Kiln Building Materials and Design

Bert Weiss · Post by **Bert Weiss** » Sat Nov 08, 2003 12:34 pm

elin wrote:I work at EK Miller Co. in Portland. We build FuseStar kilns, which have the cooling system Bert described-- and there are quite a few of our kilns in use in the area, and also in the bay area. I think it works great-- cool air is never actually being introduced into the kiln, but heat is being removed quickly. The elements are wound on the outside of the quartz. There are also venting chimneys on the roof of the bell, if you need to crash cool the glass surface.

I'm not an expert, but I have some experience, and I have a few answers for you--
1) You do not need three-phase power to have quartz elements.
2) 12" might be too low for some things, but you can build up a brick wall to increase the height-- Just don't skimp on power if you want that flexibility.
3)A multi-zone controller can be a very nice luxury, but it should not be necessary-- you'll be able to tell if the heat is uneven.
4) Mercury relays tend to be more reliable, but solid state ones work well too.
5)I strongly reccommend a movable bell. Once you have your pieces carefully laid out, the last thing you want is for your table to hit a bump while you roll it into place.-- You always have the option of building a second table later.

I have also used Glasslam, and have always had success with it-- even on contoured surfaces. I hate gluing! But it seems to work.

Anyway, good luck with the kiln

Elin

I was talking with the engineer at Duralite about the open quartz tube design. He saw no reason not to use the same design but with the elements wound inside the quartz tubes.

I use an element design that uses nichrome wire in straight lines, not coiled. It is much less expensive to make than quartz tubes and coiled Kanthal. I am thinking however about retrofitting my kiln with a set of empty quartz tubes to do the heat exhaust thing.

I would think that using a multi zone controller to activate a relay that activates a fan at the point where the kiln is cooling slower than the program, would be a good idea.

I plan on using SSR relays on our next kiln building project. They cost less than mercury and are considered much better. Click click relays wear out pretty fast especially relative to SSR's which are electronic and if installed properly (not on the kiln, but on a nearby wall) they will last long and do a good job.

I would choose SCR relays if I had the choice. They are more sophisticated than SSR's, but require a 4 - 20 milliamp signal to activate them. At present The Bartlett Controller does not support this output. IT does support a signal that will run the SSR.

elin · Post by **elin** » Sun Nov 09, 2003 2:46 pm

Well Bert,
The truth is, I build the things, but I do not design them. I am still learning as I go, but for now, I basically do as I am told... I wish I had more information for you.

I'm not sure if having the elements inside the tube would be problematic.

I don't know anything about straight elements-- but it seems like you could have the exhaust tubes regardless of what your elements are like.

A multi-zone controller sounds like a luxury that I have never had the opportunity to use-- sound nice though.... It sure would give you more controll.

And, unfortunately, I don't really know all of the factors that go into choosing relay types.

I do strongly reccommend a rolling bell, rather than table... that much, I do know, from first-hand experience.

I wish you all luck with your kiln projects.
-elin

Bert Weiss · Post by **Bert Weiss** » Sun Nov 09, 2003 3:19 pm

elin wrote:
I do strongly reccommend a rolling bell, rather than table... that much, I do know, from first-hand experience.

I wish you all luck with your kiln projects.
-elin

I totally agree with you about the rolling bell as opposed to a rolling floor. I made my kiln with a stationary floor. The bell goes up and down and back and forth on a rolling gantry. It works great.

The next project I am involved with will have a stationary floor and the bell will go up and down, attached to the ceiling. This should be OK in the setting it is being installed in. There will have to be a redundant support system so that there is no chance of getting one's head removed while loading the kiln. I'd hate it if that happened.

Another good idea would be to have an I-beam attached to the ceiling and have 2 floors. The bell could be rolled back and forth between the floors so the next one could be set up and waiting.

Another important aspect of having a non moving floor is the ability to adjust the level at several points around the perimeter and in the middle as well. A level floor surface is the starting point to successful work.

I am designing a mini kiln that can be plugged in to 110. It will have 2 floors so that one can lift up the mini bell and put it down on a safe spot no matter how hot it is.

Tom White · Post by **Tom White** » Sun Nov 09, 2003 3:34 pm

Bert, that 110V mini kiln sounds very interesting. Please be sure to keep us informed on progress.

Best wishes,
Tom in Texas

Dean Hubbard · Post by **Dean Hubbard** » Sun Nov 09, 2003 4:04 pm

[quote]elin wrote There are also venting chimneys on the roof of the bell, if you need to crash cool the glass surface.

Elin, are the venting chimneys manually opperated, or are they tied into the programmer? One of the kilns I looked at was indeed a FuseStar.

[quote]Bert Weiss wrote Another important aspect of having a non moving floor is the ability to adjust the level at several points around the perimeter and in the middle as well. A level floor surface is the starting point to successful work.

Bert, I couldn't agree any better on this one. At first when I contemplated having a rolling table on a fixed track, (Mainly for sliding it up against a wall while not in use) I considered over building the lower support section of the table with traingulation bracing. (One of the unique situations I have in my shop is, since this was previously a fire station, the shop floors all have a slope for water drainage) I have since scrapped that idea, due to the floor conditions and weight of glass considerations. One thing I will certainly use when leveling the table up during construction, is a rotary lazer level set on a tripod. I used a seven foot door level to level up my pouring table (5' x 10') for laminating glass. I had to get a lazer level and reset all 148 swivel casters after the first attempt at pouring a 60" x 96" piece of laminated glass. (My 7' level didn't show a very slight twist in the table top)

Thank You for all the input folks.
(I'll use the quote feature correctly next time, now that I read how it works)

charlie holden · Post by **charlie holden** » Sun Nov 09, 2003 6:29 pm

glazinguy wrote: I only have two decesions to make at this point.
1. Insulation configuration. I like the products I see at the unifrax site, hd and ld boards, fiber blankets, but I wish I could get a response from this company out here, to find out sizes available. I'm hoping to use a one piece board on top of the IFB.
2. Interior size and configuration of bell. I'm leaning towards going 48" x 90" x 12". It would have be nice to slump a stock sheet of float 48" x 96" however, I didn't consider the need for extra spacing around the perimeter. I think this way with a 48" x 90", I'll be able to easily fit a 42" x 84" piece of float and be able to also get a 46" wide piece if needed. Also this size got me down to a 150 amp. requirement which is well below the 20% underage of my 200 amp service.

1. Are you talking about using fiber board as your kiln shelf? Unifrax LD board makes a pretty good shelf. I think it comes in 104" x 60" sheets but may be a special order for most distributors. If you're just talking about insulation for the bell, there are lots of companies that make comparable fiber products. I think 4 inches of blanket is fine. Try Thermal Ceramics, AP Green (HRI now I think), Lytherm. Look in your yellow pages for refractory supplies. There will be several in any city of any size.

2. You probably know a lot more than I do about what sizes of glass are ordered most. I don't know if it would be worth it to be able to slump a 48" wide piece or not. The biggest piece I can do is about 65"x 36". I figured the actual outside dimension of my table based on how 9"x 4.5" bricks lay out so that I only cut bricks in half and cut as few as possible. So, shooting for close to 48"x 90" inside dimension I would lay out a table that is 11 bricks long (99 inches outside) by 13 bricks wide (58.5 inches outside). With 4 inches of insulation in all walls that gives you interior dimensions of about 91"x 50.5". If you want to ring the outside with a row of bricks to lift the bell one level, your inside dimensions drop to 90"x 49.5".

Dean Hubbard · Post by **Dean Hubbard** » Sun Nov 09, 2003 7:10 pm

charlie holden wrote:Are you talking about using fiber board as your kiln shelf? Unifrax LD board makes a pretty good shelf. I think it comes in 104" x 60" sheets but may be a special order for most distributors.

Yes Charlie,
I've read much in the archives about this and I like the idea of stacking multiple items of insulation to keep the heat away from the bricks. I assume the boards disapate the heat faster than the bricks.
Speaking of the bricks, thanks for the info regarding brick layout. I haven't tried cutting them yet, but was told I could easily cut them with a table saw. I also read about using a saw and router to slot them for element placement.
About the oversize boards being a special order item, I'm trying to avoid that one and locate a large stock size board. Bert said that a company supplies Ultraglas with a large ld board, but I haven't got a response back yet from that company.
I am just amazed with the tests I've done with the float glass, in regards to heat =texture. What type of shelf material gives the least amount of texture? (Shelf primer is the only thing I have used besides compressed dry plaster, which by the way gave me just as much texture and the dry plaster also separated, leaving small cracks for the glass to conform to)
I wasn't aware that I would lose any inside dimension of the bell by stacking a perimeter of bricks to gain height.
Thank You.

elin · Post by **elin** » Mon Nov 10, 2003 2:24 pm

Elin, are the venting chimneys manually opperated, or are they tied into the programmer? One of the kilns I looked at was indeed a FuseStar.

The chimneys are manual. There are also viewing ports on all four sides which can also be un-plugged for crash cooling, if necessary.

I like the mini kiln idea too. Does anyone here post images? You should all show us some pics of your progress as you go.

-elin

Bert Weiss · Post by **Bert Weiss** » Mon Nov 10, 2003 5:47 pm

glazinguy wrote:
charlie holden wrote:Are you talking about using fiber board as your kiln shelf? Unifrax LD board makes a pretty good shelf. I think it comes in 104" x 60" sheets but may be a special order for most distributors.
Yes Charlie,
I've read much in the archives about this and I like the idea of stacking multiple items of insulation to keep the heat away from the bricks. I assume the boards disapate the heat faster than the bricks.

I layer insulation on top of my bricks. This made common sense to me. Recently I fired on a brick floor with a single layer of 1/4" paper on the floor. The result was that glass fused really nice with no visible line between layers when stacked. My kiln at the same schedule would not have fused the layers as cleanly. I see the difference as being the quality of heat being transmitted back from the hot bricks as opposed to the cooler insulated floor. Another reason not to insulate the floor as much would be to facilitate quicker cooling.

Bottom line is that all approaches work, just a bit differently.

Bert Weiss · Post by **Bert Weiss** » Mon Nov 10, 2003 5:53 pm

[quote="glazinguyBert, I couldn't agree any better on this one. At first when I contemplated having a rolling table on a fixed track, (Mainly for sliding it up against a wall while not in use) I considered over building the lower support section of the table with traingulation bracing. (One of the unique situations I have in my shop is, since this was previously a fire station, the shop floors all have a slope for water drainage) I have since scrapped that idea, due to the floor conditions and weight of glass considerations. One thing I will certainly use when leveling the table up during construction, is a rotary lazer level set on a tripod. I used a seven foot door level to level up my pouring table (5' x 10') for laminating glass. I had to get a lazer level and reset all 148 swivel casters after the first attempt at pouring a 60" x 96" piece of laminated glass. (My 7' level didn't show a very slight twist in the table top)

Thank You for all the input folks.

(I'll use the quote feature correctly next time, now that I read how it works)[/quote]

I use a really cool design for leveling. Weld 1" ID bolts to the bottom of your floor supports. Screw in the 1" dia bolts in to each nut. By adjusting the bolts, you can get to level.

Bert Weiss · Post by **Bert Weiss** » Mon Nov 10, 2003 5:54 pm

glazinguy wrote:
elin wrote There are also venting chimneys on the roof of the bell, if you need to crash cool the glass surface.

Elin, are the venting chimneys manually opperated, or are they tied into the programmer? One of the kilns I looked at was indeed a FuseStar.

Bert Weiss wrote Another important aspect of having a non moving floor is the ability to adjust the level at several points around the perimeter and in the middle as well. A level floor surface is the starting point to successful work.

Bert, I couldn't agree any better on this one. At first when I contemplated having a rolling table on a fixed track, (Mainly for sliding it up against a wall while not in use) I considered over building the lower support section of the table with traingulation bracing. (One of the unique situations I have in my shop is, since this was previously a fire station, the shop floors all have a slope for water drainage) I have since scrapped that idea, due to the floor conditions and weight of glass considerations. One thing I will certainly use when leveling the table up during construction, is a rotary lazer level set on a tripod. I used a seven foot door level to level up my pouring table (5' x 10') for laminating glass. I had to get a lazer level and reset all 148 swivel casters after the first attempt at pouring a 60" x 96" piece of laminated glass. (My 7' level didn't show a very slight twist in the table top)

Thank You for all the input folks.
(I'll use the quote feature correctly next time, now that I read how it works)

Dean Hubbard · Post by **Dean Hubbard** » Tue Nov 11, 2003 1:32 am

Bert Weiss wrote:
glazinguy wrote:
elin wrote There are also venting chimneys on the roof of the bell, if you need to crash cool the glass surface.

Elin, are the venting chimneys manually opperated, or are they tied into the programmer? One of the kilns I looked at was indeed a FuseStar.

Something's Funny Here! Too Many Quotes On Top Of Quotes Or Something.
Bert, that's very interesting about that recent firing you did with just 1/4" of insulation on top of the bricks, maybe I've been looking at this the wrong way in regards to heat getting to the bricks.
That mini bell kiln sounds real handy.
Elin, I will post pictures showing construction and completion.

Dean Hubbard · Post by **Dean Hubbard** » Thu Nov 13, 2003 5:10 pm

Hey Kiln Builders,
I don't know if I misinterpreted the information in the archives, but for some reason I lead myself to believe that the best way to configure the insulation for the bell is to install 1" HD board on the sides and top first to the inside of the bell frame, then finish the inside of the bell frame with 2" 8 lb. blanket on the sides and 4" 8 lb blanket (two layers) on the top.
My current sidewall configuration is 3" and the top is 5" (less expanded metal or stainless wrapped exterior)
Are these configurations good, or should I just use blanket? (4" on the sides and 6" on the top)
John @ Duralite has configured a quote for me based on 3" side walls, so I'm hoping I don't need to ask him to recalcuate it for a 4" wall.
I'm finally getting some base prices on the insulation and there would be a bit more waste using the HD board vs. all blanket.
My objective is to have a kiln that heats fast and cools fast also. If by using a combination of blanket and board is correct, it makes sense to me to put the blanket on the finished inside surface of the bell because the blanket wouldn't hold the heat as long as the board. On the otherhand, putting the board on the finished inside surface of the bell and the blanket towards the outward surface would seem to be a better insulating configuration and would make for a more durable exposed material on the inside of the bell, but you would need a way to space the board as not to compress the blanket. Configured in this manner it seems I would have a slower cooling kiln (because the board would hold heat longer than the blanket) and possibly a slower heating kiln. (because it would take more energy to heat the board instead of the blanket)

Have I just over thought myself into a corner here, or does this make sense?

Thanks, Dean

Bert Weiss · Post by **Bert Weiss** » Fri Nov 14, 2003 1:41 am

Dean

You got it sideways. The board goes on the interior because it is a protecting layer. The insulating difference between blanket and board is negligable relative to the difference between brick and fiber.

All blanket kilns work Ok but personally I'd rather have board inside.

The insulation material that I recommend for backup to the board is 1900Âº mineral wool. This is not blanket. I use 2 inches of mineral wool in the wallls and 4" on the roof. I also have a kiln that uses 4" of duraback blanket in the walls and 6" in the roof. The mineral wool is less expensive and a better insulator.

The elements you need are not particluarly dependent on the insulation profile. Watts per cubic foot is a more important calculation, assuming good enough insulation.

charlie holden · Post by **charlie holden** » Fri Nov 14, 2003 12:13 pm

I have what amounts to only blanket as the insulation of the bell of my kiln. It is the same material and the same weight (10 lbs.) interior to exterior, six inches thick. It is over insulated and takes too long to cool. I have found that the interior surface is fine, as nothing ever touches it, so it doesn't shed at all. A lot of people build bells with just two layers of two inch blanket in walls and ceiling.

Bert is right about mineral wool being cheaper and better insulation. It is just messy and weak until you get it installed and covered up. He's also right about the difference between blanket and board being negligible, as far as their insulation value. Neither will hold heat any practical length of time, unlike kiln brick.

Dean Hubbard · Post by **Dean Hubbard** » Fri Nov 14, 2003 2:07 pm

Bert & Charlie,
Thank You, for straightening me out on that one. All of the kilns around here that I've looked at on the inside had blanket, like yours Charlie.
I like the idea of putting the board towards the inside, to give me a more durable finished inside surface.
That changes the waste factor a bit for the better on the board.
I looked a bit into locating a supplier for the mineral wool and found a product called rockwool. Is that the same stuff?

Bert Weiss · Post by **Bert Weiss** » Fri Nov 14, 2003 5:52 pm

I am looking in to a new insulation setup. Skamol 375 vermiculite board backed up with calcium silicate board.

The Skamol board is just a bit lighter weight than HD board and calcium silicate is more stable than mineral wool. Skamol is running some calculations relative to hotface/coldface temps for me. If this works it should significantly reduce the cost and likely simplify construction.

Skamol makes both products. I believe they can be glued up in to modules.

Dean Hubbard · Post by **Dean Hubbard** » Fri Nov 14, 2003 7:20 pm

Bert,
That sounds fantastic; saving in construction and enegy costs and simplified construction. Please keep me posted as to if their test pans out. Are Skamol products easier to obtain as compared to Unifrax?
I live in the "real" Northern California, behind the "Redwood Curtain", so most always I need to drive 6 hrs. south or eight hrs. north to get what I'm after if shipping weights are excessive. (It always cracks me up when people refer to San Francisco as Northern California, I wish they would split this state in two) I really enjoy living in the coastal redwoods, but it does have its setbacks and we have to play by all the rules that the masses south of us create.
Speaking of obtaining materials, I located bentonite locally, but the nearest source for olivene sand is S.F. (I want to try some sand casting)
I'm thinking of starting a new thread on that, but I want to get my hands on some olivene first.

Bert Weiss · Post by **Bert Weiss** » Fri Nov 14, 2003 8:17 pm

Dean Hubbard wrote:Bert,
That sounds fantastic; saving in construction and enegy costs and simplified construction. Please keep me posted as to if their test pans out. Are Skamol products easier to obtain as compared to Unifrax?
I live in the "real" Northern California, behind the "Redwood Curtain", so most always I need to drive 6 hrs. south or eight hrs. north to get what I'm after if shipping weights are excessive. (It always cracks me up when people refer to San Francisco as Northern California, I wish they would split this state in two) I really enjoy living in the coastal redwoods, but it does have its setbacks and we have to play by all the rules that the masses south of us create.
Speaking of obtaining materials, I located bentonite locally, but the nearest source for olivene sand is S.F. (I want to try some sand casting)
I'm thinking of starting a new thread on that, but I want to get my hands on some olivene first.

I'm afraid that Skamol is more difficult to obtain than Unifrax products. Bullseye brings the 600 heavy duty vermiculite board to Portland Oregon. There are various other points in North America where it is shipped to or warehoused in. If the stuff works, we'll worry about how to get it next.

Brad Walker · Post by **Brad Walker** » Fri Nov 14, 2003 8:24 pm

Skamol has two warehouses in the USA, one in Portland, Oregon and one in Charlotte, North Carolina. To buy from them, you need to buy a case, which is anywhere from 72 to 144 boards, depending on the thickness. The material comes from Denmark, so it can be out of stock from time to time. (For example, I have a case on order and have been waiting since September for them to have it in stock.)

Still, I believe the pressed vermiculite material has some real possibilities for kiln building, not to mention mold boxes and kiln shelves.