Widespread use of a damaging conservation technique has seen many of Italy’s Renaissance frescoes darken and crumble. That degradation can now be stopped in its tracks.
In the 1960s conservators began coating frescoes in clear acrylic polymers to preserve them, but the treatment has had the opposite effect. “The acrylic makes the fresco look brilliant and well preserved initially,” says Piero Baglioni, a chemist at the University of Florence. “But as the plaster can no longer breathe, degradation beneath the coating actually speeds up, due to calcium salt and humidity build-up.”
The iron-based pigments in the frescoes react with the…
