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Firing a Piece too large for an kiln


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#1 Frankiegirl

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Posted 22 April 2013 - 08:16 AM

Last year I made a large piece that I miscalculated the shrink rate on and now it doesn't fit in the kiln easily. That is part of the reason that it has been sitting around for year in my studio. I bisque fired it on a slant (it is supposed to lay flat like a platter) with no issues, and now I am not sure what to do for the glaze. I think I can slant it nicely for a glaze firing but I am afraid to try it. I am concerned that it can be too close or touch some of the kiln elements as it shrinks in the glaze firing. I also didn't want to use posts to prop it up because I thought they might shift as it fires. Do I have a large bisque fired piece of junk? Any ideas are welcome.



#2 Benzine

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Posted 22 April 2013 - 08:37 AM

What Cone will you be glazing at?

As I see it, you have a couple options. One, fire it in your kiln, as you planned, and hope the glaze doesn't flow, and drip all over. Two, find someone close by, with a larger kiln, they'll let you borrow. Three, potentially build a temporary kiln out of kiln brick, or ceramic fiber blanket, and fire it that way. I won't pretend to be an expert on the last method, but I do know that ceramicists use the method, for very large pieces. There are plenty of other posters here, who know more.
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#3 Frankiegirl

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Posted 23 April 2013 - 07:01 AM

Thanks for the ideas! I am firing at cone 6 ox. I don't think building a kiln around this piece would be cost or time effective for me, though that does seem like a good idea. Ceramic wool and burners are pricy for just one piece. Not sure if I would ask people to use their kiln even if I knew someone with a large enough one.

Drippy glaze is what I am afraid of. That, and broken pieces of pottery with drippy glaze attached. I think as this thing shrinks, it has the potential to slide down the kiln wall and break. That could be a mess.

This is purely a decorative piece so I am only concerned about look. I am wondering if I can just paint it and have done with the whole thing. Don't have much experience with paint on bisque. Wonder if that would be another disaster.

#4 Diane Puckett

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Posted 23 April 2013 - 07:17 AM

Thanks for the ideas! I am firing at cone 6 ox. I don't think building a kiln around this piece would be cost or time effective for me, though that does seem like a good idea. Ceramic wool and burners are pricy for just one piece. Not sure if I would ask people to use their kiln even if I knew someone with a large enough one.

Drippy glaze is what I am afraid of. That, and broken pieces of pottery with drippy glaze attached. I think as this thing shrinks, it has the potential to slide down the kiln wall and break. That could be a mess.

This is purely a decorative piece so I am only concerned about look. I am wondering if I can just paint it and have done with the whole thing. Don't have much experience with paint on bisque. Wonder if that would be another disaster.


I know a potter who makes sculptural pieces and paints on bisque. She uses acrylic hobby paints and then sprays on Clear Coat after she is finished painting. Rather than Clear Coat I have used spray lacquer, which is great because it dries instantly. You can just continue spraying until you get the look you want. Try it on something small to see if it work for you.
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#5 macdoodle

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Posted 23 April 2013 - 07:44 AM

Sounds like a good reason to have a bonfire with friends .

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#6 AtomicAxe

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Posted 23 April 2013 - 10:14 AM


Thanks for the ideas! I am firing at cone 6 ox. I don't think building a kiln around this piece would be cost or time effective for me, though that does seem like a good idea. Ceramic wool and burners are pricy for just one piece. Not sure if I would ask people to use their kiln even if I knew someone with a large enough one.

Drippy glaze is what I am afraid of. That, and broken pieces of pottery with drippy glaze attached. I think as this thing shrinks, it has the potential to slide down the kiln wall and break. That could be a mess.

This is purely a decorative piece so I am only concerned about look. I am wondering if I can just paint it and have done with the whole thing. Don't have much experience with paint on bisque. Wonder if that would be another disaster.


I know a potter who makes sculptural pieces and paints on bisque. She uses acrylic hobby paints and then sprays on Clear Coat after she is finished painting. Rather than Clear Coat I have used spray lacquer, which is great because it dries instantly. You can just continue spraying until you get the look you want. Try it on something small to see if it work for you.


There is one ceramic artist who uses oil paints to do an oil patina that looks like amazing ... can't help with the name, sorry. there is also other artists that use anything from oils to water colors to finish a piece. I myself have some pieces I paint and not glaze, but I high fire my pieces first as the open clay body is not ideal for paints like automotive enamels ... and if I use something like acrylics ... i like my paint to be blendable and not dry almost instantly.

One process you might find almost perfect for hand painting clay (especially textured pieces) is dry brushing. it is easy and works extremely well. also, there are tons of finishing options so check your clear coats and/or appropriate varnishes for matt, semi-gloss and gloss surfaces post painting ... I myself look for satin finishes but that is because I like the way light hits that finish.

#7 perkolator

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Posted 23 April 2013 - 12:01 PM

building a kiln around the piece is not practical for something like this. if you built a huge sculpture and it needed to be fired on-site, then yes - but for a small slab built form i wouldn't even consider it.
approximately how much too large is the piece you need to fire? if you say you made it thinking it would fit, I'd guess it's fairly close to the width of your kiln, and that it doesn't sit at too steep of an angle in the kiln when propped up (like less than 45* angle). since the piece is already bisk fired, it's already shrunk a fair amount and concerns of post/stilts shifting shouldn't really be an issue at all. if you're concerned with glaze running off when fired on a slant, i wouldn't let this be a concern either - people fire very tall vertical pieces all the time and those glazes would technically shift more since they're on a vertical surface. using a more stable glaze should be a simple remedy.

personally, i would just try to fire it with glaze before compromising and using paint. just make sure to take some extra precautions in the kiln - use hard brick supporting a shelf on a slant, for a nice sturdy base to support the platter. I would NOT fire this piece unsupported and just lean it against the wall of the kiln - it will likely warp and bow in the center. prop up the bottom contact point of the piece with bar stilts sitting in a bed of silica or alumina to catch any possible runs. if for whatever reason the piece fails (which I don't really see happening), then oh bummer you get to build another piece and learn more. 2nd version will probably be better built and go faster since you know much more about it.


#8 neilestrick

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Posted 23 April 2013 - 02:10 PM

Is there anyone in your area with a larger kiln you could pay to fire it for you?
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#9 Pres

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Posted 23 April 2013 - 04:08 PM

Last year I made a large piece that I miscalculated the shrink rate on and now it doesn't fit in the kiln easily. That is part of the reason that it has been sitting around for year in my studio. I bisque fired it on a slant (it is supposed to lay flat like a platter) with no issues, and now I am not sure what to do for the glaze. I think I can slant it nicely for a glaze firing but I am afraid to try it. I am concerned that it can be too close or touch some of the kiln elements as it shrinks in the glaze firing. I also didn't want to use posts to prop it up because I thought they might shift as it fires. Do I have a large bisque fired piece of junk? Any ideas are welcome.



Where in PA are you, anywhere near Altoona? How large is the piece?

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#10 minspargal

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Posted 25 April 2013 - 08:52 AM

I think painting it is a good option, both acrylic and oil paints work on bisque. One of the hobby mega stores used to sell a paints that made the painted piece look like weathered copper. It even fooled my professor in college who wondered why i was bring a metal sculpture to class.

#11 Frankiegirl

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Posted 25 April 2013 - 02:58 PM

The piece is only slightly larger than my kiln can accommodate. It would be less than a 45% angle in my larger kiln. I made the piece thinking it would shrink most of the shrink percentage from wet to bisque. That wasn't the case. What I failed to consider was the fact that this clay shrinks a fair amount in glaze firing. It was a dumb mistake but I guess it did teach me not to be so greedy...

I don't know anyone with a wider kiln. I need something larger than the 23" width that I have. I am in Eastern PA- far from Altoona. Perhaps I can check one of the schools art departments. I really would prefer glaze to paint. I think it can be really special with glaze as I intended.

If it doesn't work out, I can always paint it.Posted Image

#12 neilestrick

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Posted 25 April 2013 - 03:51 PM

Someone in the area is bound to have a 28" kiln. Start calling!
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#13 SmartsyArtsy

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Posted 30 April 2013 - 11:16 PM

While I cringe about painting, I just found a happy medium with a piece that I couldn't stand up in the kiln for glaze firing. I bisqued it with an ennoble and tonight I sprayed krypton clear on it. Looks pretty good. This is the main body of a large birdhouse, and the other pieces have been glazed and fired, and will be attached tomorrow.

So, that may be another option to get color on it-- make up some engobes and retire bisque temp.




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