[78-L] glass record mystery

[Malcolm]

Only thing I can think of is an odd lacquer mixture with something in it 
that wouldn't pass light.
Why is a whole other question.
I have found that, on glass discs in my collection made in the 
Netherlands during WW2 at about the same time as yours are, lacquer 
flaking is even more prevalent than on aluminum based disks. I've often 
wondered why the glass wasn't buffed opaque rather than transparent to 
allow better adhesion of the lacquer. Nothing gross, just enough 
scuffing to allow better sticking.
I don't think I have ever seen any kind of glass that light wouldn't 
through, even sunlight.
Malcolm

*******

On 9/4/2016 7:02 PM, Joe Salerno wrote:
> Recently I acquired a number of glass based records. Or I think they are
> glass. Some say they are glass. They are flat like glass. They weigh
> like glass, sound like glass when you tap them lightly with your
> fingernail, and looking at the edge of the center hole, I don't see
> anything that looks shiny like aluminum. Dates are 1944, which would be
> the right time frame for glass.
>
> But when I attempt to shine a bright flashlight or a red laser thru
> them, they are opaque, even in a very dark room at night.
>
> Is there some reason why a glass based disc would not pass light?