Refining and paper problems

1. When ash test is low, improve filler retention by closing up the sheet with more refining.
2. Blowing on the Yankee is probably due to inadequate adhesion that can be helped by increased refining.
3. Sticking to the Yankee reflects a structure that is too tight and probably has too many fines.
— both conditions are improved with reduced refining.
4. Blow marks usually occur when the stock is too slow.
— back off some refining if other tests permit.
5. Broke spots are usually the result of insufficient defibering in repulpers.
— improve deflaker action.
— may need to increase tickler refining.
— it is unlikely that refiners will produce their intended effect if they are expected to perform also as deflakers.
6. If bulk is too low, reduce refining to help open up the structure.
7. Burst or Mullen usually change directly with refining.
— adjust refining as needed for tests.
8. Calender blackening and mottle are caused by poor formation.
— refining may help to level the sheet on the forming table.
9. Caliper changes inversely with refining.
— adjust refining if other tests permit.
— initial refining produces greatest caliper decrease.
10. Cockles develop upon drying and reflect the mass distribution of the web.
— it usually helps to cut back on refining and improve formation.
11. Dandy crushing occurs when too much water is carried under the dandy roll.
— reduce refining to free up the stock.
— increasing stock temperatures often helps.
12. Curl problems are often reduced by increasing the short fiber content of the furnish or by cutting back on the amount of refining.
13. Porosity (air permeability) responds rapidly to changes in refining.
— can increase air resistance by increasing the amount of refining or the refining consistency.
14. Feathering is usually due to inadequate or fugitive sizing but may be aggravated by stock that is too free.
15. A poor MG finish can come from poor formation or poor adhesion to the Yankee surface.
— increased refining can help both formation and Yankee adhesion.
16. Formation problems arise from poor drainage on the wire and are aggravated by too much long fiber in the furnish.
— increased refining may help formation but one will usually need to reduce the percentage of long fiber.
17. Lint and fuzz result from poor bonding of fibers and/or excessive short fiber (fines).
— increased refining will improve bonding but may need to reduce any cutting action of the refiners (Jordans) and free up stock a little.
18. Grainy edges are mainly due to non-uniform fiber distribution on the forming table.
— less refining can help to reduce non-uniform shrinkage at the edges.
19. Picking on the wire is usually due to slow stock.
— this is corrected by less refining.
20. Internal bond varies directly with refining but may also need to improve the formation.
21. Pickouts at the press can be due to excessively free stock or excessively slow stock.
— adjust refining to get conditions needed.
22. Short fiber or excessively slow stock aggravates shadow or shell marking at suction couch or suction press rolls.
— check refining to see if a reduction is needed.
23. Softness in tissue products is adversely impacted by virtually any amount of refining.
— by-pass refiners or keep refining at the lowest level possible.
24. Stiffness is influenced by both refining and furnish composition.
— tensile stiffness is improved with refining but must be careful not to take too great a caliper loss.
— brittleness (rattle) is related to the short fiber content so need to avoid fiber cutting in refining.
25. Stretch generally increases with increasing refining or refining consistency.
26. Tear responds inversely to the amount of refining the stock receives and directly with the long fiber content.
— may need to reduce refining but definitely must avoid cutting in the refiners.
27. Tensile strength varies directly with refining and usually improves with both increased fibrillation refining and increased refining consistency.
28. Absorbency rate and capacity are both influenced by refining.
— closing the sheet structure can improve absorbency rate but may reduce the capacity.
29. Watermarking usually improves with well-formed and closed sheet structures.
— increased refining usually leads to improved impressions.
30. Wire marks are more prominent with low freeness stock.
— adjust refining as needed.
— also need to check position of dandy roll.
31. Wood slivers in the sheet usually arise from contaminants entering the system but occasionally come from wood spacers used in conical refiners.
— examine the condition of the conical refiners.
32. Wrinkles appearing at the wet end or press section are a result of stock that is too slow.
— reduce refining to extent permitted by tests.