First firing in converted gaskiln

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First firing in converted gaskiln

Post  a.muenz on Sat May 25, 2013 12:45 pm

Hi everybody,

this week I had the first stoneware temperature firing in my new old gas kiln.
It is a huge old rectangular electric top loader. I received it as a gift, because it needed a lot of repairs. The electric wiring needed to be replaced and the lid is cracked. Since I always wanted to fire in reduction atmosphere I decided to get rid of all the electric wires and convert it to a propane gas kiln.
It took me a long time to find the burners. It seems that you can't buy them in Germany for a reasonable price. Thanks to the internet I finally contacted a kiln manufacturer in Great Britain. He was very nice and gave me very good advice. I bought two burners a thermocouple and a digital pyrometer for the price of one burner in my country. I drilled holes in the body of the kiln for the burner ports and a bigger opening on the other end for the exit flue. I built a chimney from refractory insulation bricks on the outside of the kiln. Everything was fixed provisionally, because I wanted to test the kiln first. I had already made two bisque firings successfully, so I started the first "serious" firing early in the morning. I started with only one burner and a very low flame to get a steady slow temperature rise. After 8 hours I reached 900 degrees Celsius. The next step was to start with reduction. Unfortunately the reduction slowed the temperature rise drastically. I almost gave up after a couple of hours, when the propane bottles started to freeze. I had to reduce the pressure significantly and that was the trick: the temperature went up again. Cone 7 and 8 were finally completely bent, that was enough for me. After 13 hours I shut off the kiln and let it cool naturally for a day. It was quite an adventure but I am very pleased with the results.



a.muenz
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Pots

Post  lennard on Sat May 25, 2013 6:36 pm

Just went through the pots on your site - love the square ones with the dripping glaze!

Lennard

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Re: First firing in converted gaskiln

Post  prestontolbert on Sun May 26, 2013 5:19 pm

Wow! Good for you for taking initiative. It looks like a very respectable first firing. The pots look great. It looks like your thermocouples are in your burner ports though. That could significantly shorten the life of the thermocouple and give a bad reading. It could affect combustion as well. Do you have any interior shots of the kiln? I love conversion kilns, but yours is the first crossdraft I've seen. Rob Wallace converted an old gas kiln to wood fire, maybe he'll post some shots of that one.

Good luck,
Preston

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Re: First firing in converted gaskiln

Post  a.muenz on Sun May 26, 2013 6:09 pm

Hi Preston,

here is a picture of the inside. It is from the first test bisque firing.

I guess what you see as a thermocouple in the burner port is the safety shut off device and a cable for push button ignition. The thermocouple is in fact located on the upper part on the opposite side of the kiln, where the exit flue is, because I thought, that might be the coldest part of the kiln. It is in fact a bit colder. Cone 8 was completely bent here and melted down on the other side.

I always liked your wood fired pots. In September I will build my own wood fired kiln. It is a design by the australian kiln expert Steve Harrison. It will be a bourry box throat kiln. I am very excited about it. Steve is coming to Germany and we build the kiln as part of a seminar.
http://www.kalkspatz.de/index.php/veranstaltungen/seminare

a.muenz
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Re: First firing in converted gaskiln

Post  prestontolbert on Mon May 27, 2013 3:15 am

Awesome! Sounds like fun. Steve definitely knows his stuff.

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Re: First firing in converted gaskiln

Post  a.muenz on Tue Jun 18, 2013 8:02 am

Hi,

here are some better photos of some of the pots:



oval pot, 55 x 42 x 9 cm

oval pot, 56 x 43,5 x 8 cm

oval pot, 49 x 39 x 5 cm

oval, 38 x 31,5 x 8 cm

oval, 35 x 29 x 7,5 cm 

oval, 36 x 32 x 6 cm

round, 28 x 7 cm

oval, 35 x 31 x 8 cm

a.muenz
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Re: First firing in converted gaskiln

Post  Jake16 on Thu Jun 20, 2013 1:11 am

Do you hand build or have a form for the rectangle and oval ones?

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Re: First firing in converted gaskiln

Post  Stone Monkey on Thu Jun 20, 2013 8:12 am

Excellent results! Thanks for showing. Thats the second person I know that has converted an electric to a gas kiln. Check out Simon Leach's website and You Tube videos and see it in action

Regards

Andy

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Re: First firing in converted gaskiln

Post  a.muenz on Thu Jun 20, 2013 12:14 pm


Do you hand build or have a form for the rectangle and oval ones?



the third one is hand built. All the others are wheel thrown and altered.

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Re: First firing in converted gaskiln

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