Two new bonsai pots

[Ceijay]

Here are two new bonsai pots my fiancé just brought home. One issue that keeps popping up is that the pots like to bow during firing, so if anyone has any tips please share.

I really love the glazes and while I prefer the shape of the first one, the second I think was the most successful and my favorite of the two.

 

[Stan Kengai]

These pots are extremely nice. I love the first pot, excellent shape and beautiful glaze.

I wish I could help on the bowing. There is a kiln crack on the second one, second pic, that was probably caused by the bowing. The pot is still probably usable, but something to watch out for in winter time.

 

[sorce]

I would guess placement in the luln makes for bowing.....

But I'm just going for a real explanation.

If no one here knows....

Chuck Iker would Probly answer an email.

Sorce

 

[sorce]

An excerpt from...
http://www.ikerbonsaipots.com/getting-started-in-ceramics/

I’ve touched on the forming process. The next and very important phase is drying the piece. Clay gives up water slowly and somewhat unevenly. It is important to retard the drying process so that the piece stays relatively the same level of saturation throughout the drying process. If a piece is dried unevenly it will warp and possibly crack either at the drying phase or later in firing. Often pieces are covered with plastic or kept in a drying box to even out and slow down the drying. A piece will usually shrink 5 – 10% during initial drying. This shrinkage is due to the volume of water being subtracted from the volume of the piece. The overall volume is reduced.
-Chuck Iker.

Sorce

@Mellow Mullet
I'm on it!

 

[barrosinc]

Clay has memory, try using a cloth underneath it to move it.
I have had the same difficulty. I started using 15lb or 30lb tar paper to do the molds slab style and remove them when the clay is leather hard. Let me see if I can find the video that helped me a lot.

 

[Ceijay]

@sorce

Thanks for the link but we are already doing all of this. The problem seems to be happening during firing process. I'm not sure if it's happening during the bisque or the high fire but I would assume its a combination of both.

I went back and looked at the first two set of pots and they seem to be much better equability so we will have to figure out what exactly was done differently, although all of the bonsai pot all have some degree of bow in them.

It's a pesky problem for sure.

@barrosinc

This is a great way to construct pieces. It's basically like sewing patterns for clay, although personally I skip the paper part and just free hand them. I do the same thing when I make sewing patterns too.

A lot of the stuff I make are assembled in pieces like this.

 

[barrosinc]

@Ceijay, did you read the part of clay having memory?
if you bend it one way and straighten it later, it will most probably bend in the kiln.
http://www.fireverseceramics.com/clay-memory-and-movement.html

The reason I showed the tar paper is so that you can pick the pieces up without bending them.