Physical and mechanical properties of ceramics: insights into raw material selection in prehistoric pottery production in Croatia

This study investigates the physical and mechanical properties of ceramics, with a particular emphasis on the influence of clay composition and tempering materials on ceramic point load strength and the technological process involved in ancient ceramic production. A combination of analytical methods was employed, including X-ray diffraction (XRD), optical microscopy, laser granulometry, Atterberg limits, shrinkage evaluation, and the point load index test. Two clay types; sandy clay and inclusion-poor clay, alongside four tempering materials; calcite, sand, grog, and vegetal material, all commonly used during prehistory in Croatia, were analysed. The results show that the inclusion-poor clay requires more complex preparation and firing but results in stronger ceramics. In contrast, sandy clay, which is easier to process and fire, produces ceramics with lower strength. The effect of tempering materials is clay-dependent, with a more significant impact observed in inclusion-poor clay. These results emphasize the critical role of clay in shaping the production process and ceramic properties, highlighting the need to adapt technological process to clay characteristics. Communities selecting sandy clay prioritized ease of preparation, while those using inclusion-poor clay valued its superior functionality despite greater technological demands.