Several times over the years I have heard of tension variations resulting in damaged coatings. I referred to Roll and Web Defect Terminology, 2nd Edition, by R. Duane Smith. The coating defect that may be caused by tension variations is Blade Wrinkle.
One very serious consequence of tension variation is Web Wander. The web wandering may put the edge of the web at the point where the coating stops and an old blade becomes notched. This can cause web breaks.
I have also seen cases where a glass-like coating can be cracked if the tension becomes a bit too high. In this case the normal running tension was extremely low. Very accurate tension measurement is required to control tension to this precision.
I do not have much experience in the field with damaged coatings and would welcome comments or a Technical Topics entry here by readers.