous or water-insoluble solutions when establishing application, storage, and handling practices.