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Opinions on electric Kiln loading


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Happy New Years everyone!

 

I'm writing to you all because recently an kiln in my college studio was loaded, and there was difference of opinions on what was "wrong" with the loading. In the following image the kiln was loaded with an mixer of bricks and some of the brick are the soft white bricks (the white bricks seemed to be made of the same martial as the bricks used within the kiln, surrounding the elements!). (Due to the weight along with height of the pieces The bottom two kiln trays was loaded vertical yet the top kiln trays were loaded horizontal (due to the fact that the pieces are heavier the trays were positioned within the kiln horizontal, which was thought to hold the pieces securely within the kiln!) I am open to read everyone's thoughts and ideas and they will be an great help, to myself and my classmates!

post-8794-132557234227_thumb.jpg

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I don't like to put the load on different spots of my shelves. The posts at the bottom are set on the inside of the shelves and run perpendicular to the upper shelves which are supported on the outside. The front and back corners have a lot of weight on them and are not supported. If I had loaded that kiln the shelves would all go the same way and the supports would be directly on top of one another.

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I couldn't open the larger pic and not sure if that is a support in the center front.

To me it looked like the posts were creating a fairly good obstacle from the elements in an electric kiln where the heat is radiated. I like to use 3 posts per shelf because 4 posts can warp a shelf. Having loaded some very heavy pieces this semester I can understand the concern to support the shelves.

I would use thicker shelves for heavy pieces, but I'd use normal posts. As Benhim points out, there is a long span across the shelf which would have been avoided using 3 posts with one in the center shelf. As always posts must rest on posts beneath the bottom shelf. I can't tell what was under the bottom shelf but that is where a big accident could happen if the shelves don't follow the same pattern throughout the kiln.

Marcia

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Those bricks are blocking the heat ... You should use the appropriate kiln furniture. Also, the work on the top shelf is almost touching your pyrometer which could give an inaccurate reading on the inside kiln temp. I would have put the shorter work on the bottom shelf so you wouldn't have had the high rise wobble. I would also have a lot more stuff in it!

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It has been my experience that when loading a kiln, if the kiln posts are not stacked directly above each other you are potentially gambling with a broken shelf due to the stress. Corners break off all the time if not supported.

 

I have witnessed this when a broken shelf in the middle of a large load caused the domino effect of every shelf beneath to become broken and the entire load ruined.(this was a case of a student not following the rules of kiln loading. Hard lesson learned.)

 

Also, the use of soft brick for posts can cause the posts to stick to the shelf above and make unloading difficult and mar the surface of the soft brick. (unless of course you used a cookie)

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Chris is right about the loading. If you had the tall piece in the top curvature of the arch you could get about set pf shelves in there.Plus there should be more work in there to be energy efficient.

Marcia

 

 

Beyond being more energy efficient the electric kiln requires tighter packing for more even firing. Radiant energy heating up the outer pots heating up the inner pots.

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My school teaches us to avoid placing a pot on the crack between 2 shelves..but I'm not sure why.

 

 

In an electric kiln there are two reasons:uneven support, uneven heat and thus expansion/contraction. However when dealing with a fuel burning kiln the open areas between shelves are path ways for flame that you don't want to block unintentionally.

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In any kiln I've ever fired the fullness made a huge difference in firing. When the big down draft kilns are full they fire much more evenly. I often had poor results out of these kilns in college when students who didn't know how to load would loosely pack the kiln. If I could catch it before lighting I'd often get another 50 or more pots into an already loaded kiln.

 

I've never been able to fire a cross draft that wasn't tight on the bottom and evenly packed as possible through out. Any open spot is a flow path that diverts the flame from another section of the kiln leaving cold and hot spots. The salt kiln in college had this problem severely because the stack was huge and would easily draw the small gas flames from the two burners straight through.

 

In my electric kiln any open space is cooler creating uneven heating. This is especially troublesome on larger pots and glazes that have a hard time maturing. Recently I had a pot close to the elements in a loosely packed kiln. Three bands that were close to the element matured, the rest of the pot was under fired.

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I always stagger shelving height in my Skutt 1027 for heat work flow. I installed an Envirovent last summer. Amazing results and such a boon to studio through put; which means I can remain in studio and continue working rather than fire at night. I place props directly underneath each other and use a tripod system. I leave at least 1/2" between pieces, I leave about 2" around thermocouple probe and without fail raise shelving so that it is above 2" distance. It's a pain sometimes to load, and sometimes pots get left out for the next firing. I keep a Kiln Log and make notes about Start times, general glaze notes, ^? firings, weather conditions, pieces loaded and load amounts" 3/4 full etc. I also keep a Workshop Journal for the year and make more exhaustive notes about results of glazes etc. I correlate Journal and Log with a numbering system so that X-referencing is easy. I do try, as Marcia suggests above, to assimilate enough for a tightly packed kiln.

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I will add my take-

1st posts always should line up from bottom to top of load-you will see the lower short posts are not lined up with your soap/brick/stilts-in a cone 10 gas fire these shelves will warp or crack if you ever load it this way

2nd-use real posts not bricks -this kiln furniture is way to oversize for this electric

3rd-use your space more efficiently

here is an example-this kiln gets loaded 35 glaze fires a year like this-try to use all the space

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Kiln posts should always align vertically, so they carry the weight. No more than 3 posts per shelf, no matter how big the shelf is. Posts should be at least 1" from the elements and thermocouples. Hard brick can be used as posts, but NEVER use soft bricks (IFB, like the kiln is made of). They cannot hold any weight and may shear off. You don't have to stagger the height of half shelves. Pots can sit on the joint between half shelves as long as the shelves are very even. Otherwise the pots will warp. You don't have to leave a gap between half shelves. Keep it simple....

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  • 1 month later...

Hello everyone! Thank you all for your commits, and help. My laptop broke on me and i'm currently in writing an thesis paper, plus i'm in the process of creating pieces for my final visual thesis! Please, please keep leaving your thoughts! I realize at this point I shouldn't be so scared of the kilns but I am! I have an hard time remembering how to program the electric, and don't even get me started on the gas kilns. I find them so confusing and I've read paper works yet I still don't get how to use them, and I need to use them since I'm working in stoneware clay.! Again your thoughts are very much welcomed!

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