The technology used to apply the label to the recipient also determines the nature of the paper. The traditional “wet glue” method requires papers with good resistance to absorption on the rear. On the other hand, more recent labelling machines require self-adhesive papers or films, which can be supplied in sheets or rolls, in accordance with the configuration of the labelling machine. Self-adhesive products involve three parts: the frontal label (the part that is visible on the outside), the adhesive (permanent or removable) and the support part (the film attached to the rear). To make a material adhesive, a process called converting is used.