Ceramic Gas kiln

[Havi]

I have a ceramicist friend, who owns a ceramic kiln working on gas.
She says that the hot air comes from the bottom of the kiln and spreads around up to the top.
I understand that like other cermic kilns it is cylindrical.

Do you think it will work for glass fusing???
Or is it the same as electric ceramic kilns that one has to have a slower firing - compared to a regular glass kiln?


I'd appreciate you imput,
Many thanks,


Havi

[Tom Fuhrman]

I've seen several older gas fired glass decorating kilns. The gas can work, it just takes a lot of experimentation until you understand the intricacies of your equipment. Many of the larger glass decorators used gas kilns for many years and a lot of the large bent glass companies used them as well. I've seen some that were 20' in dia. and on a turning axis and they had several hundred slumping molds on them. They slumped the 12"X12" light fixture bedroom pieces in these for many years and virtually no kiln, just a lot of heat and they could do it in less than 1/2 hour from start to putting them in the carton. Philadelphia Glass Bending used to run one of these as well as others.
Lots of things are possible if you want to spend the time and effort to get them to work.

[Stephen Richard]

There is no reason why glass would not fire in a gas fired kiln. I have found that I can fire at least twice as fast in a gas fired kiln than an electric one. The heat in a gas ceramic kiln is coming from the top and so acts more like a top fired glass kiln. If you fire fast, you will not have a lot of brick heating up, so the cooling will be easier too. A good solution.

[Havi]

Thanks, Tom and Steve,
I understand that in my friend's kiln the heat comes from the bottom, and then spreads in the kiln.
So this is something different than heat coming from the top.


I just do not know what to tell this friend, and I do not want to misguide her.,


many thanks,

Havi

[Stephen Richard]

Havi,
The heat originates at the bottom at the burners. It the flow up to the top of the kiln through baffles. So the radiant heat is effectively from the top.

[Don Burt]

Havi,
The heat originates at the bottom at the burners. It the flow up to the top of the kiln through baffles. So the radiant heat is effectively from the top.

That seems strange to me. If I look at heat flow diagrams of both updraft and downdraft gas pottery kilns, with flame origin on the bottom, they show convection currents surrounding the ware in the kiln and heating evenly on all sides including bottom. They don't indicate that radiant heat from the top is significant. Convection is the primary source of heat distribution.

[Morganica]

I've cast mid-sized pieces in gas kilns, but the schedules were very loosy-goosy, i.e., get to a temperature very slowly and hold it there for hours to equalize, move to the next temperature and hold it there for hours, etc.

I would think the ability to fire glass in a gas kiln would depend on the precision of the controller (and if there is a controller). If it can hold to +/- 5 degrees, i.e., a 10-degree spread, it would work like any electric glass kiln. When I checked a few years ago, that was still the province of pretty expensive kilns, and most of the potters I knew didn't want to spend that much money.

[Havi]

Thank you all.

This discussion leads me to the conclusion, that I would recomend to that ceramicist not to use her gas kiln for glass. Especially her being a beginner in glass. I am afraid it will be too complicated for her.
I remeber having read discussions here, dealing with the ways to use electric ceramic kiln, but not gas kiln. It seems to me now, that working with a gas kiln gets things even more complicated.

I will not take responsibility to guide someone with something I myself do not know how to use.

Thank you very much, as always,

YOU ARE THE BEST!

Havi