What is the effect of over-fixing a film?

Over-fixing a film impacts its overall contrast due to the excessive duration of immersion in the fixer solution. The fixer serves to dissolve unexposed silver halide crystals and stop the development process of the film. If the film is over-fixed, these unexposed crystals are removed too thoroughly, which results in a loss of the density differences that contribute to image contrast.

While over-fixing does not typically lead to the film becoming too clear or excessively dark, it can indeed make the image appear more flat and dull. This is because the vital shades that help distinguish between different tissues or structures within a dental radiograph are lost. The detail may also be diminished as there is less range for the grayscale of the exposures, which is necessary for adequately displaying the features of interest. Therefore, the assertion that over-fixing a film leads to a loss of contrast accurately reflects the resulting quality of the final radiograph.