I have an old Geographia street map (ca. 1960) which is failing by splitting along the folds. It has been stuck together with Sellotape, but even that's drying out. My idea is to glue the bits to a backing of hardboard (30" x 40") and carefully tease out the dog-eared edges. My concern is that if I was to use water-based adhesive, such as PVA, the hardboard may swell and curl. Possibly 3M spray photo adhesive?