compression problems using 2 different inside/outside glazes ?

[sandi]

using 2 diff. commercial glazes for inside and outsides of bowls / mugs etc - losing MANY with dunting !  These glazes are supposed to be compatible. Sometimes dunt occurs 2 weeks later after leaving the kiln. Advise ?  thx

[yappystudent]

I've been wondering about this too, I like to 'double dip' vessels sometimes two different colors and I've noticed one side will compress much thinner than the other. So far I haven't lost anything probably due to using mostly groggy clays, but it looks a little odd up close. Didn't know there was a name for it. 

[Min]

Have you tested the glazes using just one on both the inside and the outside of the pots? The glazes might be compatible with each other but not with your claybody. If the glaze(s) are low expansion and your clay isn't that could be the reason for your dunting. I would take some of the survivors and put them in the coldest part of your freezer overnight, in the morning put them in the sink and pour rapidly boiling water into the frozen pots. I think there is a good chance you will see more dunt. How did you find out that the two glazes are compatible?

[MartinB]

What Min said, try glazing with only one glaze on both the inside and out, it might be that the glaze is not that compatible with your body.

It could also be that you have different amounts of glaze on the inside vs the outside depending on which you dipped first. The body absorbs some water with the first one, then the second application doesn't draw as much water so you end up with a thinner coating. You could make sure the body is completely dry after the first dip, or give the second dip more time to build up a thicker coating. Depends on the thickness of your body, what temp you bisqued at etc Its a process of elimination.

Good luck!

Edit: Do you have a link to the glazes? Am curious about them being compatible...