Figure 4: Fixer stain artefacts. Contact of fixer solution with (i) a radiation-sensitized but not-yet-processed film results irredeemably in a white smooth-edge mark on the radiograph as shown above; (ii) a processed film does not discolor the image; (iii) a non-radiation-sensitized film has the same effect as (ii) but such films should not be used anymore due to the risk of screen stains and developer neutralization during processing. The white patch, as shown above, is evidence of silver halide erosion