On the bursting of viscous films

In this Brief Communication we consider the shape of the rim of a very visc ous film retracting with velocity U-0 under surface tension. We demonstrate that the film has a growing rim if and only if the Stokes length v/U-0 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 f ilm is perfectly flat. These results are discussed in light of recent exper iments on the bursting of viscoelastic films. (C) 1999 American Institute o f Physics, [S1070-6631(99)01202-7].