[randyfristoe]

Hey all,

So I am experiencing with more regularity that the feet of my bowls and mugs are sticking to the shelves. Sometimes chipping off when I remove them.
every pot that i fire leaves a distinct brown ring on the shelves after they have been fired. and in time those collective rings cause the shelves to brown and even get a polish on them.

I fire cone 10+(11/12) in a gas kiln and use a stoneware body with just a hint of red clay cut into it for color and earthy speckling.

is this brown ring being caused by the iron in the clay or what other process is going on to cause my (unglazed) feet to stick to my shelves?

Can anyone shed any light on what is going on and offer a solution. I'm not opposed to kiln wash but would rather not have to.

thanks,
Randy

[OffCenter]

Your pots are being "welded" to the shelves. You may be firing a bit on the high side for that clay. Probably the easiest solution is to stir some alumina hydrate into the wax that you use or just sprinkle a little under each foot then put your shoes back on. Even though that should stop the welding, you still need to do tests to see if you're over firing your pots. Throw small cylinders and leave unglazed. Fire one cone lower. Fill cylinder with water. Leave on sheet of paper over night. If absolutely no leaking then your clay is mature at that cone and you have been over firing which actually makes the pot a little weaker.

Jim

[koreyej]

Yep, what offcenter said. Your clay is maturing at a lower temperature and is actually starting to melt. Try doing what she suggested and see if firing at a lower cone will give you vitrification. If so, then just fire a little lower.

Years ago, I joined in on a woodfire where the stokers got a little carried away and the work was overfired. We had similar results. Good luck!

[OffCenter]

koreyej, on 13 November 2012 - 01:09 AM, said:

Yep, what offcenter said. Your clay is maturing at a lower temperature and is actually starting to melt. Try doing what she suggested and see if firing at a lower cone will give you vitrification. If so, then just fire a little lower.

Years ago, I joined in on a woodfire where the stokers got a little carried away and the work was overfired. We had similar results. Good luck!

"she"!!!!!!!!!!!!!!!!!!!!!!!!!!!!