Or perhaps Hurdal didn't make lead glass but Nøstetangen did? If that were true that might place your glass with Hurdal?
That said, in the research 'Chandeliers from the Nøstetangen Glassworks: Style, Craftsmanship, and Chemical Characteristics
Anne Bjørke and Isabelle Biron' in 'Journal of Glass Studies
Vol. 50 (2008), pp. 143-157 (15 pages)
Published by: Corning Museum of Glass' it mentions that production of lead glass probably continued at Hurdal.
Perhaps both glassworks produced lead and non lead glass? The way I read that research (page 156 of above) seems to indicate Nøstetangen made both lead and non lead glass.
My flaske is very big, like a gin bottle, but doesn't feel heavy so I assumed not lead glass. However I've no idea how to measure the specifics to identify lead glass.
Just to add dates for future searches on the board:
According to the information in 'Chandeliers from the Nøstetangen Glassworks: Style, Craftsmanship, and Chemical Characteristics
Anne Bjørke and Isabelle Biron' the Nøstetangen glassworks was established in 1741 and closed in 1777.
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