Newsprint smearing - an industrial problem studied with the nuclear microprobe

Six newsprint samples, selected with respect to their different smearing pr operties, have been investigated with the PIXE-technique with a nuclear mic roprobe. In addition, local basis weight was simultaneously measured with t he off-axis STIM technique. The newsprint samples were all printed nominall y with the same amount of cyan ink (approximate to 2% Cu). The normalised C u-yield distributions differ both with respect to spread and slope of the t ail. Correlations have been found between the spread and global paper param eters like surface roughness and porosity. Of major interest for the smeari ng problem is the correlation found between the momentary smearing paramete r, set-off and the micro distribution parameters. Correlations between basi s weight and ink distributions are discussed and a possibility to measure t he different penetrations of pigment particles and oil in the paper structu re is pointed out. (C) 1999 Elsevier Science B.V. All rights reserved.