Laser Selectivity on Cleaning Museologic Iron Artefacts

ABSTRACT Three distinct techniques were used for the clean ing of Fe alloys objects that present surface corrosion. These objects are presen tly kept in a museologic space. The techniques used to remove the corrosion were mechanical, chemical (EDTA solution) and LASER (pulsed CO2 and Nd:YAG – Q-Switch), a nd their efficiency and selectivity compared. The chemical characterisation of the metallic surface and the evaluation of the cleaning degree of the Fe objects were done by transmission 57Fe Mossbauer spectroscopy. The results of the Mossbauer sp ectroscopy presented here, togeth er with optical microscope observations of the original a nd cleaned objects suggest that: - The mechanical process of cleaning does not allow for the total removal of corrosion, reaching easily the substratum and so causing mechanical damage on the object. - The cleaning methods using EDTA in confined environment and high control of the experimental conditions, remove the corrosion produc ts efficiently, without damaging the surface of the object. - The cleaning methods using LASER although not achieving the complete removal of corrosion, showed clear characteri stics of selectivity in a give n range of operating parameters. 1. INTRODUCTION