USING STEREOSCOPIC AND SEM BACKSCATTER IMAGING FOR STUDYING INK DISTRIBUTION DETAILS ON PAPER AND FIBER SURFACES

A method for studying printing ink distribution details on commerciall y printed paper surfaces is explained, and exemplified by newspaper pr inted in offset. The difference in atomic number between ink pigment p articles and the fibres is sufficient to discern the ink by backscatte r imaging (BSI). Combining this with standard methods for making stere oscopic micrographs allows the study of topographical ink distribution on the individual fibres. Details of the method are explained, and ex amples presented. The ink is found to be located in local depressions on the fibre surfaces. Sharp ''ridges'', often seen on mechanical pulp fibres, will typically carry no ink. The 3D BSI micrographs provide a very useful way of understanding the ink/paper relationship.