strappo

The term "strappo" in art restoration refers to a technique for transferring wall paintings. This method involves gluing canvas to the surface of a fresco and then carefully pulling away a thin layer of plaster that contains the pigment particles. The bond between the canvas and the fresco must be stronger than the plaster's internal cohesion.1

This process reveals the fresco in reverse, and excess plaster is removed from the back. The thinned pictorial layer is then fixed to a rigid support. However, "strappo" is a radical procedure that can irreversibly alter the original surface character and pigment density, so it is now seldom used. A less intrusive method is "stacco," which retains a thicker layer of plaster.1