[78-L] Approximating 78s age by physical characteristics

[David London]

>>> first laminated pressings
> Columbia and American were doing laminated pressings in maybe 1902 or 3.
>   The Columbia Marconi Velvet-Tone flexible plastic discs in 1907 were
> laminated. But Columbia was doing solid pressings as well until the
> introduction of the New Process in 1923.
>
>

I noticed you capitalised "New Process".  Was this the start of the 
modern laminated pressings?

Amongst all the modern (post WW2?) 78s I have, labels like Columbia, 
HMV, Parlophone, Philips are thicker and nicely laminated, but some 
still seem to be thin unlaminated - such as red Capitol label - the 
later Capitol went to purple and were laminated. (a side note - the red 
label Capitols all seem to have more surface noise as well) There's 
probably a whole long story here, and it may well be country/continent 
specific.

Is it possible to put an approximate date on when the "modern" laminated 
disc was first used mainstream?  Seems that nearly all later big band 
era and jazz records I have are laminated, except a few, such as red 
Columbia label from the US.  The impression I am forming is that the 
main changeover to laminated was happening about or just before WW2.  
The earliest I have noticed are perhaps some Regal-Zonophones from the 30's.