June 1, 2007 — A salad dressing-like mixture of water, a bit of oil and a sugar-like molecule can safely clean ancient frescoes, according to a new nanotechnology research.
Scientists at the University of Florence, Italy, have discovered that the oil-in-water microemulsion — basically tiny droplets of oil suspended in water — can penetrate a painting’s pores and scrub away grime and acrylic resins.
The potion has proven particularly effective in cleaning frescoes that had been coated in thick layers of paraloid, an acrylic copolymer widely used by conservators in the 1960s. While the paraloid was intended to offer a protective coating for artworks, it turns out the aging of the acrylic, and reactions with calcium salts beneath the coating, produce a disastrous effect decades after the treatment.
"All the colors, especially the background, appear darker and the coated surface is very shiny," chemist Piero Baglioni and colleagues at the University of Florence wrote in the current issue of the American Chemical Society journal, Langmuir.
Previously, organic solvents, traditionally used in restoration, have been ineffective in removing the acrylic copolymer.
"Conventional techniques can remove polymeric material at the surface, but they are almost completely useless in cleaning paraloid from the porous structure of the frescoes. In this case, we found that something like salad dressing can be a great alternative," Baglioni told Discovery News.
The key compound in creating the microemulsions is a sugar-like molecule that makes it possible to mix water and oil — a process that doesn’t occur naturally.
