Tumble stacking the bisque-electrics
Posted 08 April 2015 - 03:11 PM
The kiln finished firing, it took exactly 15 hours to run my load of tumble stacked bisque. I looked at my log and it usually takes 13 1/2 hours to run. So if I add the 1 hour preheat I added to the normal cycle it took 30 minutes longer to run the tumble stacked load. Is it because there was a LOT more in there? I usually use about 5 shelves I only used 3 this time with my taller posts and stacked as much as I could onto each shelf. I lost count since I kept having to go find more pieces to add but plan to count how much I got in there and try to compare it to my usual loads. I am betting I get 3 glaze loads out of this 1 bisque.
Posted 08 April 2015 - 03:32 PM
Well there you go Pugaboo looks like you are to something good. Just think of all the savings.
By the way I usually use about 3-4-5 shelves when doing this in the big skut 12227 kiln. I tend to do this in the gas kilns as well-I stuff until you cannot stuff anymore.Never could figure out the waste of doing it the Traditional way taught in schools once I figured it out.
Thanks for redeeming me.
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Posted 08 April 2015 - 06:21 PM
good for you, i have seen stuff just piled all over the place without any shelves. these were identical commemorative items about the size of quart size vases. they touched the walls from side to side and there were no posts at all. it does work. i think the design and sizing was done with this kind of firing in mind. the glaze firing was uniformly spaced on shelves with 6 inch posts.
Posted 09 April 2015 - 05:18 PM
Emptied the kiln and everything came out perfectly. No cracks, warping or mystery happenings. Yay!
I added up everything I had in there and I was able to fit $2300 worth of saleable bisque into my little 18x23 electric kiln. I added up how much I got the last time I ran a load and it was only $935 worth. Tumble stacking is WORTH IT! I am staggered by the difference. I know I can fit even more in there with a bit of planning and having on hand a wider variety of pieces to fit in different shaped spots and inside other pieces.
I glazed some of the pieces I had in the tumble stacked load and am firing them now. This should be a good test to see if I have any issues with pinholes or not. Everything is a test at this point so I guess it's wait and see.
Posted 13 August 2015 - 12:10 PM
I need to fire 88 terracotta tiles. I own four shelves, and sufficient posts to hold them up. I can get 7 tiles to a shelf without stacking.
The tiles are all slightly dished/warped, all the same way up. (Trying to dry them just enough for the scouts to carve them....only one arm in use for 9 weeks..... other arm not strong enough to do much..... excuses, excuses.....)
1) stack them the same way up in overlapping layers
2) stack them face to face in overlapping layers
3) stack them the same way up directly above the one below
4) stack them face to face directly above the one below
5) not stack them at all, and fire the kiln 4 times
6) stand them all on edge - scary
Posted 13 August 2015 - 12:53 PM
for bisquing tiles our techies always stack them on edge. allows them to shrink without cracking. once someone stacked a load of tiles flat and on top of each other and they cracked. on edge is best - at least for stoneware. our studio has a tile class and they always stack on edge. ditto when I raku fire flat pieces. rakuku
Posted 13 August 2015 - 03:52 PM
With fast shipping you may be able to get tile racks (that hold them vertically), depending on your deadline. Not terribly expensive either.
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Posted 13 August 2015 - 10:01 PM
You'd get a lot more in if you stack like Marcia posted, vertically supported by posts. I have a number of triangular prisms, that I use as stackers between tiles. Someone will know what they're called.
Posted 14 August 2015 - 05:27 AM
You never want to make anything to thick by having their surfaces touch, I have had bisque over fire that way and even start local reduction. Workable but a pain. Might have been down to my bisque temp and clay too.
Stacked some tiles with my smallest stackable kiln props once, worked for bisque.
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Posted 14 August 2015 - 05:35 AM
OMG I've never heard of doing such. There are 3 shelves in that kiln? When I saw the picture I thought it was some kind of prank. Can't believe I have missed this information.
Posted 14 August 2015 - 09:02 AM
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.
- Rae Reich likes this
Posted 14 August 2015 - 05:37 PM
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.
Posted 16 September 2015 - 03:07 PM
I'm just worried they warp and the weight on the bottom ones makes them crack....
Posted 21 September 2015 - 08:47 AM
I will have to try more of this but am a little concerned. The only time I have had pieces break in a bisque fire was when they are stacked 3 high. Made a bunch of square plates and finally decided to stack 2 and lot my first one, now I wonder why.
Posted 21 September 2015 - 01:19 PM
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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Posted 21 September 2015 - 03:50 PM
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.
Posted 21 September 2015 - 09:06 PM
wow, terry! where is that scared person who had just started working with clay 3 years ago?
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