Emulsionsskiktet

Emulsionsskiktet, or the emulsion layer, is the light-sensitive coating applied to photographic film, glass plates, or other supports. It typically consists of fine crystals of silver halide suspended in a gelatin or polymer binder, sometimes with color couplers in color films. The layer is applied to a base such as polyester film or glass and may be used on one or both sides of the support.

When exposed to light, photons interact with the silver halide crystals to form a latent image within the emulsion. During development, exposed crystals are chemically reduced to metallic silver, creating a visible image, while unexposed crystals are removed or deactivated by fixing. The emulsion’s response is influenced by crystal size, thickness, and the chemical additives embedded in the layer.

The emulsion layer is often composed of multiple sublayers in modern films, each with different sensitivities to light and spectral responses. This multilayer arrangement allows a broader dynamic range and finer control over contrast and color. Sensitizing dyes, hardening agents, and anti-fogging or anti-halation features may be incorporated to tailor performance, durability, and archival stability. The thickness and grain structure of the emulsion affect image sharpness, graininess, and speed (ISO sensitivity).

Processing plays a central role in bringing the latent image to life. After exposure, the film is developed, the image is fixed, and the emulsion is washed and dried. Although digital imaging has largely supplanted traditional film, the emulsionsskiktet remains a foundational concept in imaging science and archival photography, as well as a point of reference in the study of optical coatings and materials.