1. Runnability
• Good runnability is usually connected to
accumulations on blanket vs. washing interval
• There is always something accumulating on blankets
• washing interval can be from 20 000 copies up to hundreds of
thousends copies
• accumulation can be said to affect runnability if
• washing interval is reduced significantly
• print quality detoriates
• risk of blanket damage
2. Accumulation problems
Linting
• Image area problems
• Linting
• typical with uncoated grades
• newsprint, SC
• Fibre picking
• with LWC papers
• connected to shives
Fibre picking
• better screening helps
• coating layer strength
• binder amount
• optimatization between cost of
binder and high enough surface strength
3. Coating picking
Accumulation problems
• Image area problems
• Coating picking
• usually not surface strength problem but connected to
papermaking process
• different precipitations on paper machine or dirt
• does not bind well to paper easily removed in
printing
• Carry-over piling
• printing ink printed in previous unit gets tackier in
following units and starts to pick coating surface
• connected to several factors like Carry-over piling
• ink tack, ink setting speed, water amount on blanket
etc...
• but also to coating strength of the paper
• not much a problem nowadays
4. Dusting
Accumulation problems
• Non-image area problems
• Dusting
• accumulation of pigment particles on non-image
area of the blanket
• uncoated paper with high filler amount
• coated papers with low amount of calandering
(matt, silk)
• accumulation usually purely coating/filler pigment
• Milking
• calcium/fountain solution problems
• transparent white film (calcium precipitate,
for example calcium citrate) on blanket
• not seen very often
• Ghosting / Vanishing dots
• the most current problem in heatset printing!
• main mechanism still unsolved
• a lot of studies in recent years
