JBL did this back in the 70’s or maybe earlier with a coating called Aquaplas which I believe was like a silica based epoxy spray. Supposed to improve damping, making paper cones more rigid and probably, and historically proven to extend the cones life without the inherent dry rotting of old paper cones. I’ve got a pair of WX 4311s from the 70’s and the original woofer cones are still very firm and rigid. Also the treated accordion cloth surrounds were way ahead of their time.
Coated woofer - why?
An old (20+ years) speaker with multiple previous owners has a coated woofer - why would this mod be made? What are the implications for SQ? Speaker is a LS35A type with original KEF B110 woofer.