Exploring the technique of glazing used by the potters of Barcelona

The application of glazes on pottery became common in Western Europe from the late 12th century / early 13th century onwards. However, the process of 'glazing' entails different degrees of complexity which might involve a great variety of raw materials. Accordingly, simple glazing process consists of a single layer applied over the surface of the body, becoming a shiny and transparent coat after firing. The addition of pigments would result in a coloured glaze that can be translucent or even opaque. The more complicated sequence occurs in decorated glazed pottery, where opacifiers, pigments and metals are added to produce an opaque white glaze to enhance the decoration. This glaze is applied to the bisque pottery and manufactured, usually, in a second or third firing. To deepen our knowledge of the glazing technique, we have studied glazes from coarse pottery, cooking ware, polychrome coarse pottery and majolica from Barcelona (13th to 18th centuries AD). The application of the glaze, the thickness, and the composition of glazes (including opacifiers, pigments and/or metals) have been examined, through Scanning Electronic Microscopy (SEM). This study has revealed the high diversity in the glazing technique