When exposed to heat, what effect does it have on film sensitivity?

When film is exposed to heat, it can cause the film to fog. Fogging refers to the unwanted exposure of the film, which can occur due to thermal energy that affects the emulsion layers where the photosensitive materials reside. This undesired exposure reduces the clarity and contrast of the image produced on the film.

Increased temperatures can lead to random excitation of the silver halide crystals in the emulsion, causing them to react as if they had been exposed to light. This results in a condition where background densities rise, making it difficult to distinguish between the intended image and the fogged areas. Thus, while some factors like higher levels of radiation can typically increase sensitivity, heat directly results in fogging, significantly degrading the quality of the film.