Polyvinyl alcohol (PVAL) -CH2-CH(OH)-CH2-CH(OH)- High molecular weight substance, soluble in water, to which strong viscosity and emulsifying properties are imparted. It is slightly soluble in organic solvents. Uses Thanks to its excellent adhesive properties and high reversibility in water, it is widely used both as a glue and as an impregnating agent for porous materials such as: wood, paper, plaster, plaster, terracotta, etc., and as a reversible protective layer (release agent for resin). Its aqueous solutions, which have film-forming properties, can be attacked by microorganisms and moulds. Therefore they must be protected.