Colors on fire: reconstructing the change of color hues in firing of experimental briquettes

Color change is often used as a proxy for the mineralogical transformations occurring in pottery according to their firing temperature. In this study we employed the non-destructive technique of Visible Near Infrared Spectroscopy (VNIR) to obtain a quantitative color recording on fired clay briquettes. These were prepared using clayey raw materials collected from northern Peloponnese and western Greece. This material has already characterized in terms of their chemical and mineralogical composition as well as some of their physical properties. The calcareous (or non-calcareous) composition of the raw materials is well mirrored in the VNIR color recordings of the experimental briquettes. The results obtained showed that the use of VNIR provides a more accurate, and reproducible approach, which can automate color recording in ancient artefacts, enabling a higher throughput and a fast screening and grouping. This was tested by applying the method on ancient pottery and treating it as unknown samples.