Hi Stephan, welcome aboard.
Thanks for that info but I end up being more confused. Here are the names/data I came across (Glass-Study) - is this the same company?
1945 report on German Glass Industry
Name of Target Bayerische Spiegelglasfabriken Bechmann Kupfer A.G.
Address Fürth (Near Nürnberg), Kurgartenstrasse 47
Date of Visit 21st August, 1945
Products Polished plate glass
Decolourised Plate glass
(White opal and a semi-optical glass are said to have been made at one of the Czech Works of the concern.)
Present Position This target consisted of (1) the Head Office for several Works in this organisation, including one at Furth-im-Wald and three in Sudetenland and (2) a depot for carrying out bevelling and silvering of polished plate glass produced at Furth-im-Wald.
Name of Target Bayerische Spiegelglasfabriken
Address Furth-im-Wald, Bavaria.
Date of Visit 22nd August, 1945
Products Rough cast and polished plate glass
Decolourised plate glass (searchlights.)
1925 addressbuch
999. Bayer. Spiegel- u. Spiegelglasfabriken A.-G., vorm. W. Bechmann, vorm. Ed. Kupfer & Söhne, Blumenstraße 16. Fernsprech-Anschluß 628 und 572.
¾ weißes Spiegelglas, belegt und unbelegt, plan und facettiert, Spiegelrahmen und Flurgarderoben. Umbauten, Goldspiegel, Fensterglas. Rohglas für optische Zwecke. — Glasschleiferei, Beleganstalt. Dampf- und Wasserkraft, 2000 Polierbänke, 5 Oefen. 800 Arbeiter. (Gegr. 1847.)
Eigene Häuser, Berlin: Alexanderstraße 34. Hamburg Schönstraße 11. — Filialen in Berlin.
I checked some off-line sources too but only found the above company as a candidate - note the earlier established date in 1925 book.