Electric Kiln Variations

[vangoghnights]

I'd like to know if I do my glaze testing in a small electric test kiln, I have an Aim 64/J that I have used for ceramic jewelry and to anneal glass beads, will I have the same results with the tested glazes when I fire larger pieces in a large electric kiln?    

 

 

 

 

Thanks for your help.

 

 

[Guest JBaymore]

Possibly not......... unless you understand the exact genesis of the effects in your glazes that you are getting from the larger kiln and take that into account.

 

One of the biggest factors in the development of MANY glazes is the impact of the cooling cycle on the development of precipitates (re-crystallization) forming in the cooling glass matrix. Slower cooling at certain temperatures facilitates this effect.

 

The cooling cycle of the smaller kiln will not match the cycle of the larger kiln due to a combination of it having less thermal mass, the higher exterior kiln surface area to internal volume ratio, possible lower wall insulation value, and the closer proximity of the refractory wall faces to the pieces themselves (and hence heat transfer to the cooling refractory walls).

 

Likely to get similar results, you will need to fire the test kiln down on a cycle that matches the cooling cycle ofthe larger kiln. This is easy with a computerized controller if you study the cooling of the larger kiln. Of course it you already fire the big kiln down to control the cooling cycle with that one...... (I recommend this highly) then you already have that cooling profile stored for reference.

 

best,

 

..............john

 

PS: Just thought of this...... the term "atmosphere" in the thread title might not be exactly accurate. If both kilns are electric and both are ventilated similarly..... likely the actual atmosphere (composition of the gasses in the kiln) will be quite similar.

[Marcia Selsor]

When moving to bigger electric kilns..be careful about the cooling. Make sure the peep holes are plugged up as it cools. Placing a kiln shelf above the load near the lid will slow down the cooling. If you have it, put some ceramic blanket on the lid. If you have computerized controls, you can program the cooling.

[saragdc]

When moving to bigger electric kilns..be careful about the cooling. Make sure the peep holes are plugged up as it cools. Placing a kiln shelf above the load near the lid will slow down the cooling. If you have it, put some ceramic blanket on the lid. If you have computerized controls, you can program the cooling.

 

 

 

Marcia -

 

I am in the final phase of setting up my studio and just fired my 30+ year old Crusader kiln for a ^6 glaze firing. This kiln is fire brick only on the exterior, and though I use the peep holes, when its on Hi you can still see the red of the interior between the lids and small holes inside the cage where the dials are located. It did not reach proper temperature, and it was very cold in the garage where the kiln is located. Do you recommend a ceramic blanket for the top? If so, any recommendations? I have heard mostly positive comments about using such a blanket but I thought I read that use of a blanket could heat the interior more intensely than it was intended for and could wear out the kiln faster.

 

If you use a blanket, does it remain completely on the outside of the kiln? I read some where to place it between lids?? I'm just trying to get advice before I make further mistakes. Thanks.

 

Sara

[Marcia Selsor]

Sara,

I have never had any problem using fiber blanket on top of the lid. I had two Crusaders more than 30 years ago.

Good kilns. If you are seeing red through the wall by the control panel, you could try stuffing some fiber in the cracks there too.

I leave the peeps unplugged until past 500 or so. even longer if I suspect a lot of chemical burnoff.

Marcia