The analogy between elastic solids and viscous fluids is exploited to analyze the collapse of a spherical cavity or void in a thin viscous film, and the initiation of a cavity at a spot on a solid boundary. The analysis shows why the concept of stress-waves from implosions of cavities would not be expected to produce surface damage. Application of crack theory in the second instance accounts for a source of transient high surface stress in the process of cavity formation.Presented at the 47th Annual Meeting in Philadelphia, Pennsylvania May 4–7, 1992