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Archaeological ceramics are among the most studied artifact categories since they can refer to both social and economic traditions of past communities. Investigations usually point at determining the production technology and special attention has been given to the firing conditions. This poster presents the intricate knowledge system of pottery production occurring in Norway in the Bronze Age (1300–900 BCE). To this aim, aliquots of clays sampled in Norway, Germany and Poland were fired in an electric furnace at 500, 550, 600, 700, 800 and 900℃ and successively analyzed by colorimetry, XRD and FTIR-ATR to determine modifications in term of structure and mineralogical composition. Temperatures were chosen based on pre-existing knowledge of ceramic technology in the geographical region of interest in that period [1].
Results were compared with those obtained on a set of ten ceramic fragments dated to the Bronze Age at the site of Hunn in Eastern Norway. The aim was to estimate the temperature used in the production of these prehistoric ceramics exhibiting typological similarities with contemporary finds from Southern and Central Sweden as well as Northern Poland [2].
Due to the abundance of the thermally stable grain minerals such as quartz and feldspar, the study of the clayish fraction through XRD resulted particularly hostile, while FTIR-ATR confirmed its usefulness in investigating ceramics and ceramic-related materials. A progressive modification of the color of the fired material, turning towards a reddish hue, was due to the gradual formation of iron oxide (Fe2O3), starting from 700 ℃. In parallel, carbonates decompose and weak features due to CaO appeared. In addition, small amounts of chlorite, a phase decomposing at 600–650 ℃, were found through the petrographic analysis of some archaeological sherds highlighted, . However, its structural similarity with other clay minerals and the abundence of silicate phases, made the identification of chlorite by XRD and FTIR not possible in the fired clays.
Despite this, the experiment helped to strengthen the hypothesis about the technological correspondence of similar ceramics in Eastern Norway and Western Pomerania in the Bronze Age, as the results seem to indicate that the Bronze Age ceramics were fired at a temperature not higher than 700 ℃, more probably ranging between 600 and 650 ℃.
[1] H.M. Hop Wendelbo, Keramikk fra norske bronsealdergraver: En studie av morfologi, kronologi, forbindelser og deponeringspraksiser i tidsrommet 1700-500 f. Kr., 2020
[2] T. Eriksson, Kärl och social gestik: keramik i Mälardalen 1500 BC-400 AD, Uppsala universitet/ Riksantikvarieämbetet, 2000