Archaeological Ceramics Artefacts Degradation: Diagnostic Investigations and Chemical Cleaning Procedures

A detailed knowledge of the micro-chemical and micro-structural nature of an archaeological artefact is critical in finding solutions to problems of restoration, conservation, dating and authentication in the art world. The identification of degradation products and the possibility to find appropriate treatments whereby degradation processes may be either arrested or reversed is one of the most important goals of surface science studies related to heritage conservation. A complex problem faced in the conservation of ancient artefacts is represented by the cleaning of the thick encrustations from the surface of historical and artistic ceramics artefacts. The removal of encrustations and hard soiled deposits is an essential intervention, but yet controversial because the encrustations hinder significant decoration details and obscure the historical, social and artistic value of an ancient object but their removal could be harmful to the object itself. The multi-disciplinary approach, which is commonly needed, requires a combination of both conventional bulk and surfacesensitive techniques, suitably adapted to the specificity of materials of archaeological interest, e.g. non destructive characterization, non-invasive restoration, prevention of future degradation. A selection of Greek, Roman, Medieval and post-Medieval (XIII to XVII century) ceramic artefacts from archaeological excavations in different Italian sites were investigated by means of scanning electron microscopy combined with energy dispersive spectrometry (SEM+EDS), optical microscopy (OM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD). The removal of the calcareous coherent deposits disfiguring the finely decorated glazes was carried out by using a reliable and effective cleaning procedure, based on a cationic exchange resin working in strictly controlled conditions of temperature and humidity.