Blotches in the sheet

1. Ensure that the lining of approach troughs, pipes, manifold, and headbox are smooth.
2. Ensure that joints fit evenly in headbox area with no projections into the flow.
3. Avoid gaskets.
— if gaskets are used, ensure that they do not protrude into the flow.
4. Minimize air in stock.
— if grade and machine justify it, install air removal equipment.
5. Do not add fillers and retention aids too close together.
6. Avoid one-shot addition of water-insoluble slimicide too close to headbox.
7. Ensure that deflectors are correctly set on forming table.
— if they are improperly set, the succeeding table roll will force water up into sheet.
8. Keep headbox consistency as low as possible.
9. Maintain optimum jet-to-wire speed ratio.
— check TAPPI TIS 0410-05.
10. Deflake broke and use appropriate stock for grade.
11. Check setting of forming board for proper breast roll discharge.
For more information, see Broke spots.