title: Study of corrosion in archaeological gilded irons by Raman imaging and a coupled scanning electron microscope-Raman system.
abstract: In this work, analytical and chemical imaging tools have been applied to the study of a gilded spur found in the medieval necropolis of Erenozar (Bizkaia, Spain). As a first step, a lot of portable equipment has been used to study the object in a non-invasive way. The hand-held energy-dispersive X-ray fluorescence equipment allowed us to characterize the artefact as a rare example of an iron matrix item decorated by means of a fire gilding technique. On the other hand, the use of a portable Raman system helped us to detect the main degradation compounds affecting the spur. Afterwards, further information was acquired in the laboratory by analysing detached fragments. The molecular images obtained using confocal Raman microscopy permitted us to characterize the stratigraphic succession of iron corrosions. Furthermore, the combined use of this technique with a scanning electron microscope (SEM) was achieved owing to the use of a structural and chemical analyser interface. In this way, the molecular characterization, enhanced by the magnification feature of the SEM, allowed us to identify several micrometric degradation compounds. Finally, the effectiveness of one of the most used desalination baths (NaOH) was evaluated by comparing its effects with those provided by a reference bath (MilliQ). The comparison proved that basic treatment avoided any side effects on the spur decorated by fire gilding, compensating for the lack of bibliographic documentation in this field.This article is part of the themed issue 'Raman spectroscopy in art and archaeology'.
authors: Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain marco.veneranda@ehu.es.
authors: Marco
authors: M
authors: Veneranda
authors: Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain.
authors: Ilaria
authors: I
authors: Costantini
authors: Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain.
authors: Silvia Fdez-Ortiz
authors: SF
authors: de Vallejuelo
authors: Arkeologi Museoa/Archaeological Museum of Bizkaia, Calzadas de Mallona 2, 48006 Bilbao, Spain.
authors: Laura
authors: L
authors: Garcia
authors: Arkeologi Museoa/Archaeological Museum of Bizkaia, Calzadas de Mallona 2, 48006 Bilbao, Spain.
authors: Iñaki
authors: I
authors: García
authors: Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain kepa.castro@ehu.es.
authors: Kepa
authors: http://orcid.org/0000-0002-9931-7889
authors: K
authors: Castro
authors: Department of Geography, Prehistory and Archaeology, University of the Basque Country (UPV/EHU), PO Box 450, 01080 Vitoria-Gasteiz, Spain.|Unesco Chair of Cultural Landscapes and Heritage, University of the Basque Country (UPV/EHU), PO Box 450, 01080 Vitoria-Gasteiz, Spain.
authors: Agustín
authors: A
authors: Azkarate
authors: Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain.|Unesco Chair of Cultural Landscapes and Heritage, University of the Basque Country (UPV/EHU), PO Box 450, 01080 Vitoria-Gasteiz, Spain.
authors: Juan Manuel
authors: JM
authors: Madariaga
keywords: NaOH desalination treatment; Raman imaging; akaganeite; coupled scanning electron microscope–Raman system; iron corrosion; silver chloride