This paper reports an experimental methodof measuring the colour change of wet paint when subject to a well-de5nedshear "ow. Using
a Multi-Pass Rheometer (MPR) anda modi5edcolour spectrophotometer, the e8ect of shear on the colour changes of a red-pigmented
paint were systematically studied. Substantial changes in paint colour during and after shear were observed for certain paint compositions.
Additional direct optical observation on diluted paint samples strongly suggested that the key mechanism associated with the colour change
was the state of pigment agglomerates during shear and the "occulation after shear. A model based on Mie scattering was developed to
give a semi-quantitative prediction of the observed experimental trends.
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