Why do glassblowers have to rebuild the furnace?

Did you know we have to decommission and recommission the furnace every few years?

When in commission, our furnace runs every hour of every day, staying between 1125ºC and 1280ºC. It is built out of high temp ceramic castable cement and takes around six days to reach optimal temperature. 

The raw materials of glass (called batch) is sand mixed with soda ash and calcium carbonate, amongst other ingredients. The night before blowing the batch is loaded 3 – 4 times into the furnace and melted down. The temp then goes up to 1280ºC  to melt and refine the glass, then dropped back to 1120ºC working temp.

When the raw material melts in the furnace, it takes on an acidic quality. The acidity eats away at the furnace, so every few years, we have to rebuild it.

Take a look at our month-long Autumn 2023 rebuild, in 20 seconds: