Abstract: A hole, particularly an accidental perforation, is closed by manoeuvering a bladder (g) into the hole employing a hollow rod (f) on which the bladder is mounted at one end. An operator operating from the other end of the rod actuates a device such as a triggered valve to cause the components of a settable foamed plastics material to pass (via tubes b and rod f) from their sources (in a) to fill the bladder (g) so that it closes the hole. The settable foamed plastics material is preferably polyurethane foam. The bladder may be of natural or synthetic rubber and may be protected against tearing by a textile envelope. The sources of foamed plastics material may be either in a portable kit (a) or rupturable containers within the bladder (g) or rod (f).