A glaze is a finishing coating layer melted and fused permanently with the surface of clay through a crystalline structure during firing. Aluminium is an important constituent in the glaze mix, as it acts as a stabiliser, allowing the glaze to attach firmly to the ceramic substrate. Engobe is an interlayer that sometimes is applied first on a substrate under the glaze layer in most ceramic tiles, to increase the substrate’s opacity and attenuate physical–chemical differences, increase the compatibility between the substrate and the glaze and reduce defects on the ceramic material’s surface (Dal Bo et al., 2014). Depending on the glaze content and the desired finishing, the surface finish of glaze can be glossy or matte, and it can be transparent, opaque, white or coloured. Different types of glazes and engobes can be produced by varying the proportions of the constituents, such as alumina and silica, e.g., increasing the alumina and decreasing the silica produces a matte glaze.