Volcanic tuff was commonly used in many Italian regions, because of availability and workability. Durability, on the other hand, is rather poor, and therefore conservation treatments need to be applied. Research on the interactions among tuff and the products used for consolidation and waterproofing is therefore necessary. The present work gives the results obtained with four different systems, all having a consolidating action and a water-repellent effect, applied to blocks of a volcanic tuff obtained from the remains of an Etruscan wall in the area of Cerveteri, to the north of Rome. The products studied were: a methylmethacrylate monomer, a polymethylmethacrylate, a methylphenylpolysiloxane, and a mixture of ethylsilicate and methylsilane.