PURPOSE: To reuse a concrete form made of a metal by preliminarily coating the surface of the concrete form and the surface of the timbering support of the form with a paint compsn. forming an alkali removable film and removing concrete bonded after casting along with the film by an alkali aqueous soln.

CONSTITUTION: A concrete form made of a metal and the timbering support thereof are preliminarily coated with a paint compsn. forming an alkali removable film. This paint compsn. is prepared by mixing an acrylic resin emulsion, a water-soluble multivalue metal compd., an alkali soluble resin, a film forming aid and aqueous ammonia and dried after coating to be formed into a continuous film. Concrete bonded after casting is removed along with the alkali removable film by a silicate aqueous soln. with pH9. Therefore, the form can be reused without being damaged.