Glass: electrical insulator?

[Cornbread]

so, glass is an insulator of electricity at room temperature. does it have any conductivity in a furnace in molten form?? if no one knows, ill grab my electrical tester to try it out. otherwise, i dont wanna stick my needles in molten glass.

just the curious bug in me

[Greymatter Glass]

yes.

Insulation is a factor of the temperature.

I believe it's a log function, not linear.

Some large furnaces actually submerge electrodes in the glass and use the glass as a conductive/resistive medium to heat up the surrounding glass.

Also, vitrification of nuclear waste uses large tungsten or SiC electrodes planted in the ground with a small starter wire to heat up the ground then turn it to glass and once there's glass it conducts.

This is also why many electric furnaces shut off power temporarily when you open the gathering port, so that if you hit the elements with a gather it will zap you (same as just a bare pipe)

[daveabr]

I've definitely heard of people getting shocked pulling glass out of crucible kilns

[stackerson]

hell yes....more than one shock this past weekend. from what i understand glass in an insulator at low temps but once hot and molten(not sure exactly what temp but definitly at 2300+) it is a conductor. the pots were raging this week at the shop and a few times we heard "aah, damn i just got shocked!!" lol nothing lethal but startling and kinda funny.

[daveabr]

i've not been shocked yet working out of a pot, i'll hope to keep that streak alive


the high temps that come with molten boro, probably make it even more probable

[Cornbread]

that's crazy awesome. thanks for the responses...glass is seriously just totally a legit medium. makes me want to just eat it up like candy!

[Abe Fleishman]

Stakerson What type of furnace are you useing?
Abe

[FredLight]

I've been shocked many times gathering out of crucible kilns.

That's usually how we know that the crucible cracked and glass is running out and touching the elements.

Not pleasant to get zapped when you're already trying to be careful.

[B-Rye-oNeR]

I got shocked by touching the coils in the kiln with a piece on a handle...It wasn't bad. (guess thats why it says dont touch coils with anything on the kiln)

[gn0me]

Funnily, a while ago at my other job (barista in Golden, Colorado) I was talking to a guy who'd just retired from running some part of the glass factory that Coors bottles come from. He said that they use an industrial oxygen concentrator facility and natural gas in order to get the glass molten, and once it begins melting they heat it up the rest of the way by zapping it with some huge electrodes submerged in the pool (literally olympic swimming pool sized vat of glass). Assorted chemicals are added (including some iron pyrite for the brown color) and the bottles are made, after which they're put on a conveyor belt style annealing kiln, still glowing. Once they traverse the kiln, they're fully annealed. How crazy is that?

[Din]

There is a technique of melting glass that relies on it's electroconductivity at high temperatures. I think it used graphite electrodes, I'll have to dig through Schole's again...

[Dragonharper]

Yes glass conducts very well when molten. The glass plants where I grew up used Natural Gas to get the glass melted then switched over to electric once it was molten. I believe the electrodes are tungsten, but don't quote me on that.

[Greymatter Glass]

You can use anything that wont melt at the glass temperatures and is compatible with the chemistry. Platinum, tungsten, graphite, and various silicates and carbides all come to mind...

[smolder holder]

Cool info, thanks guys

[stackerson]

hey abe...im not actually using them but the guys at the shop are. im down in humboldt working at tristan and scotts studio. things have been going off down here. pretty amazing/next level shit going on with all the furnaces/crucibles popping off! thanks to all who are making this a reality. could be the next level!!

[Cornbread]

yall are a wealth of information. thanks, for real.