From: Tracy Popp <[log in to unmask]>
> Ah, very interesting about the Diamond Discs... Having just recently
> handled one myself I thought they were just a very thick shellac.
> Good to know about the wooden core! I'm assuming these discs are
> then subject to the same types of preservation concerns as other
> laminates - swelling/contraction of the core, laminate peeling, etc.?
They vary in construction, and none were shellac. The early ones did
have a wood flour core which was subject to swelling and delamination,
especially the ones which had celluloid transfer surfaces. They then
started to use condensite surfaces which were brushed on as a liquid.
In the early 20s the cores became clay based and were much more stable.
This has been detailed in a number of books by Ron Dethlefson and George
Mike Biel [log in to unmask]