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Cautionary Tale


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It is easy to procrastinate, for me anyway. About six months ago, a small glob of crystalline glaze missed the catcher and landed on the kiln floor. I always fire cone six, so it never became a problem. A week ago I decided to test a cone 11 porcelain body and fired up to 2345F. That little 1/2" glob melted through the bottom of the kiln, creating an exhaust port for 2345F heat to come out. (Think rocket booster at NASA.)

So here is the photographic evidence and a cautionary tale about kiln safety and upkeep.

 

Nerd

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Peek-a-boo, I see youuuu... Yup, we had a glaze disaster on the bottom shelf in one of the school kilns, where the lava flow went down between the half shelves and dripped onto the soft brick. It didn't eat a hole all the way through like yours, but a substantial melt hole. We brought the base of the kiln up into the studio and repaired it during class time as an object lesson to the students about why we are so picky about cone numbers (the zero is meaningful, really, trust me, 06 is not 6...), clay bodies, and glaze application.

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Guest JBaymore

Now you can add a gas burner under there and do reduction crystalline glazes.  ;)

 

Glad nothing caught on fire outside the kiln.

 

best,

 

.................john

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Bummer, dude. With most glazes that won't happen to that degree, because they don't flow like crystalline glazes. A typical cone 6 glaze fired up to cone 10 probably won't flow more than a crystalline fired to the correct temperature.

 

One problem I have seen is in studios (schools mostly) that do both low fire and cone 6. If they blow up a low fire pot and the shards get on the elements, and they don't vacuum it out well, those shards will melt in the next cone 6 firing and make a mess on the elements.

 

I had one customer that kept blowing up low fire work and never vacuumed out the bottom element. All those shards caused hot spots that eventually melted the shards, even though he never fired above low fire temps. Eventually the bottom element was just a big tube of glass fused into the bricks.

 

Patch up that hole and fire on!

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Spectacular.

I have a gob on my kiln floor which I haven't excavated.....dropped from above missing walls and elements.

Should I shouldn't I?

Marcia what are you calling castable just in case.

Neil I'm believing your advice from months ago and so far everything fine. I will never, what's that word?, fire higher than c 6

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Spectacular.

I have a gob on my kiln floor which I haven't excavated.....dropped from above missing walls and elements.

Should I shouldn't I?

Marcia what are you calling castable just in case.

Neil I'm believing your advice from months ago and so far everything fine. I will never, what's that word?, fire higher than c 6

That was in 1973 . Maybe is was Mizoram. Can't really remember. Could have been Sairset.Marcia

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the last picture should be first.

 

just had a disastrous firing for the first time in many years.  knew better, the bottom of the pot that blew was too thick.  the pot was there to see if i could successfully add a slab to a thrown bottom.  that worked but the whole thing blew up and affected 17 pots all over the kiln.

 

 added to that, i had just sprayed the glaze and it was probably a little wet.  cannot explain the pink one but it is better to have 2 go bad in the same firing than have two bad firings.

 

after vacuuming the kiln, i have set up a new glaze firing today.  hope it works better than this one did.  

 

edit to add, the small square was my nerd clay slab piece.  sorry tom.

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Oldlady:

 

Apparently this is the month for kiln "episodes." Got all the repairs done on The Delta Rocket (my kiln nickname now) and now the controller shot craps..alas. Decided to hold off all firings until September, perhaps then something will not melt or explode. Sorry for your loss, not a good month so far.

*** have two molybdenum glazes sitting in there waiting to be fired to 2345F.

 

Tom

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Well my new controller arrives today. I was thinking if I drilled out the 1/2" hole the glaze made in the bottom of the kiln; then strapped a couple of 100lb propane tanks to the side: I might be able to land it on the moon. "The Glaze Orbiter", I like it!!!!!

 

Nerd

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