Using ISIT as a Probe to establish Critical Roughness – film thickness relationship

Mika Anttila, Martti Toivakka, Patrick Gane

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


In the offset process, ink film splitting and release properties impact strongly on the stability of the paper surface. The determination of the pick velocity and the pick resistance is one of the most widely used surface strength tests for coated offset papers. Generally, the tack properties of a test ink or viscosity of a test oil
are considered to be the control parameters for generating the separation force required to evaluate surface strength. A frequently overlooked parameter, however, is the influence of the release properties of the materials forming the print nip, i.e. print roller (blanket) and the coated paper surface. In this work, we set out to establish the relationship between paper surface roughness and the critical liquid film thickness (CFT) which determines the force level generated in respect to adhesion and surface contact area. The CFT is here defined as
the film thickness distribution on the surface at which the maximum tack force (release force) value is achieved. A series of six specially designed highly latex bound ground calcium carbonate (GCC) coated papers having
different roughness were tested using the Ink Surface Interaction Tester, ISIT, in respect to measured release force using the extensional tack measurement feature. Newtonian IGT pick test oil was applied at different film thickness on the application roller and the pull-off force (release force) was recorded using a range of contact nip pressure and nip dwell time. The CFT is confirmed primarily to be a function of the surface roughness for materials of defined surface chemistry. The release force maximum value, the width of the release force peak
and the CFT at the maximum force can all be accurately determined. Fine GCC pigments, for example, gave low surface roughness, low CFT values and high but sharp release force peak. The high sensitivity of this test method enables new insights to be gathered into the nature of the paper surface release properties.
Original languageEnglish
Title of host publicationAdvances in Printing and Media Technology
Subtitle of host publicationProceedings of the 44th International Research Conference of iarigai
EditorsPatrick Gane, Cathy Ridgway
Place of PublicationDarmstadt
ISBN (Electronic)978-3-9870704-7-1
Publication statusPublished - Sep 2017
MoE publication typeA4 Article in a conference publication
EventInternational Research Conference of Advances in Printing and Media Technology - Fribourg, Switzerland
Duration: 10 Sep 201713 Sep 2017
Conference number: 44

Publication series

NameAdvances in Printing and Media Technology
ISSN (Print)2409-4021


ConferenceInternational Research Conference of Advances in Printing and Media Technology
Abbreviated titleIARIGAI
Internet address


  • release force
  • critical liquid film thickness (CFT)
  • surface roughness
  • liquid-void space distribution
  • offset printing
  • GCC pigment coating


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