Pot Cracked

Here is an image of molten hot glass oozing out onto the ground from a 2200 degree furnace. The crucible inside the furnace holds 300 pounds of clear molten glass and gets a lot of use from students when its in service. It’s totally out of service now. There was a power outage several months ago and the furnace dropped to a lower than comfortable temperature for the crucible filled with glass, and caused it to crack. It didn’t start as a big crack - but once its there it propagates with each charge of batch. The furnace goes up above working temperature to melt the cold raw glass batch and then is cooled by the batch making the crack worse over time. We had been charging the furnace and the glass level wasn’t getting any higher. We saw the crack but were in denial. It just didn’t ring a bell that all that batch we were charging was leaking into the main furnace chamber and filling up with molten glass. The problem was only going to get worse. So it was time to investigate the issue by opening the “dog house” and thats when the cold shock of reality bared its teeth.