A Comparison of the Errors in the Determination of Ink Strength by Various Methods of Specimen Preparation, Measurement and Analysis

NPIRI has introduced a new standard bleaching white in North America for use in evaluating the strength of an ink by creating a pastel tint by diluting an ink or flush with the bleach. While standardizing on the composition of the bleaching white may improve the reproducibility of a given methodology it does not address all of the remaining variables. The methods by which one prepares the specimens, measures the optical properties and analyzes the measurement data are equally critical. Since strength is an economically important property of an ink, a full understanding of the correspondence between these methods is imperative. This report documents some preliminary findings using statistical experimental design to assess and identify the critical sources of errors and differences in the various methods of strength determination.