Adhesives, also known as glue, cement, mucilage or paste is any non metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. Sealant is a liquid, viscous material that upon applied on the surface changes to solid and prevents passage of liquid/gas/vapor through the joint. It has three basic functions. It fills a gap between two or more substrates. It forms a barrier through the physical properties of the sealant itself and by adhesion to the substrate. It maintains sealing properties for the expected lifetime, service conditions and environments. Sealant's primary job is to seal and secondary to bond, hence sealants are adhesives too. They add to the structural strength of the assembly. Polyurethane Foam spray is dispensed as a frothy liquid which expands and cures into a solid foam (like Thermocol) insulation and sealant.