Precursor content assessment and its influence on the optical interference of a nano-sized mica-hematite pearlescent pigment

The present paper investigates the influence of the precursor content on the pearlescent effects of a nano-sized mica-hematite pearlescent pigment. A reliable and efficient model is developed to estimate the required precursor in order to completely deposit hematite nano-particles on to mica flakes. Homogeneous hydrolysis standard method is applied to synthesize the pigment where iron sulphate(III), urea and mica are considered as coating precursor, precipitant and substrate, respectively. To characterize the as-synthesized pigments, scanning electron microscopy, energy dispersive spectroscopy and colorimetry have been used. The results indicate that the required precursor content for the complete coating of mica platelets only depends on mica-specific surface area. Moreover, any deviation in the calculated optimum amount of the precursor would degrade the optical interference of pigment and consequently would reduce the pearlescent effect.