Averting kiln disasters

[Cheryl Quintana]

Hi All:

When firing my kiln, I will wait until I have enough pieces to jam the kiln full.  But the more that I thought about things, maybe this isn't the best practice.  For example, if one piece blew up in the kiln, this could have the potential of ruining an entire shelf worth of sculptures. 

Just curious what others do.  Do you wait for a full kiln or selectively fire based on the pieces?

Thanks in advance for your input!

Cheers!

[Russ]

Well for economic reasons I would think most potters fire a full kiln. I usually fire anywhere between 300 to 500 pieces in my kiln and if  fired correctly there's usually no concern about exploding pieces.

[yappystudent]

Same question but I'm wondering about efficiency of firing bisqueware stacked together and the possibility of outer pieces shrinking to break or trap one's set inside. I assume as long as they are the same clay this won't happen? 

Also the subject of heat/air movement around the shelves and pieces, is it really going to be a problem with just bisqueware in an electric kiln? My kiln's manual seems to say one thing, observations of how other ceramicists do things is another. 

[Mark C.]

If your work is dry then blowing up is no issue-I always fill kiln and fire it depending on how dry it is. 

Learning to gauge dryness is a skill for sure but one needs to learn for ceramics to go smooth-that is until you blow up stuff.

[neilestrick]

Pack it full! If you're worried about dryness, run a preheat.

[hitchmss]

I pack my oval tight as I can when I bisque. I normally put a hold of 5-15 min (depending on tightness of pack) to ensure that the core has reached same temp. If you have wetter pots, dont put them towards the center &/or bottom where it takes longer for heat to reach.

Learn how to stack pots that the weight isnt being supported on the rims; pass the weight through the bottom of the pots, and consequently to bottom of kiln. Too much weight will crack rims. Also, dont pack it that pots cant move at all. As they expand, if they dont have a little room they will break themselves. Tumble stacking is what I do and there are some tricks to it. Better to fire pots than furniture.

In my glaze loads I leave no more than 1/4" in between pots when possible. I like to fill the kiln as tightly as possible with the idea that the radiant heat among all the work will help even out small zones of cooler temps.

[Mark C.]

 

(In my glaze loads I leave no more than 1/4" in between pots when possible. I like to fill the kiln as tightly as possible with the idea that the radiant heat among all the work will help even out small zones of cooler temps.)

Good plan above for sure. I pack as tight as a thin piece of paper between pots as they shrink away from each other. The let them breath is for mammals not pots in a reduction atmosphere  or an electric .The salt kiln is a bit different as you want vapes around the wares but in electrics and gas reduction tight is better.

This thread is about averting kiln disasters and I can say they you will have one or two  or three over time for sure its just a matter of time. Thats what ceramics is -learning and disasters are all part of the learning deal.

[tomhumf]

On 5/4/2018 at 1:08 AM, yappystudent said:

Same question but I'm wondering about efficiency of firing bisqueware stacked together and the possibility of outer pieces shrinking to break or trap one's set inside. I assume as long as they are the same clay this won't happen? 

Also the subject of heat/air movement around the shelves and pieces, is it really going to be a problem with just bisqueware in an electric kiln? My kiln's manual seems to say one thing, observations of how other ceramicists do things is another. 

If you have a set of bowls the same size I wouldn't stack them as they are else they could crack. You can add sand between bowls, depending on their design, so the walls aren't touching and the weight is loaded onto the feet. 

This kind of dense stacking might prevent some of the inner bowls from reaching temp though depending on your firing cycle. 

I've suffered from some pinholing problems after doing this but not certain they were related. 

[Mark C.]

(This kind of dense stacking might prevent some of the inner bowls from reaching temp though depending on your firing cycle)

most likely from Stoneware at cone ^6  I'm thinking 

No issues with porcelain bodies as to the dense stack and pin holing from organic burn outs

[Pres]

I tumble stack a lot of times, as when doing a load of mugs, or a mixed load of mugs and small jars etc. However, when it comes to smaller bowls I box them rim to rim, foot to foot. I usually put a piece in each box, but sometimes not. Larger bowls I do the same, putting them in the bottom, and then shelving over top. As to patens(communion plates) I never have had luck trying to stack them other than on a shelf for support. I do box these also, with shelves to have 2-3 plates to a shelf Next kiln should be a little bigger around, as I have to stagger the 1/2 shelves to get the plates in due to overlapping diameters, but it is doable.

 

best,

Pres

[neilestrick]

Bowls can be stacked inside each other as long as the weight is carried at the bottom. That is, the foot of the bowl must sit all the way down onto the bottom of the bowl below it. No weight or stress on the rims. I usually stack bowls and plates in stacks of 5 or 6 in bisque.

[Denice]

You were talking about sculptures,  I do a lot of hand built work and sculptures and I would candle them overnight before I started firing them in the morning.  Denice