HELIX (Investigating metal bioremediation for the preservation of historical metal artworks)

The HELIX project, developed at the Haute Ecole Arc Conservation Restauration, in collaboration with the University of Neuchâtel, the University of Bologna, and Arc' Antique conservation and research laboratory, aims to develop green formulations to clean altered and tarnished surfaces from copper, iron, and silver artworks. The goal is to propose a sustainable method that is conscious of the challenges in the conservation field while limiting the risks for the artwork itself, the operator, and the environment.          

The ability of some microorganisms (fungi, bacteria) are exploited as well as green solvents and gels employed. Corrosion products or altered  organic coatings are then removed from tarnished metallic surfaces.This project gives birth to two PhD theses, focused respectively on the use of hydrogels and organogels from renewable sources.  

Microorganisms are thus selected and incorporated into hydrogels derived from biological sources (agar from seaweed, gellan gum from bacteria). In parallel, non-aqueous solvents (e.g., Deep Eutectic solvents – DES) and green thickening agents (e.g., poly β-hydroxybutyrate – PHB) are selected and employed to prepare bio-based organogels. The stability, the texture, and the application of such formulations are studied and their efficiency assessed on corroded metal coupons. Their performances are compared to commonly used chelating agents (e.g., EDTA) or mechanical methods, thanks to various analytical and imaging techniques (SEM-EDS, FTIR and Raman spectroscopy, gas chromatography, XRD, etc.). The most promising formulations will be tested on genuine artworks representing targeted degradation features.

Collaborations :

• Laboratory for bioanalytical chemistry
• Haute Ecole Arc, Conservation Restauration, HES-SO
• Laboratoire Arc'Antique, Nantes, France
• University of Bologna, Italy
• Haute Ecole d'Ingénierie et d'Architecture de Fribourg, HEIA-FR