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Oil drum gas kiln 2.0 and glazes


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#21 Mart

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Posted 20 July 2013 - 04:25 AM

neilestrick, I tested out one of the chimney pipes and after about 1 hour, it cracked and I replaced it with ceramic fiber tube.

I also did not use my home made "flue thingy". Instead, I used 2 thin fire bricks as a support for the bottom shelf and made a half pipe out 25 mm fiber to direct the exhaust out to the brick chimney. 

 

Anyways, the results for our first firing where awesome. Porcelain looks so much better if fired in gas kiln. 

We started out really slowly with a smallest flame possible for about 1 h. Then started to increase the flame slowly. 

After about 9 hours and maybe 9-10 kg of gas the prssure got too low and we decided to stop.

We had additional 11 kg as backup but we decided not to use it. It was probably a mistake because we did not reach cone 7. :(

 

Attached File  IMG_2661-01-sml.jpg   148.23KB   0 downloads

 

Few changes I have to make. 

1) Because the fire bricks, inside the kiln, sank to the floor, the flue opening shrank too. I need to use 2 more thin fire bricks as a "floor" for the flue inside the kiln.

 

2) Lift the kiln higher off the ground so I we have more room to play with the burner distance. 

 

3) Probably spend some more money and buy lower temperature 50 mm 6.5 mm (and put 3 layers) blanket to make the walls thicker. All I need to do is open up the wire cage and wrap it around the existing kiln body. Front part of the kiln has a overlap so it is not a problem. 

 

4) Borrow a kiln pyrometer. Sight and smell will not do it yet :)



#22 Mark C.

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Posted 20 July 2013 - 12:07 PM

As you have found out to reach cone 7 you will need thicker walls. For my cone 11 kilns I use at least 6-to 7 inches of fiber.

 

Now that you have fired the fiber it will be a bit more brittle now so be extra carefull when handling it. 

 

Those glowing walls really show how hot and thin the walls are.

Mark


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#23 Marcia Selsor

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Posted 20 July 2013 - 06:11 PM

If you are going 1260 C I would use the thicker fiber. You'll need that insulation. This is an old portable kiln with 1 inch of fiber  at 1800 F. You can see the buttons through the hot fiber. The kiln is made of hardware fabric  1/4" holes. You can see how hot it is. Go for as much insulation as you can get in there.

 

Marcia

 

 Attached File  Rakusmkiln.jpg   41.85KB   0 downloads



#24 Mart

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Posted 21 July 2013 - 03:53 AM

Marcia, that kiln looks almost transparent :)
I used hardware cloth too for the exterior (I just did not know how it was called in English). Excelent material for something like this.
Looks like I am going to drop another 40 EUR on this an buy a box of 6.5 mm (1/4") low temperature (ceramic fabric 1260ºC (128 kg/m) and wrap 3 layers around the kiln body and reuse my hardware cloth cage.
Or I have to cough up 70€ and get 25 x 610 x 7320 blanket and use that.

PS! Forum administrator, can you please change the thread topic to: "Ceramic fiber / hardware cloth gas kiln 2.0"

#25 Biglou13

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Posted 21 July 2013 - 07:34 AM

Yeah!!!

I'm happy for your progress with kiln!
Caution big brother is watching.
The beige is blinding!!!!!!
The middle of the road is boring

The true sign of intelligence is not knowledge but imagination.
-Albert Einstein

#26 Mart

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Posted 12 August 2013 - 02:10 PM

The saga continues. I got 50 mm fiber blanked and "rebuilt" the kiln over the weekend. Now it has nice 10 cm walls and lid. Waiting for better weather to fire it second time. I have 11 kg of propane and additional ~1 kg leftover from the first firing (perfect for heating up the kiln with a small flame).



#27 Mart

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Posted 05 September 2013 - 02:03 PM

So, I fixed this kiln by:
1) Adding additional 50mm to the wall (final is 100 mm or 10 cm)
2) Placed a broken kiln shelf on the floor to stop the posts (actually 2 think fire bricks) to sink in to the floor and reducing the size of the exit flue diameter.
3) made the burner ports little bit larger. Now those are about 8X8 cm squares.

Ques what, those improvements made a huge difference.
We arrived at cone 7 with no problems, then 8 and 9 too. Finally, cone 10 was starting to go so we stopped.
We spent less than 1/2 the gas we expected and the whole firing lasted about 4.5 h.
I am still waiting for the results because I do not want to open it too early. It has been cooling down for about 6 h and it still over 100 C in there (I stuck a meat thermometer through the wall to measure it) :)
I had my hand in there too but it only felt warm... like in sauna. (BTW, 100 C in sauna is considered "getting warm" around here)

#28 Marcia Selsor

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Posted 05 September 2013 - 05:20 PM

Please post the results. Glad is fired successfully. I hope the glazes look good.
Marcia

#29 Mart

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Posted 06 September 2013 - 08:46 AM

Here are the cones, we used:

 

Attached File  IMG_2676_v1.JPG   110.05KB   0 downloads

 

from left; 7, 8, 9, 10 and only cone from bottom shelf 7

 

Here are some examples

Small porcelain cup with pink hue
clay and porcelain tea cup
Small porcelain bowl with a dot
Small porcelain bowl

 

There are few more images here: http://www.oostuudio...tus-05-09-2013/

 

 






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