Couch marks

1. If draw is too tight as indicated by sound or sight, reduce draw tension.
2. Varying draw (detected by sight or sound) or swings in vacuum can be caused by:
— stock condition.
— flat box or couch vacuums varying.
— wire weaving.
— sealing water not on couch suction box.
— hot bearings or other mechanical trouble.
— if above are normal, then look for mechanical problem.
3. Adjust flow of sealing water on couch suction box to prevent water being thrown out through couch drilling.
4. Reposition shower to provide proper seal without throwing water through drilling of couch suction box.
5. Adjust draw roll to proper position.
6. Heat up sealing water to avoid freezing of couch vacuum box.
7. If the sheet pulls up too high on the roll, the roll holes show vacuum pick marks that may break the sheet.
8. Couch marks can also be caused by excessive sealing water on the couch, resulting from having the shower turned too far upwards.