Impact of non-uniform water absorption on water-interference print mottle in offset printing

Sofia Thorman*, Göran Ström, Patrick A.C. Gane

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

Print mottle is a serious and yet common print defect in offset printing. An imbalance between the feed of fountain solution and the ability of the paper substrate to absorb and transport this water away from the surface can cause moisture/water interference problems. In the study presented here, we have investigated the uniformity of aqueous absorption and coating structure of pilot-coated papers with different types and dosages of dispersants and linked this to print mottle and uncovered areas (UCA). In earlier studies, the print quality of these papers indicated that a moderate addition of excess dispersant caused ink refusal, ink-lift-off (ink-surface adhesion failure) and water-interference mottle when printing at elevated fountain feed. In the present study, we have shown that a majority of the samples with uneven water/moisture absorption and an uneven burn-out reflectance tended to have more severe printing problems related to surface-moisture/water.An aqueous staining technique was used to characterise the absorption non-uniformities. This method has been developed previously with focus on absorption of flexographic water-based inks but can clearly give relevant information also for offset printing, when it comes to moisture/water interference mottle.

Original languageEnglish
Pages (from-to)150-163
Number of pages14
JournalNordic Pulp and Paper Research Journal
Volume33
Issue number1
DOIs
Publication statusPublished - 26 Mar 2018
MoE publication typeA1 Journal article-refereed

Keywords

  • absorption non-uniformity
  • coated paper
  • dispersant
  • offset printing
  • uncovered area
  • water-interference mottle

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