What's an Emulsion?
Basically, photographic emulsion is a colloidal suspension of liquid within another liquid. In other words, photographic emulsion is more of a gel-like substance rather than a substance that's totally liquid. It typically contains silver halide crystals, which disperses evenly throughout the gel.
The silver halide crystals, which are light-sensitive, rest in the gelatinous material; they can be incorporated onto a variety of mediums such as paper, plastic, fabric, or glass during the manufacturing process. In photographs, the silver halide reacts to the chemicals used in the film developing stage, which produces the image from the film on the photograph paper. It's a slightly different process when it comes to promotional products.