Freeness varying

1. Most stock freeness changes are transient, and changes made should be as few as possible.
2. A system of measuring and recording total flow from flat boxes gives a positive indication of the size of the freeness change and permits adjustments to be made with more confidence.
3. Check the stock supply system.
— it is often assumed that the chemical pulp furnish is uniform which may not be true.
4. Check with the groundwood mill for groundwood containing papers.
(a) is the mill discipline, stone sharpening spacing, maintenance load control, etc. adequate?
(b) is storage and blending adequate?
— confusion often exists between storage which may be adequate and blending which is quite separate and is frequently inadequate.
(c) are changes due to changes in wood supply that could have been foreseen and allowed for?
5. If stock is too free:
— reduce flatbox vacuum.
— increase refining at machine Jordan.
— put on water to maintain formation.
— raise slice to maintain head.
— reduce or eliminate steam from wire pit or silo.
— reduce vacuum on wet suction boxes.
— reduce foil angles.
— drop table rolls or foils.
— increase percentage of broke.
— increase defoamer usage.
— increase shake.
6. If stock is too slow or wet:
— increase flatbox vacuum.
— decrease refining at machine Jordan.
— take out water to avoid crushing at dandy or having too wet a sheet off couch.
— drop slice to maintain head.
— add steam to system, e.g., to wire pit or silo.
— increase vacuum on wet suction boxes.
— increase foil angle but may get excessive disturbance.
— put up drainage elements.
— decrease percentage of broke.
— decrease defoamer usage.
— decrease shake.