Detection of forgery in ancient ceramic pottery aided by measurement of thermophysical properties

The ancient ceramics are a class of artefacts intensely affected by cases of art forgery. Faux ceramic wares can be the outcome of miscellaneous assemblage of genuine and fake fragments or may be forged from scratch. Among non destructive approaches for detecting counterfeit objects, thermal methods allow to get very revealing outcomes, especially when based on non invasive techniques such as infrared thermography. This technique is applicable directly on-site by studying the temperature trend over time to identify areas with abnormal thermal behaviour. The possibility to develop an analytical technique to facilitate the recognition of the authenticity of all or part of the ancient vases, based on the detection of thermophysical parameters, is considered. This paper illustrates the determination of fundamental thermophysical properties such as emissivity and thermal diffusivity on an assortment of ceramic samples dating between 5th and 1st century B.C.. In particular a procedure for the evaluation of thermal diffusivity centred on the standard laser-flash method is proposed. The second phase of the research is focused on the analysis of the superficial layers of the artefacts. In particular the effusivity parameter is used to obtain a correlation index between the glaze layer and the substrate of painted crockery. The determination of thermophysical parameters of ancient pottery by thermal methods is not aimed to replace the currently used techniques based on mineropetrographyc approaches, but can surely integrate them, particularly at the first stages of investigation.