The Potential of Microorganisms for the Conservation- Restoration of Iron Artworks

Comensoli, Lucrezia (Swiss Federal Laboratories for Materials Science and Technology (Empa) Dübendorf, Switzerland) ; Kooli, Wafa (University of Neuchâtel, Switzerland) ; Monachon, Mathilde (University of Neuchâtel, Switzerland) ; Albini, Monica (Institute for Nanostructured Material (ISMN-CNR), Rome, Italy) ; Junier, Pilar (University of Neuchâtel, Switzerland) ; Joseph, Edith (Haute Ecole Arc Conservation-Restauration, HES-SO University of Applied Sciences and arts Western Switzerland)

Archaeological iron artefacts encounter serious post-excavation problems when contaminated with salts. Once excavated, exposure to a higher oxygen concentration and lower relative humidity renders the corrosion crust formed during burial no longer stable. In particular, the process is induced by chloride ions and leads to flaking, cracking and the final loss of shape of the object. The MAIA project (Microbes for Archaeological Iron Artefacts) studied microbial metabolisms to explore their potential for the development of innovative and sustainable methods for the stabilisation of corroded iron archaeological objects. Two different approaches were investigated. First, bacterial reduction of iron solid-phases and biogenic mineral formation were studied as a way to replace unstable corrosion products. Several bacterial strains were compared. Spectroscopic investigations with Raman and Fourier transform infrared spectroscopy on iron coupons, nail surfaces and cross sections demonstrated the conversion of the outermost part of the corrosion layer into more stable biogenic minerals, such as vivianite and siderite. The second approach was to study fungi and their metabolic ability with iron. In particular, alkaliphile fungi that tolerate chlorine were studied for their ability to produce biogenic minerals and to adsorb metals in their biomass. Colorimetric investigation and evaluation of the thickness of the corrosion layer demonstrated that fungi are good candidates for developing bio-cleaning methods for corroded iron, permitting the selective removal of the unstable and powdery corrosion layer without damaging the original metal surface. This study details these approaches and explores the possibilities of their exploitation for development of innovative and more sustainable treatments for the conservation-restoration of corroded iron.

Conference Type:
full paper
Design et Arts visuels
Unité de recherche en Conservation-restauration de la Haute Ecole Arc - UR-ARC CR
Conservation - Restauration
Neuchâtel, Switzerland, 2-6 september 2019
Neuchâtel, Switzerland
2-6 september 2019
9 p.
Published in:
Metal 2019, 9th interim meeting of the ICOM-CC metals working group
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 Record created 2020-04-01, last modified 2020-10-27

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