In the 1835 a married couple František and Antonie Kavalírovi bought a mill Na Kácku, in those days it was about 2 km up the river from the town Sázava. Two years later they built near the mill glassworks of Svatý Prokop, around which was later founded a self sufficient glassworking settlement similar to those forest huts, which is kept in the same state till the present day, except the first one.
In 1882 a son of a couple Kavalírovy Josef has built in the glassworking settlement Na Kácku second glassworks František, first with only forest ladle furnace which was heated using wood. Melting glass using this furnace was problematic and the conservative Josef was in the end persuaded by his young son Vladimir, who was in german glassworks and so in 1883, he built near the glassworks František a generator for gasification of wood and the original furnace was changed for the furnace “gázovna”, which is a modern regenerative gas heated furnace made after Siemens’s invention.
A modern furnace increased the quality of melted laboratory glass. The oldest glass KS (Kavalied-Sázava) was replaced by glass with business name UNEXCELLED and INFUSIBLE. The main disadvantage of the original furnace was the fact, that thanks to the direct heating system the glass became very difficult to purify, so the remaining bubbles were received by foreign customers as a characteristic symbol and a proof of the quality of fire resistance. When after 1884 glassworks František successfully raised the melting temperature and they were able to melt glass without bubbles, this higher quality caused for a longer period of time a mistrust of customers, who wanted wanted the former glass with bubbles.
A lifespan of forest glassworks was usually around 30 to 40 years. Glassworking furnace consumed after that time fuel from the entire area in the reach of economical transport.So the only remaining option was to abandon glassworks, and so the glassworks and the glassworking settlement went rack and ruin, they perished and the only thing that reminded of them was only a local name: V Hutích (In Glassworks), Stará Huť (The Old Glassworks), Nové Hutě (New Glassworks), Huťský les (The Glasswork forest), Hutisko etc. Fortunately, this was not the case for glassworks František. It had always plenty of lumber thanks to its economical transport on the river from the Sternberg manor.
The glassworks František build in the style of the original forest glassworks is kept in its original state, the same goes for the glassworking settlement Na Kácku, which is its part. Five years ago the most neglected city quarter of Sázava has changed thanks to the project of the city “Revitalization of the brownfield of the former glassworking settlement Na Kácku” supported by ROP, finished in October 2009 and the project “Glass Art Centre, Glassworks František in Sázava” into a cultivated authentic place which is documentating czech glassworking tradition.