The offending compound was asbestos, I believe.
I think a better way of putting it is "The stuff that made the original seal design work correctly was Asbestos."
Utter lunacy about Asbestos going on at that time. It was a result of trying to be politically correct that they insisted on removing Asbestos from the seals.
Asbestos seals would have prevented the disaster.
“The offending compound was asbestos, I believe.”
The lack of asbestos in the sealing putty has been blamed by engineers