A gasket must compress enough to seal but not so far that it extrudes, takes a permanent set, or holds the tool out of alignment. Uneven compression creates local leakage and can change the pressure applied to the sheet boundary.
Compression should be measured around the perimeter using the gasket supplier’s intended working range and the actual closure condition. Contact patterns, stop blocks, platen parallelism, gasket joints, and thermal expansion should be checked. A new gasket does not correct an uneven sealing surface.
Stops and closure settings should control compression mechanically rather than relying on operator feel or excessive force. Gasket material, hardness, section, and temperature resistance must match the process. Repeated replacement without correcting compression only resets the failure cycle.