Roll barring is very common in the press and calendars sections with rolls that are nipped together. This example is in a Soft Nip Calendar which has two Beltex rolls nipped against a Tripass steel calendar roll. The Tripass roll is of very high-temperature oil running through it in three passes. The Beltex is a softer covered roll and can be barred fairly easily.
Problems caused by Beltex roll
After prolong runs the Beltex will start to bar and only get worse until it causes problems in the paper and then it needs to be removed. After removal, they have to grind the cover to remove the flat spot effects that can be seen if the light hits the roll just right.