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Creating Larger Peices


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#1 Dawn

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Posted 04 July 2010 - 07:49 AM

For the last year I have been trying to make items for the garden that are larger than the household items of my past. I can't seem to get them fired without cracking and breaking up in the kiln. One item is a pagoda. It is about 17" tall after construction. I make it in parts and then fire it together with glaze. The other item is a stepping stone about 1/2" thick and flat.

#2 Chris Campbell

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Posted 04 July 2010 - 09:56 AM

Could you give a little more info?

What clay, how are you building them, how are you joining them, what glaze, when do they break ...
Do they survive bisque then break at higher temp?

Can you add a pix of the pieces?

Chris Campbell
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#3 Marcia Selsor

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Posted 04 July 2010 - 03:49 PM

For the last year I have been trying to make items for the garden that are larger than the household items of my past. I can't seem to get them fired without cracking and breaking up in the kiln. One item is a pagoda. It is about 17" tall after construction. I make it in parts and then fire it together with glaze. The other item is a stepping stone about 1/2" thick and flat.

I have several articles in PMI on building with larger slab pieces than your pagoda and they are built in one piece. Is there are reason you are not building it as one unit?
Check "right angle jig" article,( PMI Jan/Feb 2008) which is also in the book, Ceramics Sculpture; Inspiring Techniques, pp. 87-88. Also tar paper forms article is in Jan/Feb 2009. The right angle jig sounds like it would work well. It describes joining slabs at right angles and standing them up after 2 sides are joined. Then joining the four sides as they stand. Braces are also incorporated inside the corners.
If you are worried about the seams, look into the tar paper forms. That avoids seams on obvious stress points. You might also try building a bird bath PMI Nov. Dec 2002.

When firing the piece make little 1/4" coils to support the piece. ( Vince Pitelka tip) This allows heat around the foot and prevents grabbing the shelf by the piece while it shrinks..

#4 Marcia Selsor

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Posted 07 July 2010 - 08:25 PM

For the last year I have been trying to make items for the garden that are larger than the household items of my past. I can't seem to get them fired without cracking and breaking up in the kiln. One item is a pagoda. It is about 17" tall after construction. I make it in parts and then fire it together with glaze. The other item is a stepping stone about 1/2" thick and flat.


I put some demonstration pics on my American Potters pages. You can see the right angle jig there. There are some corbels shown that were made using that jig. It is a simple construction of plywood and 2 loose boards slipped in to make a cradle to support slabs at a right angle. I think you could use one for your pagoda.




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