Gerace, whose foundation is linked to the abandonment of ancient Locri, represents one of the most important ceramic production centers in southern Calabria between the Middle Ages and the modern age (cf. supra, pp. 348 et seq.). The study of the ceramic materials found in the production of Gerace potters in the early modern age, is aimed at the mineralogical and chemical characterization of the mixtures and at the determination of the composition of the pigments used for the pictorial decoration of the majolica. The main purpose was to obtain information on the production processes and on the origin of the raw materials used. Ten ceramic samples and two samples obtained from a single lump of clay, taken in a disused laboratory and fired in an electric oven at 500°C and 1000°C, were subjected to thin section examination under a polarizing microscope. The investigations revealed a carbonate matrix with moderately abundant and rather fine inclusions made up of calcareous microfossils (foraminifera, mainly Globigerine, but also Orbulines, rarer Elphidium and Sponge spicules), micas and subordinate angular grains of quartz and feldspar. Firing temperatures vary from about 800°C to over 900°C and the tendency of the biscuit to lighten as the temperature increases has been noted. The results of the mineralogical, petrographic and chemical analyzes and the fossiliferous association present in the ceramic mixtures are compatible with the sediments belonging to the Trubi Formation, widely present in the Gerace area. The variations found in the ceramic mixtures could be linked to differences in the craft processes, to the variations naturally present in the clayey sediments, in the layers used and in the clay supply area over time. The study of glazes and pigments was conducted on two specimens of Gerace majolica production from the 17th century using portable X-ray fluorescence spectrometry. The two vases, both for apothecary use, but dating respectively to the fifth and ninth decade of the century, were chosen with the aim of having information on the pigments in use in the first and second half of the seventeenth century, to be compared with the indications emerged from other sources. Investigations confirmed the presence of lead and tin in the white pigment, copper in the green pigment and cobalt in the blue one. In the orange and red pigment, instead, a high iron peak is detected. Of particular importance is the study of the red pigment, a peculiar feature of this production which is linked to a persistent use by the potters of the area, of an earthy compound (as a pigment) which could also be applied with a brush, produced with a similar process to that of the bolus, but still to be investigated and clarified.
IndagInI archeometriche prelImInari su alcunI campIonI della produzIone ceramica dI Gerace In età moderna
Sabrina Gualtieri;
2023
Abstract
Gerace, whose foundation is linked to the abandonment of ancient Locri, represents one of the most important ceramic production centers in southern Calabria between the Middle Ages and the modern age (cf. supra, pp. 348 et seq.). The study of the ceramic materials found in the production of Gerace potters in the early modern age, is aimed at the mineralogical and chemical characterization of the mixtures and at the determination of the composition of the pigments used for the pictorial decoration of the majolica. The main purpose was to obtain information on the production processes and on the origin of the raw materials used. Ten ceramic samples and two samples obtained from a single lump of clay, taken in a disused laboratory and fired in an electric oven at 500°C and 1000°C, were subjected to thin section examination under a polarizing microscope. The investigations revealed a carbonate matrix with moderately abundant and rather fine inclusions made up of calcareous microfossils (foraminifera, mainly Globigerine, but also Orbulines, rarer Elphidium and Sponge spicules), micas and subordinate angular grains of quartz and feldspar. Firing temperatures vary from about 800°C to over 900°C and the tendency of the biscuit to lighten as the temperature increases has been noted. The results of the mineralogical, petrographic and chemical analyzes and the fossiliferous association present in the ceramic mixtures are compatible with the sediments belonging to the Trubi Formation, widely present in the Gerace area. The variations found in the ceramic mixtures could be linked to differences in the craft processes, to the variations naturally present in the clayey sediments, in the layers used and in the clay supply area over time. The study of glazes and pigments was conducted on two specimens of Gerace majolica production from the 17th century using portable X-ray fluorescence spectrometry. The two vases, both for apothecary use, but dating respectively to the fifth and ninth decade of the century, were chosen with the aim of having information on the pigments in use in the first and second half of the seventeenth century, to be compared with the indications emerged from other sources. Investigations confirmed the presence of lead and tin in the white pigment, copper in the green pigment and cobalt in the blue one. In the orange and red pigment, instead, a high iron peak is detected. Of particular importance is the study of the red pigment, a peculiar feature of this production which is linked to a persistent use by the potters of the area, of an earthy compound (as a pigment) which could also be applied with a brush, produced with a similar process to that of the bolus, but still to be investigated and clarified.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
