The simultaneous effect of raw materials (A, B and C) on physical and technological properties of brick compositions was studied. This investigation was carried out using the statistical design of mixture experiments. Ten mixtures of three raw materials were selected and used in the experiments design. Those mixtures were processed under conditions similar to those found in the ceramics industry. Fired body characterisation results were then used to iteratively calculate statistically significant and valid regression equations (trace plots), relating linear firing shrinkage, open porosity, fired bending strength and water absorption with the proportions of raw materials. The microstructures of some selected samples were studied using scanning electron microscopy. Mixtures with high clay B contents were most adequate to produce, under constant processing conditions, a brick with specified properties. The microstructures are characterized by a low closed porosity and absence of vitreous phase.