Piling is an unwanted effect, where the pigments of the ink build-up negatively on the blankets. Serious print-quality-issues, as well as early blanked wear, follow.
Suspect 1 – Ink/Fountain-additive incompatible
In most cases, the fountain additive is not working well with the ink in use. Chemical interactions between the printing plate and the fountain additives make the plate accept lesser water. Micro-Toning effects make pigments separate from the ink’s binder and build upon the blankets around image-areas.
- Check the fountain solution
- Find proper additives for inkset
- Adjust additive concentration accordingly to manufacturers recommendation
- Check and optimize blanket cylinder packing
- Try a different set of ink
Suspect 2 – excessive cylinder pressure
Excessive pressure may separate inks binder and pigment. This is only true for low quality inksets.
- Reduce pressure between the plate cylinder and blanket cylinder
- Use higher quality inkset
Suspect 3 – Ink over-emulsified
Especially UV-curing inks are sensitive to over-emulsification. Too much water merged with the ink may alter the inks probabilities to transfer correctly.
- Reduce dampening level
- Mechanically adjust dampening system
- Clean dampening system
- Decalcify rollers of the ink train
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