Steel bells

[George Dawson]

Perhaps someone can help me with an American enquiry I've just received.

The steel bell in question has clapper springs to lift the clapper off the
bell after striking. At the end where the clapper shaft hits the spring
there was some protective material so that its not metal hitting metal (just
as handbell springs have felt). Does anyone know what was originally used?

All the ones I've seem had nothing.

Thanks.
George