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Laser selectivity on cleaning museologic iron artefacts

Authors: Pereira, Gilberto; Pires, Margarida; Costa, Benilde F. O.; Costa, Fernanda

Ref.: Proc. SPIE-Int. Soc. Opt. Eng. 6346, 63461G-1-0 (2007)

Abstract: Three distinct techniques were used for the cleaning of Fe alloys objects that present surface corrosion. These objects are presently 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), and 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 spectroscopy presented here, together with optical microscope observations of the original and 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 products efficiently, without damaging the surface of the object. - The cleaning methods using LASER although not achieving the complete removal of corrosion, showed clear characteristics of selectivity in a given range of operating parameters.

DOI: 10.1117/12.738153