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Crusty

Raku Kiln- Highest Cone Temp

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you don't experiment with anything else in it? ever?

 

Nope. It's built for raku. I could maybe get up to cone 6 with it, but I doubt it would go to 10. It's just not insulated well enough for that. I've got my electric kilns for most of what I do. No reason to use it for anything but raku.

 

Raku kilns are made for firing fast to low fire temps. They are generally not insulated well enough for high fire, nor do they typically have the type of control needed for good reduction firing. They are drag racers, made for going fast for a short distance. They are great for what they do, but you wouldn't drive one to get groceries.

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I fire my two raku kilns to 1850 to 1650 or 1275 or 1200 depending on what I am firing. if I want to fire hotter, I'd use a kiln designed for higher temperatures. I built mine for low temperatures and I do experiment with low temperature processes.I have been firing my 2 kilns a lot and I haven't refilled my tanks since last winter. I have a lot of firing left in my tanks.

 

 

Marcia

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what size tanks do you have Marcia? are they modified I any way? we have a empire propane dealer about 1.5 miles from the house. I drive by there every day on my way to work, I been looking at all the different tank sizes ..

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what size tanks do you have Marcia? are they modified I any way? we have a empire propane dealer about 1.5 miles from the house. I drive by there every day on my way to work, I been looking at all the different tank sizes ..

 

The bigger the tank, the less likely it is to freeze up. I fire my raku kiln on 20# grill tanks, but they freeze up when it's cool outside so we don't fire during the cold months. 100# tanks are great, but can be pricey to get filled since most people can't transport them themselves.

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Like Neil, I use a standard twenty pound  grill tank.  

 

To combat the freezing, that comes with firing it in cooler temps, I have a pump sprayer, filled with warm water, that I use to hose down the outside of the tank.  You can also set the tank in a tub of warm water, but I find spraying to be easier, and I don't have to carry that much warm water from the house to the opposite side of the garage, where I fire.  

 

I've successfully fired around 20 F.  Not nearly as cold as some here have fired, but cold enough to be unpleasant.  And one of my pieces got a hairline stress crack.  I believe it was from the thermal shock, but it could have been something else.

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I was thinking of heat rope/panels "I have used them In the past", wrapping the tank with it or even keeping the tank indoors and using a longer feed line.

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Warm water is a better method for keeping it from freezing anyway, as water transfers the heat better to the tank that air.  Air is a good insulator, water is a good conductor.  

 

On top of that, I've even had a tank freeze on warm summer days, when I was pushing the tank more than I should have been.  So if an eighty degree day, didn't prevent freezing, the temperature of the average home, won't either.  Just use the warm water method.

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I have 4 30-pound tanks configured to run in tandem two per burner.I filled them up last November.

I run on 3-4.5 pounds pressure for my firings.I don't have any freezing problems.

I was trying to record the number of firings on one fill up but I have lost count. I refire several times per day when I am not satisfied with some results.

My burners were made by Marc Ward.

 

Marcia

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My set up isn't nearly as fancy as Marcia's.  She looks like a ceramic artist doing a firing.  With my weed burner, hooked to a propane torch, blowing fire into my garbage can kiln, it probably looks like I'm making meth.  And that's just silly, my meth cooking set up looks waaaay different than my Raku kiln...

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I just use two tanks and one burner on my small raku kiln and both burners on the larger Raku kiln.They will be firing a lot in the next three weeks.I have 11 slabs, bunch of pots, ten more tiles and a sculpture drying right now. I hope to fire a bisque this weekend. heavy rains coming tomorrow.I want to squeeze in one more pobvara firing too. Filled the tanks up. $108. Not bad for all those firings.
Marcia.

benzine,
my setup is very practical and very cheap to operate.

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My set up isn't nearly as fancy as Marcia's.  She looks like a ceramic artist doing a firing.  With my weed burner, hooked to a propane torch, blowing fire into my garbage can kiln, it probably looks like I'm making meth.  And that's just silly, my meth cooking set up looks waaaay different than my Raku kiln...

Making meth with a propane torch......can you say BOOM?

 

 

 

Jed

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Making meth with a propane torch......can you say BOOM?

 

 

 

Jed

I never said I was good at it....

 

Marcia, I have no doubt your Raku kiln is cheap to fire.  It would almost have to be, as you seem to be firing it all the time.  You're firing it right now aren't you?....Be honest, as the first step is admitting you have a problem.

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I never said I was good at it....

 

Marcia, I have no doubt your Raku kiln is cheap to fire.  It would almost have to be, as you seem to be firing it all the time.  You're firing it right now aren't you?....Be honest, as the first step is admitting you have a problem.

Jed

 

Benzine, are trying to get me in trouble with Marcia?.....you signed my name to you last message to her. You know the one I'm talking about....lol

 

Jed

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Benzine, are trying to get me in trouble with Marcia?.....you signed my name to you last message to her. You know the one I'm talking about....lol

 

Jed

 

 

All part of my plan.  I don't dare upset Marcia.  I've seen pictures of her heaving large, heavy, burning hot wares out of a kiln, with her hands.  I don't stand a chance...

 

Seriously, I don't like how the quote system, keeps compounding the quotes, so I edit them, to use only the last quote.  I apparently didn't format it quite right.

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Finally sucked all the gas out of the tanks firing the large raku with large foil saggar pieces. Got to 1250 and no more gas. Went to the propane distributor but they had a power outage and closed. Going back this morning to fill up four empty tanks. I actually liked the results of the 1250 temperature. I think going hotter may not have been a great idea. I got some cool colors.

Yes, Benzine and Jed , I was firing. Stinking hot here too. Cold front coming next week with lows at night going down to 60.

No offense taken between potter friends. I have been building raku kilns since 1968 so I have efficiency down. I have a show coming up Nov. 7. I have some pieces using large slabs that have to be mortared and framed. The heat is on.

 

 

Marcia

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Yea, you better keep the kiln glowing... the 7th isnt to far away.. me and Cindy will be in the Bahamas doing some sorkeling..been waiting 6 months for this trip..

 

wow you went almost a year on 120 lbs, thats impressive.. ill check the Ward burner out..

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One thing that hasn't really been separated out in this discussion is the difference  between pyro cone  and  temperature.     It is comparatively simple to reach a temperature  in the yellow white range in a propane  furnace.  That is mostly a function of BTU in and volume.  Cone is a  function time at temperature  or  heat work.  I know that most readers of this forum make that assumption know this but for the casual or newer member it would be well to be more explicit.

 

When people say that running cone 6 in a Raku kiln would me unreasonably expensive in terms of fuel I take that as recognizably true. If  one assumes a Small Orton cone  this gives a temperature of 1255C with a temperature rise rate of 300 C/hr.  

 

Cone 04 on the other hand seems more achievable as a small Orton cone is 1098C @ 300 C/hr. Personal experience tells me that the time an effort to go from and orangish yellow   to yellow white heat  is a lot.

 

All this is in aid off is the point that Raku  is more Art and Craft  and  Experience than many other parts of custom made ceramics.

 

Lockley

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I think it may also be important to consider kiln size and insulation and gas regulators when comparing both BTU consumption and cones versus temperature. I am doing alternative firings in foil sag gars to ^019 and ceramic sag gars to ^08, as well as obvara to ^08. I am also firing to ^06 or 1850 for raku. My kilns have 1" 8# density fiber treated with ITC.  My large raku kiln is about 20 cu. ft. and my small one is about 6 cu. ft.

The BTU rate of consumption increases exponentially as the temperature rises. The rate of fuel consumption to maintain a temperature is not the same as increasing the temperature. That is why going from ^6 to ^10 can consume twice as much fuel.

 

 

Marcia

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Seriously, I don't like how the quote system, keeps compounding the quotes, so I edit them, to use only the last quote.  I apparently didn't format it quite right.

Benzine, are you using the WYSIWYG editor? Try clicking the little light-switch in the upper-left corner of the editor... that switches to plain-text mode and you can manage the quotes much more easily, because it turns the quotes into text begin/end markers.

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WYSIWYG editor? Try clicking the little light-switch in the upper-left corner of the editor... that switches to plain-text mode and you can manage the quotes much more easily, because it turns the quotes into text begin/end markers.

Ohhh wowww. That makes life so much easier. But why doesn't that little button (are you sure it's a light-switch?) (yes it is, I just enlarged the screen-view) have a label to say what it is when you hover over it?

 

Thanks Carl

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