A colorimetric technique for assessing the mixture quality of fine particle mixtures

As part of a containing study of the mixing of cohesive powders, late/pigment mixtures were created using either a pestle and mortar or a Lödige mixer.The fine pigment particle `coat' the coarser talc particles, and as the pigment is progressively distributed, so the colour changes.Electron microscopy failed to reveal significant variation in pigment distribution, but comparison of the samples using a KCSIS spectrophotometer gave a satisfactory quantitative assessment of mixture quality.