Study of the firing type on the microstructure and color aspect of ceramic enamels

Highlights: • We investigated Influence of the firing type on the microstructure and color aspect of ceramic enamels. • Infrared heating promotes thermal gradients that act as thermodynamic forces. • Infrared heating gave a better rendering of the pure red color. The enameling is a technique of decoration whereby objects or flat surfaces are covered by a vitreous glaze that is fused by intense heat to create a brilliantly colored decorative effect. It is an art form noted for its brilliant, glossy surface, which is hard and long-lasting. It is known that the firing method used to produce enamels plays a very important role in the color rendering. The objective of this work was to compare enamel decors obtained with two kinds of firing systems: a conventional furnace and infrared emitters, in order to gain better understanding and control the development of new colors. The results highlighted a deep impact of the heating technique on the final color due to the formation of layers having very different chemical phases and textural properties. The obtained materials have been characterized by different physico-chemical techniques such as infrared spectroscopy, XRD, SEM and EDS. Infrared heating allowed the production of nearly pure red enamel decor with a shiny aspect which was not the case with conventional furnace firing. The paper also showed that color design of different color shades would be possible by using hybrid systems allowing a fine tuning of thermal gradients during the heat treatment.