Sal ammoniac, or ammonium chloride, is a chemical compound used in certain high-speed photographic developers. It acts to modify the development process, helping to control the activity of the developer and influence image contrast and tonal range.
Sal ammoniac is primarily used in traditional darkroom chemistry for black-and-white photography, particularly when rapid development is needed. Understanding its role helps photographers achieve precise control over image quality, ensuring sharpness, appropriate density, and consistent results during film processing.