On the bursting of viscous films

In this Brief Communication we consider the shape of the rim of a very viscous film retracting with velocity U0 under surface tension. We demonstrate that the film has a growing rim if and only if the Stokes length ν/U0 is smaller than the radial extent of the film. If the Stokes length is larger than the radial extent of the film the retracting edge has no rim and the film is perfectly flat. These results are discussed in light of recent experiments on the bursting of viscoelastic films.