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My Raku Kiln


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#1 neilestrick

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Posted 19 October 2012 - 11:48 AM

There's been a little bit of discussion lately about raku kilns, so I thought I'd contribute with some photos of my kiln. I built this kiln about 6 years with the intent of making the safest raku kiln I could, as well as making it very easy to use. Since I run my own business where I teach a lot of classes, it is very important that I limit my liability and make sure the process is easy and fun. The kiln is built completely of soft brick, with an Alpine-type power burner coming up through the floor. There are several benefits to this design:

1. It's safer. Unlike the fiber-lined drum type kilns that require you to lift the entire body of the kiln off to access the pots, only the person actually pulling the pots from the kiln is exposed to the intense heat.
2. It's safer. There are no fibers to breathe in like the fiber-lined drum type kiln.
3. The pots stay hot. We have put up to a dozen pieces in the kiln at one time, and because we can keep the door closed between pulls, the last pot is still very hot and takes reduction very well. If we need to, we can even keep the burner running very low to keep the heat up while pulling.
4. The bricks hold a lot of heat. It gets to 800 degrees without turning on the burner, which means less fuel needed.

After the first firing, which takes 30-40 minutes, we let the kiln cool to about 500 degrees. Then we place small pieces of soft brick into the kiln, on which the pots sit. Putting the pots directly onto the hot shelf would cause cracking. By getting creative with the posting heights we can get a lot of pots in the kiln. We let them sit for about 2 minutes to warm up a little, then close the door. With the door closed and the bricks radiating heat, the temperature climbs up to about 800 degrees in a couple of minutes. When the temperature stops climbing we light up the burner and take it up to 1850F degrees, which takes 15-20 minutes. Then one person works the door while another person pulls the pots. Once the kiln is empty, we let it cool down again, remove the hot brick pieces and start all over.

For horse hair raku, the pots are only heated to 1250F degrees, which takes about 3 minutes. After pulling them from the kiln and applying the horse hair, we cover them with a can to slow down the cooling, since we usually use a smooth white body that doesn't handle the fast cooling all that well. During last weekend's workshop we fired about 20 horse hair pieces with no cracks!

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#2 Kohaku

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Posted 19 October 2012 - 11:59 AM

I can definitely see lots of advantages here as compared to the pulley system I'm currently using- especially as I contemplate working with larger forms.

Did you weld up the frame yourself?
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#3 neilestrick

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Posted 19 October 2012 - 12:22 PM

I can definitely see lots of advantages here as compared to the pulley system I'm currently using- especially as I contemplate working with larger forms.

Did you weld up the frame yourself?


Yes, I did all the welding, brickwork and built the burner, too. I used a lot of bricks and steel left over from building my gas kiln.
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#4 Cass

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Posted 19 October 2012 - 03:09 PM

nice, i often wish i could grab from the side instead of the top

#5 koreyej

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Posted 20 October 2012 - 02:32 PM

Nice! I have used may raku kilns, but the only brick on I had used was a stacked brick monstrosity. You almost had to lay down to pull pots from it and the second that door came down, the heat just blasted you right in the face. Then we progressed to 55 gallon drum conversions, then the fiber kilns. Yours looks like it's light years better in design. I bet it does keep the heat well AND you are not getting blasted with heat, as well as losing all that heat from removing the top. Great design!

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#6 neilestrick

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Posted 20 October 2012 - 03:01 PM

Nice! I have used may raku kilns, but the only brick on I had used was a stacked brick monstrosity. You almost had to lay down to pull pots from it and the second that door came down, the heat just blasted you right in the face. Then we progressed to 55 gallon drum conversions, then the fiber kilns. Yours looks like it's light years better in design. I bet it does keep the heat well AND you are not getting blasted with heat, as well as losing all that heat from removing the top. Great design!


Thanks! It's basically just a little updraft kiln. We had a front loader in college that was just stacked bricks, kiln shelf top, and a piece of sheet metal covered with fiber for the door. Fired great, but what a mess! So this is my version of that. I think if you're going to be using your kiln in one location (not hauling it around town to workshops), it makes sense to build it solidly and safely. Personally, I think those fiber lined drums should be banned. There are so many safety hazards with them, yet I see them used in schools all the time.
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#7 Benzine

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Posted 20 October 2012 - 03:53 PM


Nice! I have used may raku kilns, but the only brick on I had used was a stacked brick monstrosity. You almost had to lay down to pull pots from it and the second that door came down, the heat just blasted you right in the face. Then we progressed to 55 gallon drum conversions, then the fiber kilns. Yours looks like it's light years better in design. I bet it does keep the heat well AND you are not getting blasted with heat, as well as losing all that heat from removing the top. Great design!


Thanks! It's basically just a little updraft kiln. We had a front loader in college that was just stacked bricks, kiln shelf top, and a piece of sheet metal covered with fiber for the door. Fired great, but what a mess! So this is my version of that. I think if you're going to be using your kiln in one location (not hauling it around town to workshops), it makes sense to build it solidly and safely. Personally, I think those fiber lined drums should be banned. There are so many safety hazards with them, yet I see them used in schools all the time.


I actually just finished building my Raku kiln, though I haven't had a chance to fire it yet.
It is nowhere nearly as fancy as yours, and uses the fiber blanket method.

While I won't argue the blanket can be dangerous, so can pretty much everything else in ceramics. The medium is heated to temperatures that will melt steal in devices with only a couple inches of insulation, the glazes and stains can be toxic and even worse the clay itself can be a hazard. But like everything else in life, if you treat things with the respect they deserve, you can remove almost all of the risk.
This isn't just limited to ceramics either. Artists and art teachers are exposed to so many things that can be downright nasty, photography chemicals, printmaking chemicals, etc. Though as a teacher, I don't see any of that as what will do me in. The stress will get me first.
"Anything worth believing, is worth questioning"

#8 neilestrick

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Posted 20 October 2012 - 04:16 PM

I agree, there are a lot of dangerous things in ceramics and life in general. But the fun of raku seems to overshadow the safety precautions that we would normally take. I have yet to see anyone using a fiber drum raku kiln wear a respirator when they fire, to prevent inhalation of the fibers that are released every time the kiln is moved. I have yet to see every student near the raku kiln wear long sleeves and eye protection. The pots can crack and spit off glowing hot shards. I've seen it happen. And one accidental injury is all it takes to shut down a school art program or a business (in my case). True, injuries are very rare, but they can happen. And as an educator it it my job to make sure that my students understand the safety risks of everything we do in ceramics, and the proper methods of minimizing those risks. Most people that I've seen are not doing a good job of minimizing those risks when raku firing.

Raku is the fastest, easiest method to get dramatic pots, so naturally lots of people want to do it. And naturally people have figured out the easiest, cheapest method of doing it. Which is not, in my opinion, the best or safest way to do it. A perfectly functional cone 10 gas kiln could be built with the same fiber and drum method, but we don't see people doing that. That would be ridiculous, right? We would never build a rinky-dink shim-sham semi durable high fire kiln, so why is it acceptable for raku? Just my thoughts on the matter. Don't mean to rant.Posted Image
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#9 Cass

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Posted 20 October 2012 - 04:50 PM

electric raku for beginners!....just remember to cut the power before you pull, lol

#10 Benzine

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Posted 20 October 2012 - 05:25 PM

I agree, there are a lot of dangerous things in ceramics and life in general. But the fun of raku seems to overshadow the safety precautions that we would normally take. I have yet to see anyone using a fiber drum raku kiln wear a respirator when they fire, to prevent inhalation of the fibers that are released every time the kiln is moved. I have yet to see every student near the raku kiln wear long sleeves and eye protection. The pots can crack and spit off glowing hot shards. I've seen it happen. And one accidental injury is all it takes to shut down a school art program or a business (in my case). True, injuries are very rare, but they can happen. And as an educator it it my job to make sure that my students understand the safety risks of everything we do in ceramics, and the proper methods of minimizing those risks. Most people that I've seen are not doing a good job of minimizing those risks when raku firing.

Raku is the fastest, easiest method to get dramatic pots, so naturally lots of people want to do it. And naturally people have figured out the easiest, cheapest method of doing it. Which is not, in my opinion, the best or safest way to do it. A perfectly functional cone 10 gas kiln could be built with the same fiber and drum method, but we don't see people doing that. That would be ridiculous, right? We would never build a rinky-dink shim-sham semi durable high fire kiln, so why is it acceptable for raku? Just my thoughts on the matter. Don't mean to rant.Posted Image


I would say you are right, in regards to the use of respirators, when actually using the kiln. Luckily, Raku is done primarily outside, in wide open areas, which cuts down on the risk for fiber inhalation.
In regards to other protection, all of my students, will be wearing insulated gloves and eye protection, if they are working around the kiln.
The reason I built my kiln using the fiber and drum method, was for portability. I made it at home, and will transport it to the school to use. The nice kiln you built, would be far too large for me to transport. Maybe, when I get a little more serious about the process, I'll try to find an old sectioned electric kiln, and just convert that. Something like that, I could transport, by disassembling it.

I don't see you as ranting, just trying to keep people safe. Nothing wrong with that, especially considering not everyone thinks of all the risks.
"Anything worth believing, is worth questioning"

#11 Benzine

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Posted 20 October 2012 - 05:26 PM

electric raku for beginners!....just remember to cut the power before you pull, lol


That could be a mistake you only make once.
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#12 JBaymore

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Posted 20 October 2012 - 05:28 PM


electric raku for beginners!....just remember to cut the power before you pull, lol


That could be a mistake you only make once.


Could be a shocking oversight of safety concerns. B)

best,

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#13 Cass

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Posted 20 October 2012 - 05:45 PM

truth be told...i have, in the daze of all-day firing, forgotten to shut it off...don't touch the sides!... like Operation, haha

#14 Benzine

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Posted 20 October 2012 - 07:09 PM

truth be told...i have, in the daze of all-day firing, forgotten to shut it off...don't touch the sides!... like Operation, haha


I can see how that could happen. Not just from routine, or exhaustion, but just from the human brain saying in the background "It's hot, meaning fire, just don't get near the heat and there's nothing to worry about...."

I wonder how well some good insulated gloves would protect a person from 220 volts?
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#15 Marcia Selsor

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Posted 20 October 2012 - 07:12 PM

That is a nice looking raku kiln. I like the wheels. I built mine in a concrete and steel Kiln shed with metal barn doors so I can remove work from the kiln and put the work outside for post firing reduction. Pics are in my gallery. Http://ceramicartsdaily.org/community/index.php?app=gallery&module=images&section=viewimage&img=849
I do make large pieces and my kiln is 27 x 36 interior floor space with min. Ht of 30 inches but can be increased with more courses of bricks. I like being able to pull from all sides in the pulley system. I use to have a front loader and thought the blast of heat was pretty intense. It was a West Coast kiln updraft and about 27 cu. ft. We used it at Montana State University in Billings for years. Fired some large pieces in that. To each their own preference.
I have a smaller oil drum kiln for smaller loads.
My burners are from Marc Ward. The fiber is sprayed with ITC.
I consider the fiber to be pretty stable with the ITC coating.

Marcia

#16 Benzine

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Posted 20 October 2012 - 08:22 PM

ITC Marcia?

I was wondering if there was a coating I could put on the fiber to "seal" it, since I'm done working with it?
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#17 Cass

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Posted 20 October 2012 - 09:53 PM

I wonder how well some good insulated gloves would protect a person from 220 volts?


i use the thick kevlar gloves, like hockey mitts, i doubt it could arc right thru those, i don't want to test it though!

#18 Benzine

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Posted 20 October 2012 - 11:04 PM


I wonder how well some good insulated gloves would protect a person from 220 volts?


i use the thick kevlar gloves, like hockey mitts, i doubt it could arc right thru those, i don't want to test it though!


Like my Dad taught me, when I was a kid, "It aint the volts that kill ya, it's the amps."...........Not that it would be comforting, as electric kilns provide plenty of amps too.
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#19 Marcia Selsor

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Posted 20 October 2012 - 11:13 PM

ITC Marcia?

I was wondering if there was a coating I could put on the fiber to "seal" it, since I'm done working with it?

Feriz recommended it for 8 lb density. You need to squirt water on the fiber first. Lightly. Then spray the ITC lightly.
If it goes on too heavy it will pull the fiber apart from the weight...that is way too heavy.

years ago I use to use a product called Rigidizer made for fiber. I used that on the hinged door on a sprung arch kiln as well as the door on a larger car kiln that I built.

Marcia

#20 justanassembler

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Posted 21 October 2012 - 12:58 AM


I wonder how well some good insulated gloves would protect a person from 220 volts?


i use the thick kevlar gloves, like hockey mitts, i doubt it could arc right thru those, i don't want to test it though!


it absolutely will arc through those, I say this having received a nice 240v jolt from an annealer with a faulty door switch while wearing those kevlar beasts.




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