Two bentonites (M and N) and a sepiolite were used for the cleaning of sulfated black incrustations from stonework and for the desalination of marble facing on indoor walls of Venetian monuments. Cleaning efficiency of bentonite N appears to be very good, comparable to if not better than sepiolite. Scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analysis showed the presence of recrystallized gypsum and carbon on the surface of the cleaning pack, detached from the incrustations. Bentonite N and sepiolite have equivalent desalination properties, as tested by conductimetric measurements.