I have just had a chat with the materials scientist who developed the compressed graphite material, who just happens to be my next door neighbour. She said that it was developed for head gaskets for big diesel American trucks so can take high temperature and pressure. They should be fitted to clean metal without any form of gasket goo. It compresses when first compressed but not afterwards so it is not necessary to re-torque. Her great difficulty when doing the testing was to separate the surfaces after compression! I have used them for several years and found they work very well. I torque down to 60lb/ft or 80 Nm.
