I need some advice. Here's my problem. I fired to my kiln to cone 9. The witness cone seems to concur that cone 9 was reached without over firing.
Clay Body: Loafer's Glory and Phoenix.
Commercial Glaze: Mayco Stoneware glazes for cone 5/6 -- but is also indicated that it would be okay at 9/10.
Kiln: I'm using a Skutt Kiln with an electric kiln setter. I selected the Medium firing speed, with a 2 hour preheat, and a 5 minute soak. It took 13 hours to reach temperature.
I have an envirovent too and tested it pre-fire to make sure it was working.
I had some pieces with:
* Cinnabar Stoneware Glaze - perfect results (no blistering, smooth glossy finish, etc)
* Capri Blue and Green Tea stoneware glaze - pretty good with some minor blistering.
* Smoke Stoneware glaze - blistered like crazy! And came out a deep, deep blue.
From the research I've done online, I'm pretty positive the pieces are blisters and not pinholes, since they bubble-like and many have sharp edges. This is the first time I've used the Smoke glaze and in retrospect, should have probably fired it to cone 6 at least once before trying it at cone 9. Fire and learn.
I would like to refire the pieces that blistered to smooth out the glaze. I'm wondering if I should
* refire to cone 6 or to cone 9?
* adjust the speed?
* adjust the cool down?
* adjust the soak time?
I've found different advice online. Some articles suggested refiring for blistering was probably futile. Just wondering what you folks think.
Thanks a bunch for any advice and wisdom you care to share!