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Tumble stacking the bisque-electrics


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Tumble-stacking is really sweet, but it is possible to warp things in bisque.

 

I make square slab-built plates without feet.  If there is a draft on them during drying, a corner will lift, and they rock a little.  Once I was testing for warpage on dry greenware, and found that the plate would bend and become flat when I pressed on it.  So I loaded it on the shelf and put heavier things on top of it to flatten it.  After the firing, it was flat.  The bisque firing had set the deformation.

 

Barb

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Seems I need to clarify a bit more. My clay Is high fire porcelain. Thios kiln is a skutt 1227.

I have 6 -1/2 shelves in that load. That is the number I usually use in bisquing. I fill all the space on every layer. Pots are always pretty dry.

As to warping Its never been an issue. If they did warp which they do not they woould flatten out in high fire at cone 11 .My intent is you can load more than you may think in a bisque fire as long as the work is dry.Clays that have contaminates can cuase issues so testing your body is always a good idea.

Many folks stack a bisque like a glaze fire and that is wasted space in my world so try stacking more into a bisque and see what may be possible.

Mark

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  • 1 month later...

I usually stack plates 5 or 6 high. You just have to make sure the foot ring is carrying the weight of the pieces above, not the lip.

 

The thing you have to watch out for is stacking flat pieces without any sort of air gap between them. Stack six 1/4 inch tiles and you've essentially created a 1.5 inch thick block that the heat will not be able to penetrate very easily. Use spacers or stand them up.

 

Pieces should not warp much at all in the bisque, because the clay is not getting anywhere near its maturation point. If they do warp, it's probably a case of unevenness in the construction.

 

As long as there is space for the heat to get through, you can stack as high as you want, assuming the pieces can handle the weight.

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I regularly stack small platters, 9x12 inches up to 6 high. I stack them face to face and bottom to bottom, creating air pockets inside where the 2 face to face platters meet, I usually place pendants or ornaments inside this face to face sandwich. Doing this I stack up to 3 sets of platter "sandwiches". I then fill in around the stacked platters with other smaller items also stacked up to the same height. I only use 3 shelves in my tumble stacked bisque loads counting the bottom of the kiln shelf. I haven't had any issue with warping or cracking doing it this way.

 

I should also mention I do a slow bisque to ^04, use Little Loafers, and my pieces are generally hand built with a max thickness through the slab roller of 3/16 of an inch and some down to less than 1/8. I am always trying to figure out more efficient ways of firing and tend to keep shelves of work in the various stages ready for the next step so I can fit as much in as possible whether it's bisque, glaze or transfer.

 

Terry

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  • 5 months later...

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

WOW! That blows my mind. I would have never thought this possible if I hadn't seen it with me own eyes. Amazing. You got me thinking. Thanks Mark. 

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Marko-my book is here -right here on this forum

My book is (Everything you need in a used car kiln) by Frank

Frankly speaking; I'm sold. What better book can we have, that we can not share, in person. Thanks my good man. Cheers. 

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