A technique is presented whereby the distribution of ink pigment within the surface topography of a newsprint sheet may be quantified. A fluorescent ink was applied to a range of newsprints using an IGT AIC2-5 laboratory printing unit. Ink distribution and the surface topography of the sheet were imaged simultaneously using a confocal laser scanning microscope. The distribution of the ink within the surface topography of the newsprint sheet was determined using image analysis techniques. Most imprinted regions occurred beneath a reference surface fitted to the mean sheet surface. Depressions beneath the reference surface that were imprinted were deeper and broader than those that were printed. Also the edges of the unprinted depressions were higher than the mean surface height, increasing their total range in topography and indicating that they may be clustered around large and prominent fibres at the paper surface. A value called the mean inaccessible surface was defined as the difference between the mean distance to the sheet surface beneath the reference surface and the mean distance of the ink pigment beneath the reference surface. This measure showed some relationship to print quality ranking. The technique was able to distinguish a number of notable differences between newsprints of good and poor print quality.
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