Clay Fatigue?

[MLW]

In a recent glaze firing at our community studio, something exploded and we wonder whether it might have been one or more of the bisqued "cookies" placed under a couple of pieces in case of possible glaze drips. These cookies have been used in multiple glaze firings - let's say perhaps 4 - 6, not sure. No thrown / glazed pieces blew up (as far as we know), though some were damaged, of course, from the bisque fragments embedded in them. Someone suggested clay fatigue as a possibility, saying that on occasion a ceramic baking dish used for some years can explode in the oven (and wouldn't THAT be a mess!).

 

Can anyone offer ideas about this? Thanks.

[minspargal]

I have used cookies a lot more than six times and never had any explode, I think Norm is right.

[Chris Campbell]

I fire unglazed pieces over and over again and all they do is crack, not explode. I agree ... Some piece was wet, perhaps from being freshly glazed then put directly into the kiln without time to dry?

Also of concern is this urban legend type tale of a casserole dish exploding from clay fatigue. It probably cracked because it was put into a hot oven directly from the fridge or freezer. I have never heard of a pottery piece exploding in a regular oven.

I have also heard third party tales around microwaves. Wet pieces taken from a dishwasher and put in a microwave can get hot enough to crack but do they explode?? These stories are always told as ... "A friend of mine heard ......"

[Marcia Selsor]

I have used my coils in many many firings and they don't blow up or crumble.

On the other hand, I have certain little bowls we use for sauces that heat up differently in the microwave. Ine glaze really retains the heat. All the sauce bowls are porcelain...no iron.

 

Marcia

[Chris Campbell]

I have had this happen too ... I thought it was the clay body but maybe the glaze can affect this too??

[Idaho Potter]

Norm,

 

Who are you and where have you been all my life?  Great, lucid, plain english explanations.  Thanks. 

 

Does this also apply to Corelle ware?  A friend refuses to use any handmade pottery or Corelle because she thinks they will blow up in the microwave and/or oven.  I've always told her it's produced by using much higher temps than she could ever achieve in her kitchen.  How wrong am I?

 

Shirley

[TJR]

Norm,

 

Who are you and where have you been all my life?  Great, lucid, plain english explanations.  Thanks. 

 

Does this also apply to Corelle ware?  A friend refuses to use any handmade pottery or Corelle because she thinks they will blow up in the microwave and/or oven.  I've always told her it's produced by using much higher temps than she could ever achieve in her kitchen.  How wrong am I?

 

Shirley

Shirley;

[i almost called you Lucy there.] I could be lucid, but I won't wear a tie.

Are we still on for dinner, or have I been replaced by some "Johny come-lately?"

TJR.

[Biglou13]

Not fatigue

 

I think it's PTSD, The clay is suffering from post traumatic stress disorder.

 

Or it's the clay version of spontaneous human combustion.

 

Did you make proper offerings to the kiln gods? Did you have appopriate kiln guardian in studio near kiln prior to firing?