By suspending small amounts of solvents in nanoscale droplets, chemists have found an environmentally safer method of cleaning centuries-old frescoes and saving them from the unintended consequences of previous restorations.
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The preservation of historic frescoes often involves firming up the paint and slowing its degradation by oxygen, light, and air pollution. In the 1970s, synthetic resins seemed like an ideal fix. Conservators began coating frescoes with protective layers of these acrylic polymers. However, the use of the synthetic chemicals created unforeseen problems, says Piero Baglioni, a chemist at the University of Florence.