A crucible is a ceramic pot that holds molten glass in a furnace. Over time, crucibles degrade due to extreme heat and chemical reactions with the glass, and eventually, they must be replaced. Not surprisingly, this piece of equipment is essential to our Hot Shop operations, and it is usually repaired on a regular maintenance schedule.
Recently, ours sprung a hole and unexpectedly put us on an emergency timeline for repair! A crucible swap is a lengthy process that can take up to nine full days in total, so being able to plan for it is the ideal situation. As life often does, we were thrown a curveball — and our incredible Studio & Gallery teams rose to the challenge!
The Surprise — When Plans Melt Down
We noticed suspicious symptoms that suggested our crucible (pictured above) might have sprung a hole. Once confirmed, we were full steam ahead with moving towards an immediate crucible swap (replacement). Not in January as planned - but immediately!
Did you know cooling off a 2100 degree Fahrenheit furnace can take up to three full days?
Our studio team started the replacement process by scraping all of the molten glass out of the chute. They also ladled out all of the molten glass that was still remaining in the crucible. And if you’re curious, we do recycle what was ladled out of the molten glass!
Then, a three day cool-down of our Hot Shop furnace began. Meanwhile, our gallery team made phone calls to our valued customers to inform them of the need to reschedule their Hot Shop classes.
Once our furnace cooled down, the next step was to remove any scrap glass that might be remaining. The bucket pictured to the left is a bucket of scrap glass that came our of the furnace.
A pneumatic chisel was used to break up a 1”-thick layer of glass that was left after scraping the majority of the glass down.
In the context of replacing a crucible in a glass furnace, a pneumatic chisel is used to break apart the old material that has solidified around the pot. This material becomes brittle because it has not gone through the annealing process.
Pictured above is our studio manager, Tim, using the pneumatic chisel in our Hot Shop.
After using the pneumatic chisel to break up the residual material left by the old crucible, our studio team switched to a hammer and chisel for the delicate work. The final bits of material were carefully chipped away by hand near the ceramic walls of the furnace — a slow, precise process to avoid damaging any of the surrounding areas, if at all possible.
