Restoration of the Florentine Frescoes using nanoparticles and microgels

Working on irreplaceable, priceless artworks brings special challenges and rewards. In this presentation I will describe the development of modern technologies for art restoration and cleaning based on fundamental physical chemistry. The discussion will be illustrated with examples of our restoration work.

Professor Enzo Ferroni (1921-2007) at the University of Florence, was one of the first scientists to apply a scientific approach to the conservation of cultural heritage. After the catastrophic flood of the river Arno that hit Florence in 1966, Ferroni began to collaborate with restorers and conservators in order to help them save some of the masterpieces of Italian Art. Since then, we have built on these foundations to develop advanced applications of physical chemistry to art restoration.

In the past years we pioneered the synthesis and the application of several advanced systems for the cleaning and consolidation of works of art. The main systems developed so far are hydroxide nanoparticles, microemulsions and chemical/physical gels.

i) Nanoparticles. Calcium and barium hydroxide nanoparticles offer versatile and highly efficient tools to invert the degradation processes altering wall paintings, or to de-acidify and protect paper and wood. These inorganic consolidants are highly chemically stable and preserve wall paintings ensuring long-lasting effects without the side effects produced by polymer coatings. Calcium hydroxide ensures the highest physico-chemical compatibility with the work of art and should be preferred when degradation results from the loss of calcium carbonate. The presence of sulfate salts as a contaminant can inhibit the consolidation effects. Innovative formulations based on calcium and barium hydroxide nanoparticles overcome these limitations due to their synergistic action.

ii) Micelles, microemulsions and chemical/physical gels. The cleaning or the removal of coatings from pictorial surfaces can be achieved by using very efficient colloidal systems. Primarily microemulsions and micellar solutions and also smart gels with embedded microemulsions or micellar solutions.
Illustrative examples of the applications of these systems in recent restoration workshops will be reported.