Monitoring mineralogical and porosity transformations in modern Hebron ceramics caused by salt whitening agent using non-invasive methods

• Micro-CT highlights the effects of adding sodium chloride salt on ceramic porosity and the redistribution of pores. • SWIR Hyperspectral Imaging allows the observation of phase changes resulting from variations in ceramic firing temperatures. • SWIR Hyperspectral Imaging presents great potential for determining firing temperatures using non-destructive tools. A field investigation conducted among potters in Hebron (Palestinian Territories) revealed the use of salt in clay pastes to produce white ceramics. An initial study ( Teodorescu et al., 2022 ) sought to understand and explain this phenomenon. In addition to the visible whiteness, the potters also emphasised other qualities, such as porosity. This research aims to explore how the addition of salt influences the material’s properties to meet both the aesthetic and functional criteria valued by the potters. At the outset, raw materials and finished products were sampled directly from workshops in Hebron. A series of test briquettes were then produced in the laboratory following a protocol that allowed for precise control of both salt concentration and firing temperatures, based on the raw materials used by the Hebron potters. The goal was to assess the role of temperature and salt concentration in the development of the material’s pore structure. Firing temperatures were estimated from the reflectance spectral response obtained in the short-wave visible range (400–800 nm) and the infrared range (1000–2500 nm), using a hyperspectral camera (HSI). At the same time, the material’s porosity was examined through X-ray micro-tomography. The results indicated an increase in porosity with increasing temperature. More significantly, the addition of salt led to a redistribution of pores, favouring the formation of macropores. Furthermore, the results revealed that hyperspectral imaging is a highly promising non-destructive tool for estimating the firing temperature of ancient ceramics.