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Noob Seeks Advice Building Kiln On The Cheap


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#21 Mark C.

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Posted 06 June 2014 - 09:42 AM

As far as thermo couples for gas kilns get one with protection tube like this one.

http://www.ebay.com/...n-/200810725909

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#22 JLowes

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Posted 06 June 2014 - 09:43 AM

If I may suggest some material to investigate, check out Simon Leach's raku kiln videos on YouTube:

http://www.youtube.c...leach raku kiln

 

Also his conversion of an electric kiln:

http://www.youtube.c...kiln conversion

 

For one of his raku kilns, and the electric conversion he uses a cheap commercial propane weed burner.  I fire my propane raku kiln using the same burner, so I know it works, but not as efficiently as a venturi burner, nor with as much control.

 

The pyrometer on Ebay you posted looks like it would work; it has enough range for low and middle firing.  If you follow the link for the Type K probe there is a recommendation for getting a ceramic sleeve for reducing atmospheres.  You would need that also.

 

There is valuable information in the Leach videos, even if you decide to go another route.  Also, it would be helpful to know the characteristics of the refractory brick you have available.  I have seen a gas kiln constructed of house brick with a insulating fire brick base and insulating fiber interior, so many things are possible "in the bush".

 

You have an interesting project.

 

John



#23 neilestrick

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Posted 06 June 2014 - 10:30 AM

The big problem with having a weed burner raku kiln as your only kiln is that bisque firing can be difficult. Whatever you do, you'll need to be able to heat slowly at the low end for the bisque firing.

 

I think the big question here, that hasn't yet been answered, is: What kind of pots do you want to make? Do you want to make glazed functional ware, pots that are strictly decorative, or ceramic sculpture? This is what will determine what type of kiln will best suit your needs.


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#24 Chilly

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Posted 06 June 2014 - 01:27 PM

When you cook a pork roast, you can cook it at 350 degrees for an hour or 275 degrees for 4 hours. Either way you get a roast that's cooked to 170 degrees inside. The heat work is the same even though the temperatures were different. In a kiln, the temperature at which you achieve the heat work will primarily depend on how fast the kiln is heating up. Faster climb equals higher temperature to achieve the heat work.

I like the roast pork analogy.  I usually use baking to explain the difference between transfer, earthenware glaze, bisque and stoneware firings.  Fruit cake, victoria sandwich cake, biscuits, roast potatoes. 

 

It always helps to compare with something that is familiar.  No doubt someone will come up with a "wine/alcohol" analogy............Babs?   ;)


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#25 joff

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Posted 06 June 2014 - 09:03 PM

(Edit- this refers to an earlier post about propane being inefficient, some other stuff came in in between... I should have quoted,)

Hmm... that's not really what I want to hear but I guess it makes sense. Still, I'm gonna call up my appliance repair guy and see what kind of burner he can come up with. It's the simplest, most readily available system to apply and control heat. When I know what I'm doing a bit better I might consider building an electric kiln.

I'm absolutely going to go out to the pottery village when I get a chance to see what they're working with and how they fire it. It's a ways away and I don't have a car so I have to intrigue someone.

I may well make my first attempt a wood fired pit/barrel thing.

I enlisted some drunken help today and got the wheel moved over to my house... it's Flintstone style. I guess that's appropriate for a noob... although I admit the first thing I did was think about where I could attach a motor and drive...

I went out back and tried to find some clay to practice with... long story short it didn't really work. I have found some chunks of very pristine light gray clay out there in the past, but what I ended up with today seemed more like dirt. It wouldn't stick to the wheel.

But the guy who loaned me the wheel is sure there are supplies in San Jose and he's going next week. So we'll see what comes of that.



#26 joff

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Posted 06 June 2014 - 09:13 PM

I think the big question here, that hasn't yet been answered, is: What kind of pots do you want to make? Do you want to make glazed functional ware, pots that are strictly decorative, or ceramic sculpture? This is what will determine what type of kiln will best suit your needs.

Yeah, okay, this is what made me call up my friend and ask if I could borrow the dust gathering wheel... and to be fair I do have some talent as a sculptor but I only ever worked in oven baked acrylics and plaster of paris... but I thought, ######, $200? I could do that.

http://www.ebay.com/...sd=121070808450



#27 joff

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Posted 06 June 2014 - 09:30 PM

So ostensibly I would like to throw useful implements (cups and steins as well as smoking utensils) and add sculpture to them. To sell.

But I'm interested in other iterations of the medium that I'm only tacitly aware of, too.



#28 Benzine

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Posted 06 June 2014 - 10:26 PM

Clay, straight from the ground, needs some processing.  At the very least you are going to have to get rid of the debris, and work it to a good consistency. 

 

Tyler started this great topic, detailing exactly that:

 

http://community.cer...lay/#entry60161

 

Working with clay takes practice, doubly true of the wheel.  It's not something that you can just sit down on, and have everything work out.  People say movies and think, "That looks super easy", and then their hands touch the spinning clay, which apparently creates some type of affliction that makes a person mumble angrily to themselves.

Watch some step by step throwing videos, then practice, practice, practice.  

 

In regards to the pit or barrel firing, both work better if the pots are bisque fired first.  Since that doesn't sound like an option for you, research how people do traditional pit firings.  It usually involves setting the "green" wares on the edge of the fire, and slowly moving them closer, until they are gradually dried and heated.  I have also seen posters here, mention that people will use a normal kitchen-type oven, to heat the wares to around 500 F, and then move them immediately to the fire.  This would serve the same purpose, as putting them on the outer region of the fire, but be more controllable.  


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#29 Babs

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Posted 06 June 2014 - 10:50 PM

 

When you cook a pork roast, you can cook it at 350 degrees for an hour or 275 degrees for 4 hours. Either way you get a roast that's cooked to 170 degrees inside. The heat work is the same even though the temperatures were different. In a kiln, the temperature at which you achieve the heat work will primarily depend on how fast the kiln is heating up. Faster climb equals higher temperature to achieve the heat work.

I like the roast pork analogy.  I usually use baking to explain the difference between transfer, earthenware glaze, bisque and stoneware firings.  Fruit cake, victoria sandwich cake, biscuits, roast potatoes. 

 

It always helps to compare with something that is familiar.  No doubt someone will come up with a "wine/alcohol" analogy............Babs?   ;)

 

I'll put some thought into this, poss some practice too.

The reality of the situation may lend some insight, the sipping of high alcoholic drinks over many hours as opposed to sinking low alcoholic beers over a happy hour?? Or vice versa!  Poss same level but different effects??

Out of practice in pub life, hermit here, so have no great quantity of observations to test this theory.

The low end of the firing in my old gas kiln , one venturi burner, was a difficult thing to control. I used to use the pilot light which could be turned up significantly to edge up teh temp over a few hours but the transition to the main burner often claimed a few victims, esp as the only place for bigger ware was towards the top of the kiln.

Will keep thinking Chilly, off to eat you made me hungry



#30 mudtrust

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Posted 06 June 2014 - 11:30 PM

Hey Joff,

Before building a kiln get some clay and play with it at least.  Work with it for a few months to a year or so.  Make small things and when they're dry throw them in a fire, or just make a stack with 20 or 30 bricks with a fire space underneath and place a few pieces in.  You need entrance for the heat and an exit.  Get use to the clay and how it responds to fire.  I've built 3 kilns for myself and helped build several others.  Have also made cups and saucers and low fired them 'wet' in campfire with about 30% success rate - experiment-get dirty!  



#31 joff

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Posted 02 July 2014 - 10:51 PM

Hey Joff,

Before building a kiln get some clay and play with it at least.  Work with it for a few months to a year or so.  Make small things and when they're dry throw them in a fire, or just make a stack with 20 or 30 bricks with a fire space underneath and place a few pieces in.  You need entrance for the heat and an exit.  Get use to the clay and how it responds to fire.  I've built 3 kilns for myself and helped build several others.  Have also made cups and saucers and low fired them 'wet' in campfire with about 30% success rate - experiment-get dirty!  

This is exactly where I'm at.

I finally got some clay and am messing around with the basics now. I know I have a long way to  go.

I'm going to put off investing a bunch in a kiln until I have a better grasp of the medium. I think I will first build a small wood fired kiln out back since everything is free.

 

I do have a pyrometer on the way which I think is important for understanding what kind of temps I'm achieving so I can juxtapose that info with the results.

I still can't find any glaze in the country. I'm going to be trying to figure out what I can do with the ingredients around, if anybody has any resources for that.

Thanks, Mudtrust, I totally agree.

And thanks to everyone else... I'll be back when I get stuck.



#32 joff

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Posted 02 July 2014 - 11:03 PM

Oh, wait I have a question:

 

So I got this red clay I know nothing about.

 

I understand the basic concept of a cone and 'heat work' as opposed to temp.

 

Considering the fact that the properties of the clay are unknown, would it be logical to make cones out of the clay being used and watch them for (I don't know the nomenclature) a slump?



#33 Mark C.

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Posted 03 July 2014 - 01:37 AM

No thats not what to do.

Better to  fire with cones (known temps) and see what the clay does in kiln say in a shrinkage bar or put or tile form

Clay made into a cone form is just that clay in a cone form.

better to see what temp that clay fires to by seeing it in a pot or slab form.

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#34 joff

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Posted 03 July 2014 - 04:23 AM

No thats not what to do.

Better to  fire with cones (known temps) and see what the clay does in kiln say in a shrinkage bar or put or tile form

Clay made into a cone form is just that clay in a cone form.

better to see what temp that clay fires to by seeing it in a pot or slab form.

Mark

 

 No I know but I don't have access to them.

 

Let me rephrase: If I made a cone out of the clay that I'm working with, would its observation tell me anything of use?

I know this may sound dumb because I can see how cones are used by people with access to them, but I'm thinking that perhaps the original concept of the cone may be related to exactly what I'm talking about. Like you would make a cone out of the clay you were using and be able to make decisions based on its behavior. But I'm just making that up.

 

Okay, BUT- it seems like the whole idea of the cone is to show where we are based on the temp of the clay based on thickness (+ based on melting point of specific clay.).

And then another fundamental point is that what we're doing here is heating sedimentary minerals to the point at which the molecules fuse together, but we don't want to melt it. Right?

 

So it seems like a cone made out of the clay you were working with would begin to melt at its thinnest point at a crucial point in the process of molecular bonding in your actual pottery.

And that the original concept of the cone is perhaps based precisely on this principle. 

But I googled and have no evidence to back that up. And I obviously have no knowledge of the subject.

So I'm gonna try and center another piece of clay. And open it up. I almost got to a little rice bowl last time before it exploded.



#35 High Bridge Pottery

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Posted 03 July 2014 - 05:21 AM

You could use a cone of your clay and watch till it bends but then all your pots would be bending and warping in the kiln too.

 

Have a read through this and it might give you a little more information on what is going on in the kiln and what you might be trying to achieve.

 

https://docs.google....dit?usp=sharing

 

"Think of vitrification as a process that develops in a clay body during firing. We take it far enough to produce the desired strength and color, but not so far that ware begins to warp excessively. Thus each person arbitrarily decides what ‘vitrified’ is for himself and his own circumstances. Some bodies vitrify over a wide range of temperatures, others do so over a very narrow range and thus require close firing control."



#36 JBaymore

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Posted 03 July 2014 - 10:53 AM

Get the book "Pioneer Pottery" by Michael Cardew. For what you are doing .... lots of useful info. (Not the book "Pioneer Potter" ABOUT Michael Cardew.)

 

best,

 

..................john


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#37 Angie Days

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Posted 03 July 2014 - 12:51 PM

Hola, ve este video te va a encantar y no puedes tener nada mas barato y funcional que esto.

 

Todo el proceso en resumen

 

Paso a paso

 






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