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greentypewriter

Under Fired Bisque

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I fired some greenware last night to cone 04 but the sensing rod wasn't properly set and it under-fired. Should i fire the bisque again or just glaze them and fire them at cone 05 as usual? They seem like they fired long enough to become sturdy and hold glaze. Thanks.

-Kelly

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do you worry about things a lot?  would you feel more comfortable knowing they reached bisque temperature?  is your electrical cost high?  is there a deadline involved?  can you risk failure on these particular pieces?

 

sturdy and hold glaze could be enough for some people, is it for you?

mregecko likes this

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In most cases a slight underfiring wouldn't be a problem, especially since 04 is a little on the high side for a bisque firing, but you say that the glaze firing is to 05 which is lower than the bisque so if the pot is supposed to be fired to maturity then it depends on the bisque to reach maturity instead of the glaze firing. In which case you do need to take it up to 04 before you glaze it. Now, if you made a mistake and meant that the glaze firing is to be to cone 5 (instead of cone 05) then there's no problem.

 

If you did mean cone 5 instead of cone 05 then there is probably no reason to waste the time and elect needed to go to 04. Unless there are inpurities in the clay that need to burn out 06, 010, or even 012 will probably be high enough. I bisque most clays to 012 because it's faster, cheaper and less wear on the kilns, but one clay I use has to go up to 05-04 to prevent bloating. Like everything else in pottery, don't depend on what you're told or what is written on the box--TEST.

 

Jim

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Welcome to the forum!

 

Sometimes in forums you have to read an answer a couple times to see if you are seeing things that are not there. I could be wrong, but I think the poster was just trying to judge how precise or loose you were. You don't know until you ask and it makes a difference in the advice you give. Some of us would re-fire and others would say it was close enough.

TypicalGirl likes this

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thanks chris, i think i was just pointing out to the questioner that just asking the question points you toward the answer that is comfortable for you.  the subsequent answers still do not say DO THIS, they still suggest rather than demand.  this is one of those areas that are decided by the person asking the question based on that person's feelings, nothing scientific or absolute.  feelings matter, i did not intend to insult someone.

TypicalGirl likes this

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Thanks everyone. Sorry, didn't mean to be so defensive right off the bat.

 

I'm using a Highwater red earthenware clay that i've used for years but

i wasn't sure if re-firing would be too much stress on the pieces.

I stupidly moved the kiln but didn't check the calibration on the sensing rod for

the cone before firing again. (lesson learned)

 

The pieces are for a project that's due this week so I didn't want ruin them

and also didn't want to give someone inferior work. But I've decided they fired

enough to just move forward. I'll just cross my fingers for this glaze firing tonight.

 

I've read through several other topics in the forum and there's lots of great info

here.

-kelly

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Hi Kelly. Welcome to the forum! Every one here really does try to help. Please realize that sometimes responses are made quickly and the written word sometimes gets misconstrued. There have certainly been times when I have read a response that I had to give pause to and re-read because I thought someone was being an ass.

 

To address your question, I don't think a slight under fire in the bisque will effect the outcome if the glaze fire is done properly. I bisque at 05 and 04 for a final fire at 5 or 6. I've mixed them up on occasion and never had a problem.

 

Cheers,

Pam

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