Artificial resin obtained through the process of polymerization. Synthetic resins were made available by the chemical industry essentially beginning in the 1950’s and progressively introduced in various operations of restoration, both in response to specific unresolved needs and to substitute many traditional products (although cautiously due to the scarce knowledge of their behavior in time). To classify the synthetic resins is extremely difficult due to both the number synthetic resins (constantly increasing), and for the lack of a precise criteria distinctive among these and plastic materials, that is base polymers and products obtained from working resins with added plasticizers, lubricants, fillers, etc.