It's been on my mind since I started my collection about 8 years ago
but for some reason I've never asked.
I'm musing here - I guess contemporary/20th century red is maybe either gold ruby (e.g Whitefriars), copper ruby, or selenium?
There seems to be some mid century Scandinavian mold blown glass in red. I have a couple- think Aseda - and think Riihimaaki used a red - I've kept them because I quite like the shapes but can't afford the real Scandinavian mid century avant garde shapes so never made a collection. I don't think it's gold ruby but I suppose maybe copper ruby.
I think some Scandinavian makers used selenium and also I think there is some Russian and Ukrainian glass which used selenium?
So I'm assuming red is difficult to work with ( I think ?) but it's really strange none are in the Sklo Union sets. Is it difficult to produce consistent colour and also expensive maybe?