Preliminary studies for the removal of carbonate deposits from painted ceramics using chemical solutions

Abstract

This study analyzes the changes that painted archaeological ceramics undergo after direct and indirect cleaning treatments applied to remove carbonate deposits. Nine Iberian decontextualized sherds from the Los Villares de Andújar site (Jaén, Spain) were documented: macroscopic examination, digital photography, optical microscopy and scanning electron microscopy – energy dispersive X-ray spectroscopy. Lime putty was then applied to the ceramic surfaces to generate the deposits and several cleaning treatments were pursued. Finally, the changes resulting from the cleaning treatments were documented using the same techniques and procedures. The porosity of the sherds had a major influence on the suitability of the cleaning treatments. Nevertheless, treatments with ethylenediaminetetraacetic acid (EDTA) disodium salt applied by cellulose pulp poultice were more respectful to painted areas compared to immersion, whereas nitric acid solutions altered both polychromies and ceramic surfaces regardless of the application method. The ion-exchange resin, directly applied, presented promising results in uncolored areas.