ABSTRACT
Sealants are used to seal joints against rain, air, dust, odours and sound. Joints must be sufficiently wide to accommodate the expected movement, but excessive width wastes sealant, which is costly, and it may slump. Movements are usually small and fairly slow, but where they are restrained by friction, as happens in spigot and socket joints in aluminium certain walling, a slip-stick action occurs and the rapid movement can cause sealants to fail. Plastic sealants form a tough and protective skin by oxidation. Paint prolongs the life, but eventually these sealants harden and tend to crack. Greater stresses are imposed on adhesion to joint surfaces by elastic sealants than by plastic materials and, to avoid adhesion failure, soft plastic sealants are preferred. Acrylic sealants are used for sealing gaps between baths, lavatory basins and wall surfaces. Sealants are made in consistencies suitable for application by hand, gun, by pouring or as a preformed strip or tape.
