Project: Looking for new insight into the fading mechanism of Prussian Blue by FF-XANES and micro-FTIR 2D mapping of Fe(III)/Fe(II) and bridging cyanide on original and model paintings

During the restoration treatment of 18th C. Danish paintings a visual examination by the Conservation Department indicated that extensive fading of the original blue colour had taken place in areas exposed to light while still preserved in areas covered by the frame. Initial analyses were done at CATS as well as during a MOLAB-campaign. The aim of the current continuation of the project is to increase the understanding of the redox process of the mixed-valence pigment Prussian blue (PB) (FeIII4[FeII(CN)6]3∙xH2O/ KFeIII[FeII(CN)6]∙xH2O) in oil paints by evaluating the distribution of the corresponding alteration products in artificially aged PB paint models and in micro-samples from discoloured areas of 18th century paintings.

The synchroton radation will help us understand the mechanisms in the fading of preussian blue.

Researchers: Letizia Monico, Costanza Miliani, David Buti, Anna Vila and Annalisa Chieli from Universita di Perugia (Italy) and CATS.