Post #587149 by Babalu on Fri, Apr 29, 2011 4:27 PM

The muggies are looking great kiddo!!

On 2011-04-29 14:49, danlovestikis wrote:
MDM, nope never burnished any of them. I think it has to do with the clay shrinking more than the glaze. Well we just have to keep trying to follow all the rules and hope for the best.

VERY GOOD - A+ :up: :)

It's called Shivering...
Shivering happens when a glaze doesn't shrink as much as the clay body.
When this happens parts of the glaze crack and move against each other lifting off from the clay surface.

Suggested Remedies:

Reduce silica in the clay body
Reduce silica in the glaze
Reduce alumina in the glaze

If you like those particular store brought glazes you are using, ask your clay supplier for a low fire clay with a little less silica in it. That should solve the problem. You can also try holding the final temp on your bisque firing for 5 to 10 mins...just to make sure that the clay matures completely. Kilns do tend to fire at uneven temps...a short hold at the end of the firing will help catch those cooler spots in the kiln.

YAY!