Microorganisms are the main cause of paper decay. The behavior of molds was studied to determine whether sealing by lamination stops microorganic activity or whether the polymer material acts as a substratum for mold growth. Different types of paper were laminated with different types of films and infected with molds. In the course of 4 to 12 months of observation, inferior quality paper showed the presence of mold colonies. After these tests, disinfectants were added to the glue used for restoration. See also AATA 20-1927 on biodeterioration of surfaces.