Felt marking

1. Marking may be due to compacted or dirty press felt.
— the felts must be kept clean and smooth and should not be used beyond their useful life.
2. Good conditioning system set-up will keep weave open and minimize felt marking.
— for the same reason, a herringbone box (20 mm slots, spaced 25 – 40 mm apart, with 15 cm of vacuum on the box) following the nip will help.
3. Check for low vacuum application or a partially plugged area in felt conditioning equipment.
4. Use felt designs of appropriate quality.
— the finer the felt (and, of course, the more expensive) the less felt marking occurs.
— needled felts may eliminate problem because of their construction.
5. Avoid excessive loading of presses.
— use a softer rubber roll if this is possible.
6. A plain smoothing press may minimize felt marking until scheduled maintenance can correct identified problem areas.
7. Ensure that early dryer temperatures are graduated properly.
8. Check high pressure needle showers for excessive water pressure.
— ensure that oscillators are working.
See also Felt cleaning.