Thanks, to both of you.
Now, the reason for the question is that when the Beraneks set up production, some, though not all was schaumglas, and I have been trying to link this, to Beranek's known work places, prior to Skrdlovice. I have an idea, based on labels for glass produced for Drustevbni Prace, that Emanuel at least, probably learnt the technique at S.Reich's at Krasno.
This would indicate at sometime in the period 1938-41. I have seen it written somewhere that Beranek's early work "was poor quality, as it was full of bubbles", tho right now cannot remember the source.
Your article from Orville Burg, is interesting in that is uses the term schaumglas for the three-layered vase, but foam-glass (the English translation, according to the ICG's Dictionary of Glass-making) for the bubbly glass applied. This rather suggests that the term can be applied to a vase wihich includes glass of this type, as well as to items made solely of schaumglas.