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Under Fired Glaze


ronfire

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I messed up and thought the cones were done. Once I opened the kiln and saw the underfed glaze I went down further in the kiln to find the cones where not bent at all. Must have been blind or being things, was not even drinking. 

Should I reuse the cones and sitter bar to get the proper heat works or put in new bars and cones.

 

My guess is to reuse them but I thought I would check first.

 

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Nope! Put in new cones and start all over again. I must admit. I'm a bit confused as to why you would even open the kiln before your cone sitter would have tripped and shut the kiln off. Did you have a power outage during your firing? Color me confuzzled here! :blink:

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I thought all the cones where done so I shut the kiln off.

I have had a sitter stick and overfire so I use both cones and sitter. This was also a first time I fired a glaze in this kiln so I am still fine tuning the sitter.

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Never reuse heated cones- unless they are just taken up to oven temps.It's asking for errors

I now would really set the cones up better so you can view the cones if you thought they where all down.Get the right glass for viewing and read up on this as its been posted about ALOT here.Viewing cones is like throwing pots it takes practice.

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I usually have no problems seeing the cones as I have an element behind them to see them clearly. For some reason I must have looked in and thought all the cones where down. I must have looked at a different element section and missed the cones. Well learned to look closer.

This was a first glaze fire with a smaller kiln and thought it fired fairly fast. 

Did a refire yesterday and am waiting for it to cool.   

What I did find out is the top section fires almost 2 cones cooler than the mid and bottom. Managed to turn down the centre and lower section to allow the top to heat up more. 

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Refired pots are tight (clay is already fired) so you need to heat them slower going up and longer cooling times. Every time they are fired they get a tad weaker. 3 times is one to many in my studio-I will only retire once and the larger the form (like a plate is loaded in the bottom of kiln) so heating happens slowly. Deciding on what can be retired is also a factor as refiring does not work well with some issues and forms. (usually about 50% success rate)

I have learned that tossing the pots often is better use of kiln space.Plates/platters/large bowls/pie plates are one of those forms that often do not refire well .

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