A method is described for introducing perforations into a sheet (1) of laminated material that includes a layer of hydrophobic gel (4). The method involves contacting perforating elements (13) with the sheet and subjecting the sheet (1), at least in the regions contacted with the perforating elements (13), to high frequency mechanical vibrations, eg using a sonotrode (14). The hydrophobic gel (4) is most suitably a silicone gel, and the perforated laminate may be utilised in a wound dressing.
