Strappo is the name given to the technique for removing mural paintings.
First, several layers of cloth are applied to the mural painting, previously soaked in water-soluble organic glue.
When the fabric is dry, it is removed from the wall using a chisel and hammer, the painted layer coming off with the cloth.
The cloth is packed and taken to the museum, where the paintings are transferred to a new support. The organic glue is diluted with hot water to separate the cloth from the layer of paint, as if were a decal.