Light-sensitive paper, also known as photosensitive or photosensitive paper, is a distinct material that responds to light exposure. It is an essential component of many photographic processes and has long been a vital tool in the art and science of photography. Light-sensitive paper is made out of a base material that has been covered in a layer of light-sensitive emulsion. This emulsion typically consists of silver halide crystals floating in a gelatinous material. The silver halide crystals, often silver bromide or silver chloride, are sensitive to light and undergo chemical changes when exposed to it. The process starts when the light-sensitive paper is exposed to light via a negative or other light-blocking device. In classic photography, a film negative records the image, and the light-sensitive paper is subsequently exposed to light through this negative during the printing process. The portions of the paper exposed to light undergo a chemical reaction, resulting in the conversion of silver halide crystals to elemental silver. Following exposure, the light-sensitive paper undergoes a succession of chemical treatments. The initial bath often contains a developer solution, which further lowers the exposed silver halide crystals and reveals the latent picture. The paper is then immersed in a stop bath to stop the developing process, followed by a fixer bath to remove any leftover, unexposed silver halide crystals. The intensity and length of light exposure produce a photograph with varied degrees of black, grey, and white. This chemical process is the foundation of traditional darkroom photography, in which trained photographers manage exposure periods, developing procedures, and other factors to obtain desired artistic effects. While digital photography has essentially superseded traditional darkroom techniques in many fields, light-sensitive paper remains an important aspect of several artistic endeavors. Some artists and photographers enjoy the hands-on, tactile aspect of working with light-sensitive paper and traditional darkroom processes, appreciating the craft and the distinct traits it lends to the finished prints.
