Fail Number 2

Fail number 2, time to build different vessel with new clay. My kiln at cone 5 fires to cone 4 temp so logic says cone 6 should fire to cone 5 temp eh? Nope six on the dot. No worries though. I’ll make something even better 🙂

This clay, which I believe contains manganese, needs to not be over fired and needs a loooong bisque to burn off any gasses and other things that can cause bloating. Which I did. A 13 hour slow bisque to cone 05. But in the end it blistered anyways because of over firing.

Blisters

Celebrating Failure

Pretty much everything that could have gone wrong with this last firing has gone wrong.

Clay body cracks
Crazing
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Crazing reduces the strength of the vessel by up to 80% A short drop to the wooden floor split this right in half.
Blistering AND crazing
Blistering
Blistering
Pinholing AND Blistering
Pinholing like a CHAMP!
Even a bit of reduction in part of the kiln. Although I must say the reduction looks beautiful!

I’m picking up some dry materials to start testing my base glazes. At least I know that my chosen clay body tolerates overfiring very well.

I’m getting some witness cones (5, 6 and 7) to stack on each shelf and see what they do. I don’t understand whats happening yet. Olympic says that the kiln usually underfires if something is wrong rather than overfiring. The company that makes my clay body says that blistering happens from overfiring. The cones should tell the tale though. I need to get that straight before I drive myself crazier than usual.