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Raku Kilns


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#21 Kiln-man

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Posted 13 September 2010 - 04:30 PM

What are you wanting to do. Studio work or travel.
The kilns will do the same thing. But there is a learning curve on all kilns.
An old ceramic kiln is the easiest to convert over to gas fire.
Sources are craiglist, ebay, auctins by local school districts or old potters getting or already out of the business.
You can use an electric kiln for raku but it is hard on the elements.
Gas firing appears to be a better method, whether its natural gas, LP or Butane.
Wood will work but it has high labor cost.

Also where will you be firing the kiln?
Do you have a area where the fire will not spread?
Got water close by if there is a problem?
Is smoke going to be an issue. Don't want neighbors callling fire department.
One of the ways to ruin a raku party is having the fire department show up.

There are numerous book on raku firing you might want to read.

MOST OF ALL DON'T TRY THIS WITHOUT SOME HELP BY ANOTHER EXPERIENCE RAKU PERSON.
THERE IS A LOT OF SMALL THINGS THAT CAN HURT YOU.

#22 Potterstu

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Posted 13 September 2010 - 06:00 PM

Back in the mid 60's and early '70's we had very little knowlegde of Raku techniques, or safety. I remember gloves made of pure 100% asbestos!
As hippies on Venice beach we found a pile of old red brick, fashioned a very crude kiln, attached a garden hose to a gas meter, cut off the end of a burner from a discarded hot water heater and used a couple of childrens crutches as tongs. I still have a few of pieces from that p[ile of brick.

At a workshop in Colorado in 1972, we got a box of some material (an early form of Fiber Frax, I think) from Corning. They were testing it for insulation in things such as space suits. The challenge was to use it in any way we wished, then report back to Corning. We used it to patch cracks in kilns, we mixed it in clay and finally using the last few yards, we lined the carboard box it came in then built fire brick platform and proceeded to fire with our carboard kiln! It lasted all day and into the night, until a pair of tongs tore the insulation and we watched our kiln go up in flames. It was GREAT!

We now fire with a sophisticated motorized kiln, and the results are just as good.

Raku: It's for the pyromaniac in you.

Keep potting,

Stuart

#23 Marcia Selsor

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Posted 14 September 2010 - 08:53 AM

We've come a long way from those hippie days. I remember getting sent home from a design class because the kerosene leaked on me during a raku firing earlier in the class day. Now we are all responsible adults and know better.
Marcia



#24 Keramic

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Posted 14 September 2010 - 10:54 AM


what is the differences in raku kilns? portable vs. non portable? will your results be the same in any raku kiln?


I once built the classic updraft, wood-fired raku kiln, but basically used it to fire burnished work in. The local clay was extremely fine particle 300 million year old earthenware clay, all you had to do was rub it with a soft cloth to get a burnished surface, the kiln was made out of brick covered with a layer of clay, and I had construction crews dump wood off at the house. The pictures are in the Leach book as well as the Cardew book, if you don't know the titles, google the authors with the word "pottery"
h a n s e n




As a newbie I am pleased to see that Bernard Leach has so many mentions. I met him whilst at Art College and have visited his pottery at St. Ives, Cornwall, UK. T%he fireplace , where he and Hamada had so many discussions, is still there as in his book. Look forward to perhaps getting verbally involved.
on here.

#25 Deb Evans

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Posted 14 September 2010 - 11:32 PM

portability is in the eyes of the beholder. As an raku artist in residence in Syracuse NY in the 70's , I use to set up cinder block base, 100 gal propane tank, hard brick floor, kiln shelf, solf bricks for walls and old paragon lid for top. only took an hr or so to set up..... I love NASA - fiberfrax makes a great walls and lid for personal use, prefer brick for class use. Fav raku kiln of all time was a steel legged asbestose box w/ duel cross burners , just for mugs and sm bowls, preheated on roof and fired in 15 min. I 've seen hudge kilns for 1 piece ; lift hood and reduce on the pad; pizza oven design w/ 2 burners for large slabs; wood fired / car kilns for class use.
In other words , raku kilns are boxes of fire. I agree w/ all the post folks, really depends on what forms you want to fire and circumstances of studio. Use Steve b's raku book and ward web site and you're set.

#26 Mark Ayers

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Posted 15 September 2010 - 02:45 PM

when I started teaching in Montana in 1975, there was a brick wood-fired raku kiln that took 8 hours per cycle. I built one using a barrel, fired with wood that could fired ...after several loads, in 3.5 minutes. It is featured in the Steven Branfman Raku Book, a Practical Approach, 2nd. ed. and it is my design. Point is, American raku is a fast firing. You can use less fuel if you insulate well and have a good efficient fuel consumption.
Marcia



I just found this forum and glad I did.

Marcia you state that your later subsequent firings only took 3.5 minutes to reach temp. Am I reading that right?

I take almost the same time in second,3rd,4th etc firings as I do in my first.

I have a 23X36 4 section ^10 two burner gas kiln. I modified the jets ( opened them up) to accommodate propane. And only run 3 rings but have ran it for a day with just 2 rings in and did not like the process so I went back to 3 rings. I have not made anything tall enough to run all 4 rings in a Raku firing and have never ran a ^10 reduction firing with it.

I usually take around an hour on the first firing then set my new work in the kiln and let it soak in the 600- 700 deg F kiln. After 10 minutes or so I light one of my two burners till I get to around 1000 deg F then take my time till I get to 1850-1900 then shut off the gas and pull the pieces.

I have played with reduction in the kiln as I am firing and know that slows things down also. I put it into reduction around 1500 deg F and hold it there until I reach my desired temp. The last few minutes I let it clear out just a bit by pulling back my baffle plate on the top. I only do this when working with a glaze that has some copper in it not in any of the crackle glaze I have used.


Prior to running my own kiln I had only been around one raku firing and so I have a lot to learn as is the case when one is new to anything.

I have cracked some of my work and I thought it was from to quick of a ramp up to max heat. I think the other reason is some of my work is still too think, new potter style thick.

I am open to anyone's thoughts on my processes and techniques in my firings.



Thanks everyone and again really glad I found this forum.

Mark
Sacramento Calif

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#27 Marcia Selsor

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Posted 15 September 2010 - 02:56 PM

<br>

<br>when I started teaching in Montana in 1975, there was a brick wood-fired raku kiln that took 8 hours per cycle. I built one using a barrel, fired with wood that could fired ...after several loads, in 3.5 minutes. It is featured in the Steven Branfman Raku Book, a Practical Approach, 2nd. ed. and it is my design. Point is, American raku is a fast firing. You can use less fuel if you insulate well and have a good efficient fuel consumption.<br>

<br><br><br>I just found this forum and glad I did.<br><br>Marcia you state that your later subsequent firings only took 3.5 minutes to reach temp. Am I reading that right? <br><br>I take almost the same time in second,3rd,4th etc firings as I do in my first.<br><br>I have a 23X36 4 section ^10 two burner gas kiln. I modified the jets ( opened them up) to accommodate propane. And only run 3 rings but have ran it for a day with just 2 rings in and did not like the process so I went back to 3 rings. I have not made anything tall enough to run all 4 rings in a Raku firing and have never ran a ^10 reduction firing with it.<br><br>I usually take around an hour on the first firing then set my new work in the kiln and let it soak in the 600- 700 deg F kiln. After 10 minutes or so I light one of my two burners till I get to around 1000 deg F then take my time till I get to 1850-1900 then shut off the gas and pull the pieces.<br><br>I have played with reduction in the kiln as I am firing and know that slows things down also. I put it into reduction around 1500 deg F and hold it there until I reach my desired temp. The last few minutes I let it clear out just a bit by pulling back my baffle plate on the top. I only do this when working with a glaze that has some copper in it not in any of the crackle glaze I have used.<br><br><br>Prior to running my own kiln I had only been around one raku firing and so I have a lot to learn as is the case when one is new to anything. <br><br>I have cracked some of my work and I thought it was from to quick of a ramp up to max heat. I think the other reason is some of my work is still too think, new potter style thick. <br><br>I am open to anyone's thoughts on my processes and techniques in my firings.<br><br><br><br>Thanks everyone and again really glad I found this forum. <br><br>Mark<br>Sacramento Calif<br>

<br>The 3.5 minute firing was with wood.This is after a long day of firing...the later loads hit temperature with just a few pieces on wood stoked. There was a hefty bed of coals. Pots were preheated on the hot bricks of the meter long fire box. We clocked it. It was amazing. After stoking the flame would roar out of the top of the oil drum barrel which sat on top of a 20-24 inch beehive of bricks. The fire box was about a meter long and was fed by the westerly breeze. e fired lots of beginners student work. Didn't lose many pots.&nbsp;&nbsp;I used scrap 2 x 4 from a truss factory. We split the 2 x 4s into small pieces. They burn faster and released btus faster.<br>Marcia

#28 Mark Ayers

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Posted 15 September 2010 - 03:31 PM

Marcia

That is amazing that you could get the pots to temp that quickly. I have always thought you needed to go slower even if the kiln was hot. I will try it. Usually my kiln sits at 6-700 deg F after I pull every thing out. I have pre-heated my pieces on top buy the square vent hole. However I have seen what looked like burnt glaze and thought it was because the piece was too close to the flame coming out of the kiln.
Lots to learn, and that is part of the fun

Mark
PS thanks for the quick reply




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