Can anyway advise what the difference if any is of ASTM F36a and ASTM F36j. Can find anything anywhere. They appear to give out different results in gasket materials ?
ASTM F36 is a standardized method of testing for gasket materials: the intent is to define both compressibility and recovery. There are multiple testing sequences (A thru K); which one is chosen is based primarily on the material being tested. If you need more detail, go to the ASTM Standards store at