Lighting up the furnace is always an exciting time in the studio! Most people don't know that it takes a week to warm up our furnace from lighting it to being able to blow glass. It is a methodical process to ensure a long life for the furnace. This keeps us happy as replacing the furnace is a very costly endeavour that is inevitable at some point, but if you can get an extra year of use out of it, you can save quite a bit of money!
The Furnace; empty and cold!
Once some general maintenance is done on the furnace and it's components, it is ready to light up. The electrical components are tested and checked for proper operation. The crucible (the big ceramic pot in the furnace) is checked and cracks are repaired. It is much more difficult to make repairs on the furnace once it's operating, so it's best to work on it when it's shut down. The operation of the studio relies on the furnace, and if it shuts down unexpectedly it can cause many problems, upsetting plans and costing time and money!
Once everything is ready, we light it up!
The initial light up is done with all the doors open, and the flame on as low as it can go. After a day like this the main door is closed half way for another 24 hours. Then the door is closed all the way, and again, after a day we turn up the flame to its regular operating settings. 24 to 36 hours after this we can start "charging" or loading the furnace with glass. The glass will take another 36 hours to melt down and fine out (get rid of small bubbles).
Usually if all goes well we can blow glass a week after lighting up!
Looking into the furnace at operating temperature.
Once up to an operating temperature of 1175 degrees Celsius (2150 degrees fahrenheit) the furnace will remain at that temperature for weeks and/or months on end. Since it is constantly running it needs several safety systems to ensure the safe operation of the furnace, especially when it is unattended. A flame sensor located in the burner tip that "looks" into the firing chamber sends information back to the controller. If, for some reason the flame is out, the controller will automatically shut off the propane supply. The same will happen if there is a power outage which would turn off the exhaust and the forced air for the furnace. Even if we break a belt on the exhaust system, the furnace will be shut off. So it is in our best interest to have all the equipment in the shop running at it's best while we are working. Having a smooth running shop enables us to focus on our work, which is what we enjoy, and enables us to be as productive as possible!