A rectangular film is clamped at the opposite ends before being inflated into a blister by an external pressure, p. The bulging film adheres to a constraining plate with distance, w0, above. Increasing pressure expands the contact area of length, 2c. Depressurization shrinks the contact area and ultimate detaches the film. The relation of (p, w0, c) is established for a fixed interfacial adhesion energy.