I think one of the keys to this discussion is about who made the caps.  The dates
usually quoted are (I think) for the Crown Cork & Seal Company.  Once their patent
ran out, others were free to join in the sales competition.  Other companies may have
continued to use composition cork liners long after the big #1 disdained such things.

Bill

> I have a box of Jointite bottle caps here at my house that I think
> dates from the 1950s. They are all cork. This old and brittle box was
> made for home brew.
>
> Ron May
> Legacy 106, Inc.
>

Bill Lockhart
New Mexico State University
Alamogordo, NM
(505) 439-3732