(f) adhesion systems and/or plumbing systems in which (i) a pre-polymer such as an epoxy resin pre-polymer, e.g. the reaction product of epichlorohydrin and bis-phenol-A or a cross-linkable vinyl polymer such as a low molecular weight polyacrylic acid-polyacrylamide co-polymer, (ii) optionally a cross-linking agent such as a melamine-formaldehyde cross-linker and (iii) a curing catalyst are brough