  When a flexible plate is peeled off a thin and soft elastic film bonded to a
rigid support, uniformly spaced fingering patterns develop along their line of
contact. While, the wavelength of these patterns depends only on the thickness
of the film, their amplitude varies with all material and geometric properties
of the film and that of the adhering plate. Here we have analyzed this
instability by the regular perturbation technique to obtain the excess
deformations of the film over and above the base quantities. Furthermore, by
calculating the excess energy of the system we have shown that these excess
deformations, associated with the instability, occur for films which are
critically confined. We have presented two different experiments for
controlling the degree of confinement: by pre-stretching the film and by
adjusting the contact width between the film and the plate.
