Grapho -Glass
"Hard and crusty after heating up. Prior gasket was still soft and pliable after 8 years."

Rutland Grapho-Glas is used as gaskets on the doors of wood burning stoves, coal stoves, and fireplace insert stoves. It's graphite impregnated to resist abrasion. Grapho-Glas is used as original equipment by major stove manufacturers, as well a replacement for worn out gaskets. Available in many sizes and lengths.
Additional Information:
WARNING: This product can expose you to chemicals including Carbon Black and Crystalline Silica, which are known to the State of California to cause cancer. For more information go to http://www.P65Warnings.ca.gov.