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hanee

Propane or wood fired kiln recommendations for low-fire

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I've been a renter and have moved around most of these years so up until now I was never able to consider building a kiln. But after many years of dreaming, we bought land last summer and built a small house and I'm now ready to start planning my studio and kiln.

Fortunately (or unfortunately), depending on your perspective, we are off grid. So electric is off the list, as are any significantly-drawing electric controllers. We also have plenty of wood resources (13.5 acres). I'm a bit of a purist so I'd prefer to do wood firing, but it might be wiser to build an initial propane kiln to get started and migrate towards wood through experimentation.

As for my firing needs. I'm a figure sculptor (my website is at http://haneebirch.org -- though my work has all been on hold for the past 6 months ever since we took the leap on buying land). There's a few requirements that come from that.

1. I only need to bisque fire (cone 06-05). That means my kiln can be designed around only needing to reach those lower temperatures. (Though in the long term I may start trying my hand at slip casting, which woudl technically open up porecelain to me I still think I would tend towards earthenware as I'd rather keep with the lower BTU and the earthier tones)

2. I need some flexibility in size. Long term I may want to try firing some lifesize full figures, but short term, I need to easily be able to fire half-size work (roughly 36" in one dimension and, say, 24 in the other) and busts.

3. I will likely want to have a rather controlled ramp-up and ramp-down though I am comfortable making my bodies more shock proof if needed (I've used raku clay in the past but that was when I did much coarser work than the work I do now). That said, I've never had a sculpture break in a kiln and I have used everything from raku bodies to completely grogless clay, and have fired plenty of things with air pockets and uneven, very thick sections (or solid). I also intend to be exploring base-bodies with heavy straw/planar-shavings/hemp, and firing large solid sections with that mix (which I believe should fire rather well as a ventable but solid core).

So, I'm looking for book recommendations or online resources or personal advice as to good designs to consider. Wood firing, as I said, would be very mcuh ideal.

Cost is a major consideration and I also prefer to use very little technology. Within the rocket mass heater community some people have had success with hand built sraw-clay-vermiculite fireboxes instead of insulated firebrick, ceramic fiberboard, blankets, or cast refractory, so I'd like to explore some eartheir low-tech options but I'm not sure if similar explorations have been done in the ceramics world

Mainly, to start, I will probably just need the quickest, simplest, cheapest cone06 propane-based kiln I can put together but I'd love to be pointed to some dreamier wood-fired options.

Also, I live in a cold winter climate (Penobscot, Maine) -- not sure how reasonable it would be to fire outside and even if I could manage to fire the kiln on a negative 20 degree day, I'd rather not waste the precious heat so designing the kiln for firing indoors (with proper exhaust and make-up air) would be ideal, but not if it made the design much more difficult to acheive.

Personal recommendations? Good books to look into? Websites?

Thanks!

Edited by hanee
typos

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kiln books:

Fred Olsen's "Kiln Book". at https://ceramicartsnetwork.org/shop/the-kiln-book/
Mel Jacobson's "21st Century Kilns"  ebook on amazon, or contact Mel at http://melpots.com/
Steve Mills' "Backyard Kilns"  at: https://stevemillsmudslinger.weebly.com/uploads/1/8/9/8/18980597/backyard_kilns_steve_mills_(1).pdf
Nils Lou's "The art of firing"  

After studying the principles of a combustion kiln, you might consider designing an all fiber kiln, especially if you go the propane route.  Using fiber would allow you to customize the kiln for each sculptural item. 

LT

 

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Thanks for those excellent starting points! I will dig in on them.

Yes, if it was possible to custom build the kiln to the project that would be ideal -- it would probably tie me to propane and technology more, but it would also probably be very fuel efficient and possibly allow me to fire things that couldn't be fired otherwise without a great deal of infrastructure if I had to build a conventional firing box.

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You will need bricks for the firebox area of a wood kiln-fiber is far to fragile to toss wood on or near.The kiln can be fiber which is cheap . My favorite source is high Temp on e-bay.

If wood is what your fuel source is going to be you can start scrounging old fire bricks for floor and firebox.the rest could be fiber but wood will take a toll on it so you will need a thin coating on it.

If its propane its another story.

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The Britt castable refractory catenary arch would be pretty cheap for a wood fired kiln.  You can make your own refractory cement pretty cheap, you just will have to repair it more often than if you use commercial refractory cement.  

https://ceramicartsnetwork.org/daily/clay-tools/ceramic-kilns/how-to-build-a-solid-arch-ceramic-kiln-with-castable-refractory/

I know you'd rather make it with locally sourced stuff, but it would be cheaper than buying brick, and you can make it to fit fairly big pieces.

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11 hours ago, liambesaw said:

The Britt castable refractory catenary arch would be pretty cheap for a wood fired kiln.  You can make your own refractory cement pretty cheap, you just will have to repair it more often than if you use commercial refractory cement.  

https://ceramicartsnetwork.org/daily/clay-tools/ceramic-kilns/how-to-build-a-solid-arch-ceramic-kiln-with-castable-refractory/

I know you'd rather make it with locally sourced stuff, but it would be cheaper than buying brick, and you can make it to fit fairly big pieces.

I'm curious about this idea of using castable refractory material in a wood kiln.

From what little I know castables have  tendency to crack and otherwise breakdown at high temperatures. Add to this the ash and flux floating around in a wood kiln and I wonder how effective a castable would be over time and if the investment is worth it.

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I think the castable would fail sooner than other materials.But it would work for some time.

Wood kilns as noted above are hard on materials.The fiber would also only work in areas of no disturbance and also have a short life.

I feel you would be better looking around for old used fire bricks.

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2 hours ago, C.Banks said:

I'm curious about this idea of using castable refractory material in a wood kiln.

From what little I know castables have  tendency to crack and otherwise breakdown at high temperatures. Add to this the ash and flux floating around in a wood kiln and I wonder how effective a castable would be over time and if the investment is worth it.

Well he said he wants to fire to only cone 06-05.  Would probably not last as long going to cone 10.  The Britt kiln has a layer of kaowool on top of the castable to help limit cracking and spalling from temperature change.  I think it's main purpose is as a soda kiln that doesn't break the bank, but would work in this case too... At least for a while

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21 hours ago, hanee said:

 some dreamier wood-fired options

My wood-fire daydreams circle around “It’s not everyone’s cup of tea…more like an 18ft skiff than a pleasure cruiser, but it’s bloody exciting to fire”........Kevin Grealy

Of course I imagine starting with propane and finishing with wood and some sort of waste oil system - theory is often more shiny than reality.

;)

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Castable will hold up just fine to the vapor and ash of wood firing if you get the right kind. I've seen several of the train style wood kilns that use castable for the throat arch, and I've used castable for the key bricks of several salt/soda kilns.

If you use a wood kiln for low fire work, you'll get ash landing on everything, but it won't melt on its own. If you plan to use glazes, you'll either have to accept a bunch of dry ash sticking to your glazes, or fire everything in saggars. A basic catenary cross draft kiln will work fine, but will create a lot of ash on your pots. If you want to minimize the ash deposits, then a bourry box design would do better, and probably be more efficient.

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