Sklo Union is in fact not very correct term. After WWII in 1945 were all glass factories nationalized (only 2 Skrdlovice and Rudihut survived but only 3 years more) and 16 so called national corporation has been created (n.p. = national corporation). After communistic putsch in 1948 were national corporations again re-organized and several corporations splited some other united. The most important issue is that on 1949 was established Skloexport (Glassexport) - the company that exclusively exported Czechoslovakian glass produced in all national corporations with exception of Jablonecke sklárny exported through Jablonex)
Than next re-organization came in 1958 other next in 1965 when the Sklo Union o.p was firstly created - Sklo Union covered 14 directly managed factories for flat glass production and container glass. Before 1965 we cannot talk about "Sklo Union" because this phenomenon did not exist. Another re-organization has appeared in 1971 and the last in 1988. The structure of national and state corporation is quite difficult and cannot be described within few lines.
Marcus correctly identified 4 main factories that worked since 1945 under the common management and produced domestic glass (Rudolfova hut, Hermanova Hut, Libochovice, Rosice + part time Nemsova) and he has covered under the Sklo Union label, what sounds for Czechs a bit strange.
Sklo Union name for us means mainly flat glass, bottles and glass insulations production, also the football team, for older guys.
But I can accept this designation, for foreigners it is much easier. Who cares that the most of Vizner’s “Sklo Union“ pressed pieces were produced in concern named VHJ Obalové a lisované sklo.
Speaking about the glass we collect – art and domestic glass – in Czechoslovakia were two another big producers of pressed glass – Jablonecké sklo n.p. and Sklárny Bohemia Poděbrady.
I never seen the vase displayed at pictures, but the overlay technique focus me just to Bohemia Podebrady n.p.