New techniques for ancient materials

The aim of this project is to shed more light on the physico-chemistry of Prussian blue in cultural heritage artefacts and on its fading behavior, which is associated with a redox mechanism that is still far from being understood.

Factsheet

  • Lead department Bern University of the Arts
  • Institute Institute Materiality in Art and Culture 
  • Research unit Material analyses
  • BFH centre BFH Centre for Arts in Context
  • Funding organisation SNSF
  • Duration 01.03.2012 - 31.07.2019
  • Project management Claire Gervais
  • Head of project Claire Gervais

Situation

From a material point of view, objects of cultural heritage ‘have it all’: they are complex, composite, often precious and fragile, generally with an unknown material history. Their conservation is, however, of primary importance, as they offer testimonies of human history, culture and art. The analysis of cultural objects requires the use of state-of-the-art, non-destructive techniques that maximize the amount of information usually contained in a tiny, precious sample generally composed of a complex and composite material. Synchrotron techniques and computational tools are two promising approaches to reach this goal. Although powerful and employed more and more in the cultural heritage community, their sophistication requires an expertise that may hamper their full exploitation.

Course of action

In this research, we intend to focus on the characterization of the physico-chemical pro cesses taking place during the degrada - tion, specifi cally by means of state-of-the-art synchrotron and computational techniques. The main underlying idea is to provide general, fundamental knowledge about the materials of which the cultural objects are constituted, about their degradation processes and their sensitivity to the environment – knowledge which in turn can be used by conservation scientists to examine specific cases efficiently.

Result

Project #1. Analysis of pigment-substrate-environment interactions: Light and anoxiainduced fading of Prussian blue. Contradictory fading behaviour has been observed for Prussian blue objects subjected to intense light or anoxia exposure. This apparent lack of coherence can be explained by the capacity of the substrate to modify the Prussian blue structure and its fading behaviour. To understand these processes in Prussian blue paper systems, we will analyse model samples by the following series of steps: a) Characterization of the structure of Prussian blue powder on substrate, before and after light/anoxia exposure, b) Quantification of cellulose and lignin degradation of paper, c) Visualization of the distribution of Prussian blue within the paper matrix. Project #2. Porosity and transport phenomena in archaeological corroded iron. Studies on long-term altered systems have shown that iron corrosion products developed in soil or in anoxia are organized in multilayers with a thickness of several hundred microns to some millimeters depending on their age. This project aims at developing an approach based on the coupling of highresolution 3D visualization of corroded iron layers with numerical simulations of diffusion and transport. We will develop porosity characterization and simulation tools based on X-ray computer tomographic data of ar chaeological and model iron artefacts.