The account describes investigations into the variations of specific volume and viscosity of a typical high-performance epoxy resin during various time-temperature cycles. The work was undertaken primarily to provide additional background information relating to the nature and causes of “fibre kinking” which has been observed in laminates comprising epoxy-carbon composite. The investigation has quantified certain characteristics of the resin which are presumed to be major contributory factors in the occurrence of fibre kinking. It is concluded that a simple solution to the general problem cannot be identified, although some possibilities are discussed for individual cases.