<prompt> Excessive fixing of an x-ray film:Cause brown stainsReduces the densityIncreases the densityNo effect on density  <response>: The degree of darkening or opacity of an exposed film is referred to as optical density.Excessive fixation causes the image to become light, thereby reducing the optical density of the X-ray film.White and Pharoahs Oral Radiology Principles and Interpretation 8th edition 