Electric Kiln Design: 'bucket' Or 'box' Preference?

[Mudslinger Ceramics]

Hi all

 

Read the forums often and it seems US potters firing electric kilns favour  6/8/12 sided or oval, top loading kilns mounted at floor level....('bucket')

The ceramics supply websites also seem to favour them, though I have only seen one or two front loading, square/rectangular designed kilns raised up on stands ....('box')  offered recently. 

 

In Australia we favour the 'box' design (with or without kiln elements mounted in the door and almost always accompanied by an computer controller) with only our main manufacturer offering a 'bucket' line but these do not sell well.  Not sure about Europe or UK but would love to know.

 

Have wondered why the difference?    Is it just what manufacturers make?  local/state availability?  price? .....or is there a real difference in the firing?

 

Potters who have fired both kinds of electric kiln design please tell us your preferences... 'bucket' or 'box' design... and why, or when, you prefer one to the other?        Manufacturers, your view?

 

 

thanks

Irene

[atanzey]

From my own experience (limited as it may be), I have a 23" multi-side, top loading electric kiln and an 18" top loading gas kiln.  The segments mean that I can unstack, move, replace elements, etc. 'all by myself'.  I assume that moving a rectangular kiln would require mechanical methods, although I don't know for sure.  And then, for some reason there's a pretty steep price increase for front-loaders, from what I've seen. 

 

Alice

[neilestrick]

Front loading kilns are much easier to load and unload, and definitely save a lot of stress on the lower back. However, they require much more engineering to build them, and a sturdier, heavy duty welded frame that can support a hinged door. The bricks in front loading kilns are usually mortared together for stability, with an arch for the ceiling. All of these things add up to much higher costs than top loading kilns. Plus front loaders do not come apart in sections, which means they must be moved into place with a pallet jack or fork lift, and are therefore not able to be put in home basements, or easily rolled over thresholds into a home studio. It is rare to see front loading kilns larger than tiny test kilns anywhere other than schools.

 

Round, top loading kilns are held together with a stainless steel sheet metal jacket that is tightened up by clamps. The only part of the kiln that is welded is the stand. The bricks are cut into wedges to make the round shape, which also negates the need for mortar. They come apart into sections that can be carried by one or two people into basements, studios, broom closets, etc. The engineering is simpler, and the labor to produce them is considerably less. Therefore the price is considerably less.

 

Comparison:

L&L Hurcules 9 cubic feet front loading kiln: $8500

L&L E28T-3 10 cubic feet top loading kiln: $3450

[Pres]

Neil has a great explanation of the economic advantages and the ergonomic dissadvantages of our US preference for the "bucket" type kiln. I would love to own a large box with a door, but can afford a large bucket with a lid. I have also gotten used to the versatility of using 2, 3, or 4 sections of my kiln to save on space and electric costs. This became even easier when I added two handles to my lid, and removed the hinges.

[DAY]

 I have often wondered why the big price difference, so neil supplies the answer!

 

Now the question is why buy a front loader? Surely, unless one is physically handicapped, the front loader is not that much better.

a 20 cu/ft gas I understand, is better from a design standpoint,  but not an 10 foot electric.

[Benzine]

 I have often wondered why the big price difference, so neil supplies the answer!

 

Now the question is why buy a front loader? Surely, unless one is physically handicapped, the front loader is not that much better.

a 20 cu/ft gas I understand, is better from a design standpoint,  but not an 10 foot electric.

Because, as Neil said, loading in a front loader, reduces strain on your back, when compared to a top loader. 

 

As someone, who has spent the past several years, loading large, heavy, awkward shaped student projects into a kiln, not to mention all the shelving, I can definitely see, where a front loader would be fantastic. 

 

Sadly, I don't see me getting one anytime soon.  Plus, I'm still young, so if I take the proper precautions, and lift things smartly, I'll be fine......Hmmmm, I should probably start saving for a front loader now.....

[neilestrick]

It's also easier to load large sculptural pieces into front loading kilns. However you can always unstack the rings of a top loader, set the sculpture onto the floor slab, then lower the rings over the piece to reassemble the kiln. L&L makes a kiln designed for this with a freestanding control box and sections that unplug. It's way less expensive than a front loader, and you can choose how many rings you want to use or each firing.

[Marcia Selsor]

My big oval doesn't have removable rings. too bad.

Rudy Autio had an electric hoist he used to lower his large vessels into his top loader.

I love that idea.

 

The front loader does look like a back saver. Thanks Neil for that explanation.

 

Marcia

[Benzine]

My big oval doesn't have removable rings. too bad.

Rudy Autio had an electric hoist he used to lower his large vessels into his top loader.

I love that idea.

 

The front loader does look like a back saver. Thanks Neil for that explanation.

 

Marcia

Not only a back saver, but a gut saver.  I have to hang over the edge of my classroom L&L, to get things loaded into the bottom.  My feet sometimes come off of the surface I am standing on.  It probably looks a little precarious, and I've had students ask, "What would happen if you fell in?"  They seem to thing, that I would be consumed in fire, like if I fell into a pit containing a mixture of lava and acid.  I tell them, "If I fell in, I would have to fall in hard enough to cause me to squeeze all the way in, the lid would have to close and magically lock behind me, someone, who knows how to use the control panel would have to start the kiln, and I'd have to be incapacitated long enough, that I didn't try to get out, before the heat/ electricity would kill me.  So basically, nothing would happen more than me looking like an idiot, as I struggle to push myself back out."

[Mart]

"Bucket" I like this word. It is very descriptive.

 

All bigger (>100 l ) kilns I have seen around here are front loaded box kilns with flat roof. It is a bit hard to believe that "more engineering" is required for building a flat roof to a square front loader than flat moving lid/roof for a round top loader

 

I have a small top loader.  Circular design is a huge waste of staking space.

It's is easy to imagine why. Just draw a circle with a diameter of 10 and now draw a square with a edge length 10

http://www.wolframalpha.com/input/?i=square+side+10+and+circle+diameter+10+calcualte+area

 

Next kiln will be front loading box.

 

Btw, I started to pre-load the shelves on my work table. Place the posts and then the pieces on the shelf,  lift/lower loaded shelf in to the "bucket" and repeat for the next shelf until the kiln is full. Much better than hanging over the edge of the kiln while placing stuff at the bottom of the bucket. Works for me.

[JustaWhittle]

I can imagine a front loader would be better for different situations for sure!  I have to have my partner load the top loading kiln as I am currently 7 months pregnant... luckily I have a very understanding man who loaded for me but I can imagine depending on certain physical constraints how it would be worth the extra costs of the front loading kiln

[OffCenter]

A front-loader can be a strain, too. Like which is harder, holding a shelf straight out to position it on posts or lowering it down to the posts? While I agree that a front-loader is easier to load, I remember that when I was in school the front-loader was considered harder to load than the bucket kiln.

 

Jim

[neilestrick]

All bigger (>100 l ) kilns I have seen around here are front loaded box kilns with flat roof. It is a bit hard to believe that "more engineering" is required for building a flat roof to a square front loader than flat moving lid/roof for a round top loader

 

While a flat slab is simple, a welded steel frame that can support a hinged door is not. Getting a tight brick-to-brick seal on the door is no simple matter, either. It all adds up to more labor, more materials, and higher prices.

[neilestrick]

A front-loader can be a strain, too. Like which is harder, holding a shelf straight out to position it on posts or lowering it down to the posts? While I agree that a front-loader is easier to load, I remember that when I was in school the front-loader was considered harder to load than the bucket kiln.

 

Jim

Reaching into the back row of a front loader can definitely be a strain. I have a friend who loads the back row first, so he can climb into the kiln, then loads the front row. Slightly less efficient use of space, but well worth it at age 65.

[Benzine]

 

A front-loader can be a strain, too. Like which is harder, holding a shelf straight out to position it on posts or lowering it down to the posts? While I agree that a front-loader is easier to load, I remember that when I was in school the front-loader was considered harder to load than the bucket kiln.

 

Jim

Reaching into the back row of a front loader can definitely be a strain. I have a friend who loads the back row first, so he can climb into the kiln, then loads the front row. Slightly less efficient use of space, but well worth it at age 65.

 

I guess that's why car kilns come in handy, no limited access when loading.

[Pres]

Considering the size of my bucket, not a lot of strain, even when using 4th top ring. If i were loading a 25+ cu I would not want a bucket.

[Arnold Howard]

A front-loader can be a strain, too. Like which is harder, holding a shelf straight out to position it on posts or lowering it down to the posts? While I agree that a front-loader is easier to load, I remember that when I was in school the front-loader was considered harder to load than the bucket kiln.

 

Jim

If you load the same size ware from one firing to the next, you can leave the shelves and posts in the kiln between firings. Reach in between shelves to load and unload the ware. Use half shelves instead of full shelves.

 

Sincerely,

Arnold Howard

Paragon Industries, L.P.,

Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com

[Claypple]

 

 Circular design is a huge waste of staking space.

It's is easy to imagine why. Just draw a circle with a diameter of 10 and now draw a square with a edge length 10

 

Do you make square bowls? No. Does the heat from the elements stops at the corners? No.

That is why the "bucket" kilns are more efficient than the "box" kilns.

(And that is why everybody should be obligated to take a science class while in school!)

[OffCenter]

 

A front-loader can be a strain, too. Like which is harder, holding a shelf straight out to position it on posts or lowering it down to the posts? While I agree that a front-loader is easier to load, I remember that when I was in school the front-loader was considered harder to load than the bucket kiln.

 

Jim

If you load the same size ware from one firing to the next, you can leave the shelves and posts in the kiln between firings. Reach in between shelves to load and unload the ware. Use half shelves instead of full shelves.

 

Sincerely,

Arnold Howard

Paragon Industries, L.P.,

Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com

 

 

I don't load the same size ware from one firing to the next and don't have a front loader. In Denver I loaded a two-car Alpine train kiln that way. I took the shelves off once a month or so to clean and kiln wash.

 

Jim

[Marcia Selsor]

When I was teaching, I bisque fired in bucket kilns and glazed in a large car kiln or a 30 or so cu ft sprung arch front loader. For over half the semester I fired the glaze loads four times/week. Not much help towards the last years of teaching due to higher tuition and students needing to work more jobs out of class time. I never left the shelves in the kiln. Student work always varies in size. Loading and unloading was so routine, I just did it. I always liked loading to fit the maximum in any firing. Sometimes rearranging several levels as more work was brought into the kiln room.

I did like the large car kiln the best I think as far as the loading of shelves.I am 5'2".I would kneel in the sprung arch kiln to load the back column of shelves, then then front.I have to say the worse loading experience was 2 years ago when I was teaching at UTB. That was a huge Olsen kiln with 4 columns of 1" 18 x 18" shelves. That took a while.I had to stand inside to load it.

 

Marcia

[Mart]

 

 

 Circular design is a huge waste of staking space.

It's is easy to imagine why. Just draw a circle with a diameter of 10 and now draw a square with a edge length 10

 

Do you make square bowls? No. Does the heat from the elements stops at the corners? No.

That is why the "bucket" kilns are more efficient than the "box" kilns.

(And that is why everybody should be obligated to take a science class while in school!)

 

 

I throw them square... no, those are actually cubes. Yes, I throw cubes <--This was a joke

 

LOL, you kinda proved my point, actually.  You see, the corners of a rectangular shelf are perfect for posts (or pots, if posts are in the middle). But when you add posts to a round shelf, what happens then, Mr SleepingInGeometry?

Cheers!

[jrgpots]

 

My big oval doesn't have removable rings. too bad.

Rudy Autio had an electric hoist he used to lower his large vessels into his top loader.

I love that idea.

 

The front loader does look like a back saver. Thanks Neil for that explanation.

 

Marcia

Not only a back saver, but a gut saver.  I have to hang over the edge of my classroom L&L, to get things loaded into the bottom.  My feet sometimes come off of the surface I am standing on.  It probably looks a little precarious, and I've had students ask, "What would happen if you fell in?"  They seem to thing, that I would be consumed in fire, like if I fell into a pit containing a mixture of lava and acid.  I tell them, "If I fell in, I would have to fall in hard enough to cause me to squeeze all the way in, the lid would have to close and magically lock behind me, someone, who knows how to use the control panel would have to start the kiln, and I'd have to be incapacitated long enough, that I didn't try to get out, before the heat/ electricity would kill me.  So basically, nothing would happen more than me looking like an idiot, as I struggle to push myself back out."

 

Stories of Hansel and Gretel come to mind.  The evil witch potter loading his kiln is kicked into the hot bowels of the consuming kiln's fire... More details at 10:00.

 

I have seen a homemade kiln made from a "bucket" style.  The kiln had been cut in half along the midline vertical plain and hinged.  I don't know how the bricks were stabilized.  Half of the kiln swung open like a front door.  Has anyone else seen this type?

[Claypple]

 

 

 

 Circular design is a huge waste of staking space.

It's is easy to imagine why. Just draw a circle with a diameter of 10 and now draw a square with a edge length 10

 

Do you make square bowls? No. Does the heat from the elements stops at the corners? No.

That is why the "bucket" kilns are more efficient than the "box" kilns.

(And that is why everybody should be obligated to take a science class while in school!)

 

 

 You see, the corners of a rectangular shelf are perfect for posts (or pots, if posts are in the middle). 

 

Take, e.g. an electric element as long as 100cm. If you put it in a square shape, you will have a kiln with the surface of 625 sq cm. (25x25=625) If you put it in a round shape, it will give you a circumference of the kiln of 100cm, which is equal to a circle with the diameter of:    100 : 3.14 = 31.847 cm.    Then the radius of this circle will be 31.847 : 2 = 15.9 cm The area (surface) of the round kiln then will be: 15.9 x 15.9 x 3.14 = 793.8 sq cm.

Now compare the numbers: Square kiln: 625 sq cm. Round kiln: 793.8 sq cm. 

Since the amount of electricity/energy going through the 100 cm electric element is the same in both round and square shape, the round kiln will be 27%more efficient.

 

By putting the posts in the corners you are simply "smoothening" the corners to more round shape. You are actually doing opposite to "squaring the circle", but there is always a lot of available space in any kiln for the posts between the bowls.

[Mart]

 

 

 

 

 

 

 

 

 

 

 

 

 Circular design is a huge waste of staking space.

It's is easy to imagine why. Just draw a circle with a diameter of 10 and now draw a square with a edge length 10

 

Do you make square bowls? No. Does the heat from the elements stops at the corners? No.

That is why the "bucket" kilns are more efficient than the "box" kilns.

(And that is why everybody should be obligated to take a science class while in school!)

 

 

 You see, the corners of a rectangular shelf are perfect for posts (or pots, if posts are in the middle). 

 

Take, e.g. an electric element as long as 100cm. If you put it in a square shape, you will have a kiln with the surface of 625 sq cm. (25x25=625) If you put it in a round shape, it will give you a circumference of the kiln of 100cm, which is equal to a circle with the diameter of:    100 : 3.14 = 31.847 cm.    Then the radius of this circle will be 31.847 : 2 = 15.9 cm The area (surface) of the round kiln then will be: 15.9 x 15.9 x 3.14 = 793.8 sq cm.

Now compare the numbers: Square kiln: 625 sq cm. Round kiln: 793.8 sq cm. 

Since the amount of electricity/energy going through the 100 cm electric element is the same in both round and square shape, the round kiln will be 27%more efficient.

 

By putting the posts in the corners you are simply "smoothening" the corners to more round shape. You are actually doing opposite to "squaring the circle", but there is always a lot of available space in any kiln for the posts between the bowls.

 

 

 

This picture looks like a test for a color blind but it's not. This is a quick Qcad drawing of our imaginary kiln, using 100 xyz long coil

 

 

Here is the legend:

Blue outer square - wall for our imaginary kiln

Red - 4 coils, each 25 xyz long

green circle - bucket kiln wall (100 cm circumference for the coil)

White square with 4 white circles - kiln shelf with 4 posts

Yellow circle with green lines - round kiln shelf with 3 posts (small yellow circles)

 

Square shelf has approximately 22% of more stacking space, while surrounded by that same 100 xyz coil.

 

PS! Pleas, do not take this personally. As I have said before, I sometimes miss the nuances of English language and can sound a bit harsh It is not my intention.

[Claypple]

You sound very nice, no harshness at all. I like your diagram, too, but the round kiln would not be inside of the square one. (See theorems for "squaring the circle" ). That is your main mistake.

 

What you drew would be very important if you had only one huge bowl/platter you had to place on one shelf. The reality is we are all stacking multiple, different size objects, so there is plenty of room for the posts in between of them.

 

You have a very good point, but only if your work is a very large round  bowl or platter that hardly fits into the kiln.