The application of paint to a substrate, processing of some food items, manufacture of many cosmetic products, and application of refractory coatings on metal casting moulds all depend on the development of suitable rheological characteristics, such as viscosity and thixotropy, in the product. In practice, the optimisation of composition, in terms of both rheological behaviour and final properties, often is found by trial-and-error, which can be quite expensive and time consuming. A more efficient approach is to use a statistical model to evaluate the effects of composition on rheology and other properties. In this paper, the basic concepts of mixture design and analysis are applied to the formulation of a refractory coating, with illustration by a worked example. Experimental data of coating viscosity vs composition are fitted to the model.
