Sunday, April 19, 2009

Furnace work

I'm a "Furnace" glassblower. Why is that important? Because there are two types of glassblowers out there......furnace, and lampworkers. And we are very different. We work with different equipment, different materials (all glass is not created equal), and we make different objects.

I'm here to tell you about Furnace work. So, what better way to start than by showing you the Furnace.

It's about 6 feet tall, and 5 feet wide. And it runs 24 hours a day, operated by compressed air and natural gas. The idling temperature is 1950 degrees, and the working temperature is 2100 degrees. Yes, that's hot.

Why 24 hrs a day? Because glass has to be molten for us to work. It would take too long to heat glass to a molten state on an as needed basis.

(Open door)

Looks a little intimidating, doesn't it? To be honest, it is. Until you understand it. Then, it's just part of the process.

believe it or not, you can stand pretty close to it when it's open......just not for very long. Unless you want to get burned, or just singe some hair off your arms.

Inside the furnace sits a free standing crucible.......a ceramic bowl. It's made to withstand high temperature, and it is filled with approximately 150 lbs of molten, clear glass.

Here, the furnace has been turned off, and the door removed, and is a nice photo of the inside of the furnace.

A question we are frequently asked is "how do you get the glass in there?"
A: We use a powder/pellet, silica based product (that we buy, it's called 'batch'), and we use a very long shovel. I'm serious. And scoop the batch into the furnace while it's hot. We then spike the furnace temperature to 2350 degrees. Over a 16 hr cycle, the batch melts to molten glass. Viola.
By now, I'm certain you are now wondering how to get the glass out of the furnace. Well, that is a story for another day.

But, I'll give you a hint, it involves these pipes. Stay tuned.

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