[240G clay cracking in the glaze firing]

On 3/9/2024 at 12:39 PM, Callie Beller Diesel said:

Hi and welcome! I wish it was under better circumstances.

The pictures are worth a thousand words, and thank you so much for including those!

The fact that the piece is broken so cleanly, and in 2 near-perfect vertical lines all the way through means that this wasn’t specifically your clay, or anything you did during building the piece. It’s a nice dense clay  that probably stuck to the kiln shelf due to the mass and size of the piece, and cracked during cooling. For the next pieces, I’d fire them on some sand/alumina so that the piece has the equivalent of little refractory ball bearings to shift around on. You could also use a waster slab that will shrink at the same rate as the piece, but take the brunt of the force and absorb the crack instead.

If the clay survived the bisque just fine, another possibility is to not fire the piece to full clay maturity. Porosity in the end piece is less of a concern for you than it would be for someone throwing functional ware.

Thanks so much for the feedback very helpful 

[240G clay cracking in the glaze firing]

Hello,

I am creating a large scuplture built in 19" by 11" sections. I am using 240G standard clay and firing at cone 6. I am now aware this clay body is not a good choice for this sculpture but have a deadline in 2 weeks and have to push on through. With the intent to find a better clay body for the next one. With all that being said I just unloaded a glaze kiln to find the piece totally cracked in half. It had no cracks when it came out of the bisque kiln. Do you have any suggestions on ways to avoid this when I remake this piece? I have attached images. 

Thanks,

Sarah 

https://imgur.com/aZ2FpZr

https://imgur.com/mrXXWB4

https://imgur.com/5weAd1i