UNFILLED CARBON U003
This grade of carbon contains carbon-graphite and nothing else.
Filled carbons contain inorganics that will be sensitive to some chemicals and temperature extremes.
With the exception of cryogenic service, unfilled carbons should be your first choice if you are going to use any grade of carbon for a seal face.
Be aware that oxidizers, halogens and several other chemicals can attack all forms of carbon .
Please see: carbon face manufacturing C010