Sealing multiwell plates

[0017]The multiwell plate 1, shown in FIGS. 1 to 4, comprises a plate 2 with an integral skirt 3, the plate mounting an array of individual thin walled wells 4. Lower edge 5 of skirt 3 is formed with an outwardly displaced rim 6, enabling the plates to be stacked one upon the other with the displaced rim fitting over the edge between plate 2 and skirt 3 of an underlying multiwell plate in the stack. The individual wells 4 are mounted in openings in the plate 2 with rims 7 extending above the surface of the plate 2. The plate has a chamfered corner region 8 and cut-outs 9 for indexing purposes. The design of multiwell plates is subject to a number of Standards, such as the SBS Standard, in order for multiwell plates from different manufacturers to be compatible with automatic plate handling apparatus, for example for performing the PCR (polymerase chain reaction) process; but persons skilled in this art will know that a number of variations are commonly encountered, including semi-skirt