Laboratory paper coatings of simple composition, comprising only a single spherical plastic pigment and binder type, were analysed in terms of water-based inkjet print quality. Optical density and gamut of dye colours decreased with increasing pigment size, and followed the binder hierarchy from polyvinyl alcohol (best) to carboxymethyl cellulose to styrene-butadiene latex (worst). For the larger pigment size, density and gamut also decreased with decreasing binder content and increasing coat weight. Colour-colour sharpness was evaluated using four measures of line bleeding, of which mean line width and blurriness were found to be the most useful and well correlated. Both bleeding measures, while following the same binder chemistry hierarchy mentioned above, now worsened with decreasing pigment particle size. This tallies with expectations from capillarity and light scattering, e.g. increasing particle size (in the range studied) increases both liquid penetration rate and opacity, thus resulting in decreased colour richness but increased sharpness.
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