The late 1950s saw the introduction of Teflon as a valve material for seals and closure members.
This vintage Dupont ad touts the exemplary properties of Teflon as a membrane material for diaphragm valves. You might call it either the “Great Teflon War” or “The Battle of Massachusetts”
No matter how it’s labeled, however, the victory prize was substantial: rights to the patent for the first functional bidirectional elastomer-seated ball valve.