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Mark C.

Tumble stacking the bisque-electrics

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Mark C.    1,805

Get the most use of space from your electric kiln. This maybe a new idea for you or you already do this and its old hat.

 

As many here use electric kilns and may not be aware of what is possible as far as stacking your work-whether its sculpture or pots.

 

You do not have to place them with space between or even on the feet- pack it tight. One can fill every nook by placing pottery in any direction.

 

I only bisque fire in my electrics and rarely at best these days,as the gas kilns are larger and cheaper for me to run. That said when I need a little last minute work I’ll fire one up in the evening as that’s the best electric rate with my (TOU) Time Of Use electric meter. If you fire your electric kiln a lot you may want to check with your utility on this meter as you are charged different rates at peak times and lesser rates off peak. The meter does have a daily charge to own. Ours paid for its self in a few months as we try to only use power on things like cloths washing-dryers (motors) and electric kiln use off-peak hours.

 

I use kiln shelves as usual during the loading but stackpots in all directions per layer to get the most use of space. Whatever you can squeeze in-filling the insides of pots, pots on the edge or upside down or sideways-no matter

 

The key thing is that the work is bone dry. Now this may not work on a sculpture you have worked on for 3 months and is still wet in the center.

 

So the next bisque fire try to fill all the space withtumble stacking in mind.

This kiln is a skutt 1227 .

 

Mark

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neilestrick    1,381

Beautiful load! My students always freak if I put something on its side. You can do that?!? Won't it break?!? Love it.

 

Whatever you do, try to keep things at least an inch away from the elements, as being too close can shorten element life.

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Lucille Oka    16

That is an impressive stacking and just like Neils' students it frightens me. Do you plan this stacking before you load? It looks a bit haphazard. The clay you are using must be stoneware. It is a work horse of a body, but I am not so sure this stacking is good for porcelain. And it is not the kind of thing I would be willing to test, not with thin porcelain vessels, earthenware maybe.

 

It is also necessary to measure the top shelf for clearances. A few vessels in your photo look as if they will touch the lid when it is closed.

One thing you mentioned about the sculptures not being dry inside, I would suggest to sculptors to use cardboard cylinders or cones for armatures for they are easily removed from sculptures as they get wet from the clay. They provide a hollow core in the piece. They can then prop the piece on small blocks leaving the core unobstructed allowing for more even drying.

 

 

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Mark C.    1,805

That is an impressive stacking and just like Neils's students it frightens me. Do you plan this stacking before you load? It looks a bit haphazard. The clay you are using must be stoneware. It is a work horse of a body, but I am not so sure this stacking is good for porcelain. And it is not the kind of thing I would be willing to test, not with thin porcelain vessels, earthenware maybe.

 

It is also necessary to measure the top shelf for clearances. A few vessels in your photo look as if they will touch the lid when it is closed.

One thing you mentioned about the sculptures not being dry inside, I would suggest to sculptors to use cardboard cylinders or cones for armatures for they are easily removed from sculptures as they get wet from the clay. They provide a hollow core in the piece. They can then prop the piece on small blocks leaving the core unobstructed allowing for more even drying.

 

 

 

L. O.

Its all porcelain -Laguna's Dave's porcelain-and its very haphazard. I have been doing this for 35+ years with no losses for this stacking yet( yes I have blown up work over my career). As far as being close to the lid-I just sight across the top. If its to high move some stuff around till it just clears. Close is fine.

My point here is that one can get more use of kiln space-most pottery classes/schools never teach the limits of what is possible. After doing this so long I can say if its bone dry and as Neilestrick said not paper thin then go for it. Folks can push the limits and find things work or not. I'll share what I have learned as I always push the edge you have to to know what's doable and what's not. Throw sun dry trim sun dry bisque same day-yes you can do that to with simple forms as well.

I never plan to much before loading as its such a weekly thing its second nature as I'm sure it is for you. Yes damp forms go lower in kiln dry on top but thats just what one does. I'm a production potter so filling the space is key.

I mentioned the wet forms as this will not work for them or all work for all folks-but for dry items go for it.

Slip cast work can take the most push as its all even wall thickness. All these pots are wheel thrown as I do not slip anything anymore.

 

Mark

 

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Pres    896

That is an impressive stacking and just like Neils's students it frightens me. Do you plan this stacking before you load? It looks a bit haphazard. The clay you are using must be stoneware. It is a work horse of a body, but I am not so sure this stacking is good for porcelain. And it is not the kind of thing I would be willing to test, not with thin porcelain vessels, earthenware maybe.

 

It is also necessary to measure the top shelf for clearances. A few vessels in your photo look as if they will touch the lid when it is closed.

One thing you mentioned about the sculptures not being dry inside, I would suggest to sculptors to use cardboard cylinders or cones for armatures for they are easily removed from sculptures as they get wet from the clay. They provide a hollow core in the piece. They can then prop the piece on small blocks leaving the core unobstructed allowing for more even drying.

 

 

 

L. O.

Its all porcelain -Laguna's Dave's porcelain-and its very haphazard. I have been doing this for 35+ years with no losses for this stacking yet( yes I have blown up work over my career). As far as being close to the lid-I just sight across the top. If its to high move some stuff around till it just clears. Close is fine.

My point here is that one can get more use of kiln space-most pottery classes/schools never teach the limits of what is possible. After doing this so long I can say if its bone dry and as Neilestrick said not paper thin then go for it. Folks can push the limits and find things work or not. I'll share what I have learned as I always push the edge you have to to know what's doable and what's not. Throw sun dry trim sun dry bisque same day-yes you can do that to with simple forms as well.

I never plan to much before loading as its such a weekly thing its second nature as I'm sure it is for you. Yes damp forms go lower in kiln dry on top but thats just what one does. I'm a production potter so filling the space is key.

I mentioned the wet forms as this will not work for them or all work for all folks-but for dry items go for it.

Slip cast work can take the most push as its all even wall thickness. All these pots are wheel thrown as I do not slip anything anymore.

 

Mark

 

 

 

I too have been tumble stacking kilns with student pots since the 70's. I usually put some of the larger pieces in the bottom upside down, packed pots around them, and continued on up to the top. I liked to especially box bowls and pot together with others inside of them, I usually tried to distribute weight on several pot from layer to layer so that nothing had too much weight on it alone. Pots on their side had not problems as they were ^06 bisque for ^6 clay. Over the years I never lost a pot due to my kiln loading methods. I found that the very infrequent blow up in a tumble pack actually did less damage than in a less packed kiln because the pieces didn't go far.

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Lucille Oka    16

Okay you brave courageous guys. I must say that it is still frightening to me. I am fearful that handles and 'thingamajigs' would be lost so I must go upright or upside down but I can't do sideways. Also I plan firings differently based on the sizes of the vessels including handles, lids, lugs, knobs and etc., (thingamajigs). And yes I too try to get the vessels as thin as possible. If one day I must do it I may give it a try maybe.

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At my school studio we half-way tumble stack student pots. There are some shelves in there, and pots usually lie upside down or right side up, but we stack 'em up high!

As it is student work, there is always a huge variation in wall thickness, size and shape , so sometimes it is much more neat like a glaze fire; but not often.

 

Also, i recently bisque ffired a bunch of "thingamiajigs" in my woodstove; i tumble stacked them like mark; but my space was only one cubic foot or something ridiculous. I tried to push the limits on heat/time with 3 hour schedule cool-hot-cool (enough to lift with gloves) with only two pieces lost of a total of 10 or so fires.

 

You never know until you try!!!!

 

Mark,

 

That is amazing! have you every put witness cones in the middle of the load to see if there is any significant difference in temp? (not that it matter a whole lot for a bisque)

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Marcia Selsor    1,301

It used to frighten my students too by tumble stacking. So many people tumble stack all over the world. It is really a simple way to fire and less mass than shelves.

Nice load Mark.

Here is an example of the top chamber of a three story kiln in Agost , Spain. These are water coolers, wood-fired, no glaze.

They fire 11,000 per load in these huge kilns.. The second photo is the middle chamber. The pots for the bottom Chamber are carried across the plank over the fire pit in the foreground and a bag wall is built between the pots and the fire. This [photo is after the firing and during the unloading after cooling for 5 days or more. The ash in the pit was still warm.

Marcia

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Natania    6

I definitely believe in packing a kiln tightly and I stack things sometimes 2 and three "stories" high. However, I have noticed that with my cone 6 B-Mix sometimes a piece or two warps when put at an odd angle, even in a bisque. Is that because it is too thin? I tend to err on the too-thin and not the too-thick side sometimes. Otherwise, I am a tumble stack enthusiast and do it with pieces made from other, more robust brown clay...

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bigDave    4

 

 

 

So the next bisque fire try to fill all the space withtumble stacking in mind.

 

 

so there is no shelf in the kiln, just stack upon each other

 

mark can you give some guidelines

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Lucille Oka    16

I remembered a horror story of an 'instructor', who was not, shall we say, well versed in the art of firing ceramics, he did know how to kiln wash the shelves however. He once did a stacking of ware in this manner, however he was not aware of one thing you cannot stack this way with glazed ware. He opened the kiln to find one huge paper weight. But you've got to give him credit for sharing his huge mistake which occurred in front of all of his students whose work became part of a 'true class project'.

I am going to try this stacking method tonight with three tall greenware, porcelain vessels. Now all of you brave pottery stackers better be right. If it doesn't come out right "I'm going to blame some of the people in this room and this I cannot forgive. But that aside, I swear on the souls of my grandchildren that I will not be the one to break the peace we have made here tonight".

 

Not really, I recently watched 'The Godfather'. I will relay the results good or bad after cool down.

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Denice    243

Lucille I didn't know you had such a great sense of humor, good luck with your stack firing. I have stack fired before and didn't have any problems, I plan to have a stack firing in a couple of weeks myself. Denice

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Mark C.    1,805

Here are some details for those who asked.

No witness cones for bisque-just a cone in the sitter-I do not care if the temps are off some.

As far as shelves this kiln load had about 3-4 layers of shelve but pots are stacked tight between layers-the top one is shown.

You fill the kiln to the top and eyeball to make sure no pots stick above top level.

Every load is different and some require moving some forms till you get the most in.Over time you get a feel for what fits best.

While we are talking about this one develops over the years a feel for what size stilts to use with out measuring and what fits best form wise per given space. I never have to measure how tall a piece is-You just know-this skill takes many years to get dialed but it does come with practice.

If your forms are warping in a bisque they are either still wet or real thin-super thin forms take more care in all regards.Back in my school days a friend called them potato chips when he saw my work-I gave that up long ago for stronger daily use functional forms which are thicker.

Mark

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Pres    896

Here are some details for those who asked.

No witness cones for bisque-just a cone in the sitter-I do not care if the temps are off some.

As far as shelves this kiln load had about 3-4 layers of shelve but pots are stacked tight between layers-the top one is shown.

You fill the kiln to the top and eyeball to make sure no pots stick above top level.

Every load is different and some require moving some forms till you get the most in.Over time you get a feel for what fits best.

While we are talking about this one develops over the years a feel for what size stilts to use with out measuring and what fits best form wise per given space. I never have to measure how tall a piece is-You just know-this skill takes many years to get dialed but it does come with practice.

If your forms are warping in a bisque they are either still wet or real thin-super thin forms take more care in all regards.Back in my school days a friend called them potato chips when he saw my work-I gave that up long ago for stronger daily use functional forms which are thicker.

Mark

 

 

 

 

The only problem I have of late with the tumble stacking is that I take forever to fill a bisque load, and then it takes forever to glaze all of the pots. I used to not use shelves in a tumble, as I said before, just distributing weight. Most HS student pots are heavier than "potato chips"!

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Lucille Oka    16

Lucille I didn't know you had such a great sense of humor, good luck with your stack firing. I have stack fired before and didn't have any problems, I plan to have a stack firing in a couple of weeks myself. Denice

 

 

 

 

 

 

 

 

smile.gif

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weeble    5

Yikes, that takes guts. I stack, I wedge stuff in, I pile em up, but that... OY. I'm firing for a very mixed group, all handbuilding, and I know there are a lot of very delicate sculptural pieces and some real doorstops in every load. The other end of it is we just plain run out of drying room LONG before we have that big a load of bisque! LOL Good to know its not really a problem to do though!

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Lucille Oka    16

Okay the firing was fine. I had planned to do three vessels but one vessel was not ready. It had to get a coat of underglaze to be hardened on and could not be placed on or touching the others due to possible fuming. So I just placed one vessel on top of the other with large posts used as props on either side of the two vessels. Also the two vessels were lidded and cylindrical one of them in particular had to keep the lid in place as it fired horizontally. the other lid was placed inside the bottom vessel. There was a bit of fuming from the bottom vessel to the top one. But that is okay the top one will be given a covering of an opaque glaze. Sorry I can't give you pictures; not set up for it.

 

A stacking of two cylindrical vessels was not much of a stretch of courage, but I was antsy about the props moving but since this was a first stacking and it did well, I will try it again.

 

Thanks a lot for sharing to- Mark, Neil, Marcia, Denice, and Pres "The Pot Stackers". I hope I didn't miss thanking anyone it was not intentionally done.

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emptynester    2

Question: Does it take longer to reach final temperature with this much mass? Or, is it more efficient because the clay holds temperature better than the empty air spaces in a loosely filled kiln?

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we use Alumina on our kiln shelves. They are not removed between firings, and thus the shelves need to be stored horizontally. But, to prevent the alumina from sticking to the bottoms of the shelves, we made little 6 mm high disks out of clay. 3 on each shelve, and you can stack 20 - 30 shelves. I use those little discs for stability when I stack my bisque kiln, because I am always scared that my vases, etc will roll around. I can almost fill my 15 cubic with glazed work from my 4.5 cubic bisque kiln.

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