pH is a scale used to measure the acidity or alkalinity of a solution, ranging from 0 to 14. It is determined by the concentration of hydrogen ions present, with lower values indicating acidic solutions and higher values indicating alkaline solutions.
In photography, understanding pH is important for preparing chemical solutions, such as developers, fixers, and toners, to ensure consistent results and protect both film and paper. Distilled water is neutral with a pH of 7, while careful adjustment of pH levels in photographic chemistry can influence image quality, contrast, and archival permanence.