DuraSeal™ is a new, durable heat and solvent-resistant stretch film that claims substantial advantages over common laboratory stretch films. Its superior heat-resistant feature allows for containers to be incubated in boiling water baths without suffering the characteristic "melting" of paraffin-based alternatives. Because DuraSeal™ is polyethylene based and free of any adhesives, it resists essentially all organic solvents and caustic agents, e. g. aliphatic, aromatic and chlorinated solvents as well as strong acids and bases. The film is 0.0015" (0.04 mm) thick and can be elongated 500-800% before breakage, minimizing the incidence of film tearing during stretch sealing. DuraSeal is easy to use. There is no interleaf paper to strip away. Just stretch the film symmetrically over a container opening and the film contracts inwardly around the opening or neck of the container to provide a drum tight water proof stretch seal. The film clings to itself, especially after stretching. The free edges of the film may be stretched around the container to secure the edges.