Scientists from Milan University have shown that the bacterium
Pseudomonas stutzeri, applied with water on cotton wool, can eat through
80% of the glue in about 10 hours.
Chunks of the 14th- and 15th-century series of frescoes at the
Camposanto cemetery were removed for repair and restoration in the 1950s.
Part of the cemetery had been badly damaged by bombing during the second
world war.
But as a result of the strappo technique, using canvas and organic glue
to pull the frescoes from the wall intact, one of the paintings vanished
under a layer of glue which could not be removed without damaging the
surface.
For years experts tried to solve the problem, and last year they were
accused of destroying a section of the fresco by using a strong solvent.
But in the recent experiment the bacterium successfully uncovered a 26
sq metre area of the fresco called the Conversion and Battle of Saint
Efisio, by the artist Spinello Aretino.
”Experts had tried everything,” said Claudia Sorlini, a member of
Milan University’s microbiology team.
”If we hadn’t discovered this technique, people would not have seen
this fresco again.”
She said the bacterium they used was found in the soil, and the new
technique could slash the restoration costs by a third.
City officials expect to return the restored frescoes to the cemetery
for public viewing next year.
Now experts can apply the technique to more of the original 1,500 sq
metres of fresco, painted by Taddeo Gaddi and such lesser known artists as
Francesco Traini and Bonamico Buffalmacco.
It is highly valued as one of the largest fresco cycles in the world. — Â