I've been working with IMCO Stoneware 1-C for a few months now, loving it as a mid-firing stoneware (texture and color).
However, when I fire it to the advertised maturation temperature of ^6, I see a good bit of bloating.
At ^5 everything seems fine.
To cover the normal basic troubleshooting, I've noticed bloating between ^5 and ^6 considering:
- Same clay batch and even BAG
- Same bisque firing
- No carbon coring noticeable when broken open
- Pyrometric cones and digital readouts confirming temperature
- Same glaze treatments
- Pieces were identical [or as close as possible], part of the same batch
I took photos of the cones and some of the bloated vs non-bloated pieces. Not sure if they would help, but can post. I also dropped IMCO an e-mail to see if anyone has had similar issues.
My main issue is that the glazes I have available mature a little better at ^6 than ^5, and if I can't nail this down then I may have to switch clay bodies.