The document discusses various print defects that can occur in heatset printing processes. These include optical and surface mottling, smearing, blistering, fluting, cracking, piling, dusting, ghosting, and vanishing dots. It notes that drying problems can result from inadequate or too high drying temperatures. Accumulation on blankets over many print runs can affect runnability and quality if the washing interval is reduced significantly. Specific accumulation problems mentioned are coating picking, carry-over piling, dusting, linting, ghosting, and vanishing dots.

1. Print defects in heatset Paper related print through optical mottling Paper surface related backtrap mottling, water mottling scuffing (rub-off) picking, hickeys Drying related smearing, blistering fluting, cockling fibre roughening, cracking Accumulation related carry-over piling, dusting ghosting, vanishing dots

2. Scuffing with matt/silk grades Printed signature goes through many operations that involve pressure and movement at the same time

3. Too low drying Inadequate drying Too high drying Blistering Fibre roughening Cracking Fluting Drying problems

4. 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 thousands copies Accumulation can be said to affect runnability if washing interval is reduced significantly print quality detoriates risk of blanket damage

5. Accumulation problems Coating picking (Hickeys) usually not surface strength problem but connected to papermaking process Carry-over piling printing ink printed in previous unit gets tackier in following units and starts to pick coating surface Dusting / Linting accumulation of pigment / fibre particles on non-image area of the blanket Ghosting / Vanishing dots the most current problem in heatset printing! main mechanism still unsolved a lot of studies in recent years Coating picking Carry-over piling Dusting Hickeys

6. Vanishing dots and ghosting ghosting vanishing dots