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  #1  
Old 08-02-2005, 04:55 AM
seru seru is offline
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Arrow Armatures in clay

In high school, my art teacher always urged me that I take out the armatures (usually aluminum or galvanized wire) for my clay pieces. Me being fresh on the sculpture scene, I never knew exactly why. Is there a problem leaving an armature in the piece during kilning or other problems? I always assumed it would ruin the kiln or something.

Also what is a good armature to use in clay in general. I usually use like between 13-16 gauge aluminum wire. I just got out of high school and wanted to pursue sculpting as a hobby. My pieces, as of yet, usually range in size depending on subject matter but never get too much bigger than my chest and never smaller than my hand. thanks -- Seru
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  #2  
Old 08-02-2005, 08:16 AM
GaryR52 GaryR52 is offline
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Re: Armatures in clay

Depending upon the material(s) the armature is made of, it could damage the sculpture if left inside during firing, particularly if it's a metal with a relatively low melting point, such as aluminum armature wire. If it's something like wood or some other combustible material, it will usually burn out and this could also damage a sculpture if the resulting gases don't have a way to escape the piece during firing. Also, if your clay sculpture is built solid (not hollow) or very thickly, it will tend to explode in the kiln, anyway, armature or not. I learned this the hard way, myself, in college. Took out a few other students' work in the process, too.

Usually, for sculpture done in clay with an armature that's to be left inside, we're talking plasticine or some other non-firing clay that is going to serve as a pattern for a mold that will be used to cast metal, such as bronze. Ceramic sculptors (correct me if I'm wrong) will usually construct their work hollow and with wall thicknesses that don't require the support of an armature. You can do this, to an extent, by working patiently and not adding more clay until what you've already done is leather hard, building the walls gradually, so they don't collapse. But, of course, it will vary with the form you're creating, as well as its size. This is one reason why ceramic sculpture has never particularly attracted me as a medium of expression; too delicate and unforgiving.

Gary
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  #3  
Old 08-02-2005, 11:08 PM
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fritchie fritchie is offline
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Re: Armatures in clay

seru - Your art teacher and Gary R52 both have given the best (and really, the only correct) advice. Some of my art school classes were about 40 years ago, and some were about 15 years ago, but all my instructors said the same thing.

If you have a metal armature in the piece, chances are the armature will shatter your clay when you fire it, because the water in the clay is driven out very quickly, and the clay shrinks quite a bit before really firing. The metal canít shrink, so it generally will split the clay. As Gary said, other pieces in the kiln may be damaged also. You might use an armature that would burn out, such as bits of wood and string, but the gases produced by burning could cause similar problems, and also damage the kiln.

People who fire clay pieces generally build them with no armature, and they also build them hollow, and with fairly thin walls, for just the reasons Gary gave. Itís really best to think along those lines - no armature, and with no area where the clay is more than Ĺ inch to 1 inch thick, depending on the piece.

If you are using some kind of community or school kiln, theyíll probably insist that you follow those rules, and Iím sure they will be glad to help you plan your work.

Good luck!
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  #4  
Old 08-11-2005, 02:10 PM
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Re: Armatures in clay

All good advice, but I offer another angle.
I've made several hundred life size heads in ceramic and this method has never resulted in explosions, breaks, and hardly even any hairline surface cracks. I use a simple pipe with a big wad of newspaper at the top as the armature and build the clay up around that, then slide the head straight up, off the pipe. let it dry and let the paper burn out in the kiln. Some walls have been over 6 inches thick. The catch is, the clay must contain grog, it must be steam dried instead of air dried, and it must be fired low and slow.
Small figures, I use the clay itself as an armature (hardened) and fire them solid.
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Old 08-11-2005, 05:11 PM
GaryR52 GaryR52 is offline
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Re: Armatures in clay

Well, you wouldn't experience any exploding or cracking unless the walls of the piece are too thick, or if you left the pipe in place. Newspaper burns out and does no harm, so there really isn't anything different about what you're doing; it's the same thing I was suggesting; i.e., don't leave a metal armature inside a clay sculpture during firing.

Gary
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Old 08-11-2005, 10:31 PM
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Re: Armatures in clay

? I think the only point I offered was that under certain conditions, the clay can be successfully fired thick. Unless 6 inches is not considered thick that is. Of course you can't put a metal armature in a kiln. Well, you can, but bad things are sure to happen if you do.
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Old 08-12-2005, 12:01 AM
GaryR52 GaryR52 is offline
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Re: Armatures in clay

Sorry, Buster, I assumed you had read the entire thread and knew that the original question was whether a wire armature could be left inside the clay during firing. That was the issue we were discussing. What got my attention, in your first post, was your statement, "All good advice, but I offer another angle." I read the post, but you didn't say anything I hadn't already addressed, so I was wondering what other angle you meant.

Gary
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  #8  
Old 08-12-2005, 06:35 PM
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Re: Armatures in clay

Sorry if I wasnít clear. I did indeed read the entire thread, but didn't feel the need to address the original question since it had already been answered. The different angle I was referring to was addressing the additional statements made about the clay wall thickness since it was repeated several times that they should be thin, including in your reply to my original statement, which I had assumed you read. All I wanted to add was that in my many years of firing ceramic pieces thick and/or solid, I can say that it is possible. Sorry if my input here was perceived as valueless.
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Old 08-12-2005, 09:16 PM
GaryR52 GaryR52 is offline
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Re: Armatures in clay

Ah, I see. My apologies, then. Yes, with grog added, you could make the walls any thickness you wanted to and, no, your post was not not "perceived as valueless," it only seemed to me, at the time, to repeat what had already been said. That was my mistake, though.

Gary

Last edited by GaryR52 : 08-12-2005 at 09:19 PM.
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  #10  
Old 08-12-2005, 10:03 PM
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fritchie fritchie is offline
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Re: Armatures in clay; Steam drying???

Buster - Valuable insights, based on many years' experience. In my early classes, grog always recommended for clay to be fired, but I never went in that direction (firing). I am surprised you can get away with such thick walls.

Also, Iíve never heard of steam drying. What is that? Obviously, from your reply, it has a great advantage with this sort of work.
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  #11  
Old 08-13-2005, 01:12 AM
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Re: Armatures in clay

No Problem Gary, I was just confused by your responses.

Fritchie, I guess steam drying really isnít an accurate description. Sweating them dry is probably more fitting a term. As you know, when ceramic clay dries, it shrinks. If you set a piece on a shelf and let it air dry at room temperature and the piece is very thick, the outside dries and shrinks much faster than the inside and the piece cracks.

By sweating/steaming it dry, I just mean that you can dry the piece in a hot (170 degree), moist, confined, sealed (but not completely airtight), controlled environment and the piece will sweat profusely until all the water has evaporated and the piece is left bone dry, all the way through. Because the water canít escape very fast, the air stays very wet and the outside and inside of the clay dries and shrinks at the same rate, therefore no cracking. There's no shortage of heat here in Arizona, so this works pretty good here without having to waste electricity or gas. They dry surprisingly fast too.
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  #12  
Old 08-13-2005, 06:23 AM
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bluedogshuz bluedogshuz is offline
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Re: Armatures in clay

My 2cents... I took a class years ago with a sculptor that had a heavy grog mixed clay. She would air dry the pieces, and then I think she did two firings or fired over a long period of time. Grog clay is ok if you aren't looking for fine detail, if you are it simply isn't the right process. My figures were approx 4" thick with a small hole underneath to allow for the process. I never had a blowup.
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Old 08-13-2005, 12:47 PM
GaryR52 GaryR52 is offline
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Re: Armatures in clay

As I recall, from several books I read on ceramic sculpture, the long firing process you're describing, Blue is the same thing Heidi's calling "steaming." My recollection of the process is that you turn the kiln on at a low heat, leave the kiln partially open to vent the steam, and leave it that way for a day or more, allowing the clay to dry slowly and evenly. I think this is what Heidi meant by "steam drying." If not, I'm sure she'll slap me silly.

Gary
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  #14  
Old 08-13-2005, 01:02 PM
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Re: Armatures in clay

That's true Gary (no slapping needed ), you can force the last bit of moisture out of the piece by placing it in the kiln on low for a day or two. By sweating, or steaming it dry though, I meant the initial drying when the piece is still very wet. Usually, I'll put the piece on a rack (because water will pool at the bottom) and put it in an oven roasting bag, or large garbage bag. Poke several holes in the bag for the moisture to escape, and put the piece/bag in a hot box or in the direct sun for about a week.

Blue, that's true that a coarse grog clay is hard to get a nice detailed surface with. I use a fine grog clay and am careful not to overwork the surface with water, which would expose the grog. A friend showed me a technique he uses where he models the piece with a fine grog clay, and then paints layers of slip on the surface to get it baby smoothe. Here is a crop of one of his pieces.
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Last edited by Buster : 08-13-2005 at 01:33 PM.
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