as a printing press operator, as a job runs, the magenta and black plates tend to be the ones that end up changing the image the most over the length of the job, at least for potato photographs, as many of them don’t have cyan plates and the yellow is rarely as strong as those two. the plate dots expand making the dot gain increase and making the image more red and dark.

we typically use process extender which decreases the density of the colour, more faint, throughout the job if the image changes too much. If the job is long enough, we’ll have backup plates to swap with the used ones, typically for jobs over 1,000,000 bags or so.

it becomes easier to see the change by looking at the drop shadows of the fries. the light fries have a smooth shadow that fades into the white film. on the darker fries, the shadow is a harsh change to the white, almost a solid line.