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#1 Rebekah Krieger

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Posted 14 January 2013 - 09:03 AM

How long do you allow your items to dry before they go into the kiln for the bisque fire? The reason I ask is when I see workshops advertise that a bisque firing is included a day or two after they are made. I was under the impression that they needed to be much much drier. I let my items dry for a minimum of a week before they get fired. They seem to me unoficially "bone dry" (not the technical term). Do people bisque fire leather hard items? (leather hard is what I think of as "trim time" but I might be wrong on the definition)
Learning On my Kick wheel with my vintage Paragon (from the late 1960's)

#2 TJR

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Posted 14 January 2013 - 10:38 AM

Rebby;
Once again you have the great question. Please DO NOT FIRE leatherhard pots! You will blow them all up. If you are not sure your pots are dry, hold them up to your cheek. If they are cool on your skin, they are still moist.
If you have moisture in your pots, and you apply heat, as in placing them in a kiln, the moisture turns to steam, and KABOOM! More of a dull whoomph.
I don't know how you could bisque in two days. A week sounds good.
TJR.

#3 Rebekah Krieger

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Posted 14 January 2013 - 10:52 AM

Rebby;
Once again you have the great question. Please DO NOT FIRE leatherhard pots! You will blow them all up. If you are not sure your pots are dry, hold them up to your cheek. If they are cool on your skin, they are still moist.
If you have moisture in your pots, and you apply heat, as in placing them in a kiln, the moisture turns to steam, and KABOOM! More of a dull whoomph.
I don't know how you could bisque in two days. A week sounds good.
TJR.


that's what I thought too! But when I read descriptions of some pottery events some of them say that pieces made will be bisque fired... but the events are only 3 days long. sounds impossible to me, i was wondering if there was a secret I needed to know about lol.
Learning On my Kick wheel with my vintage Paragon (from the late 1960's)

#4 Chris Campbell

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Posted 14 January 2013 - 11:33 AM

I think every teacher hopes for a Workshop week of sunshine and dry weather.

I do fire during a weekend workshop and several times during a week long one ... my students are usually making small test items and thin color samples so it is very easy to fire those from an almost wet stage ... one thickness, small size, no pressure or stress points. I fire some of my larger test pieces for them to see, but once again ... very simple, one thickness, no stress anywhere ... and a VERY forgiving clay body.

The time constraints of workshops usually demand firing before work is ideally bone dry ... instructors try very hard to get the work dry by using hot boxes or fans or whatever is around because students want to carry work home and that means at least one bisque firing. If things are still too damp then I'll stay up late and candle the load until I can start the bisque rolling.

But Murphy's Law takes over most of the time ... everything you don't care about comes out perfect and every crucial piece explodes.

Workshops should be places where you come to learn ... not where you are making anything special. I'm not saying you can't ... but I've seen students put so much pressure on themselves to make something crucial, when they could be enjoying the experience of learning without pressure and negative consequences.

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#5 TJR

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Posted 14 January 2013 - 02:13 PM


Rebby;
Once again you have the great question. Please DO NOT FIRE leatherhard pots! You will blow them all up. If you are not sure your pots are dry, hold them up to your cheek. If they are cool on your skin, they are still moist.
If you have moisture in your pots, and you apply heat, as in placing them in a kiln, the moisture turns to steam, and KABOOM! More of a dull whoomph.
I don't know how you could bisque in two days. A week sounds good.
TJR.


that's what I thought too! But when I read descriptions of some pottery events some of them say that pieces made will be bisque fired... but the events are only 3 days long. sounds impossible to me, i was wondering if there was a secret I needed to know about lol.


Don't they mean bring bisqued pots to the event, as in loading a wood fire, and everything loaded must have been bisqued previously?
TJR.

#6 Rebekah Krieger

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Posted 14 January 2013 - 03:01 PM



Rebby;
Once again you have the great question. Please DO NOT FIRE leatherhard pots! You will blow them all up. If you are not sure your pots are dry, hold them up to your cheek. If they are cool on your skin, they are still moist.
If you have moisture in your pots, and you apply heat, as in placing them in a kiln, the moisture turns to steam, and KABOOM! More of a dull whoomph.
I don't know how you could bisque in two days. A week sounds good.
TJR.


that's what I thought too! But when I read descriptions of some pottery events some of them say that pieces made will be bisque fired... but the events are only 3 days long. sounds impossible to me, i was wondering if there was a secret I needed to know about lol.


Don't they mean bring bisqued pots to the event, as in loading a wood fire, and everything loaded must have been bisqued previously?
TJR.


no- they were working with clay and bisque firing their work. I just found it odd...
Learning On my Kick wheel with my vintage Paragon (from the late 1960's)

#7 JLowes

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Posted 14 January 2013 - 04:28 PM

At a Steven Hill workshop I attended, he threw a couple of pots on the first day, saying they would be force dried to show his spraying techniques the next day. I assumed they would candle them overnight, but no, they were dried out the morning of the spray day while he went over his glaze theory, no more than three hours if that. Electric kiln, 180-200 degrees F for a few hours will dry out pots so they can be bisque fired (or spray glazed.) I would think the main issue could be space using this method.

As Chris mentioned, warm sunny days can do the same. I have dried out pots from thrown to ready for bisque firing same day when the sun and wind and humidity all cooperate.

John

#8 bciskepottery

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Posted 14 January 2013 - 07:51 PM

Some potters use a drying tent -- plastic over shelves, with small (computer-size) fan circulating air to dry things out. I've also seen studios that use heat lamps to speed dry -- think lamps used to keep the fries hot. Best solution is to let them dry on their own time table.

#9 yedrow

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Posted 14 January 2013 - 09:54 PM

It depends on how thick the piece is and how humid the atmosphere is. I've heard that altitude can also effect drying time too. When it comes to thickness, watch out for knobs and handles. A piece that is 1/8th in thick on the walls and bottom can easily be 1/2 in. thick where a handle or knob attaches. Always allow for longer drying times in such cases. You can put the back of your hand to a pot bottom and get a good idea. On an unattached cylinder the bottom will generally be the last part to dry.

That being said, I make it a rule to let all thick objects dry longer. And, in the case of knobbed or handled objects, I always soak the kiln under 200˚ for two to four hours before ramping up.

Joel.

#10 Diane Puckett

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Posted 14 January 2013 - 10:41 PM

There are folks who fire wet pots. I recently read about this, though I cannot remember where I read it. Apparently the humidity level in the kiln is high enough that pots do not explode as you would expect. If my old brain remembers the source of this information, I will post it.

In the meantime, I found this via Google Wet Firing
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#11 Lucille Oka

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Posted 14 January 2013 - 11:57 PM

Rebby, as a rule most potter's know that firing leather hard clay has potential disaster written all over it. But then some 'smarty pants' will come along try it and nothing adverse happens. It ruins what we know and believe to be a mistake. Once an instructor went so far as to put a freshly thrown vessel in the kiln to prove the point that ware must be bone dry before being placed in the kiln. As the class stood around waiting to see the disaster the kiln was opened and there was nothing wrong.
Now fate is fickle this we know, but what do you tell folks after that.
We know that as a rule firing damp ware isn't the best idea and when someone asks about it we will most likely say 'don't do it'. But if you want to try and be a 'smarty pants'......


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#12 Chris Campbell

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Posted 15 January 2013 - 03:09 PM

It also depends on your clay body ... Some are very forgiving and you can do just about anything to them and it works out fine and others will not tolerate anything much. I had a clay in Seattle that you could probably fire right off the wheel and it would be great ... so we put a lot of very wet work into the bisque firings with no problems. If you live in damp, rainy Seattle that is definitely a big plus.

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#13 DAY

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Posted 15 January 2013 - 04:17 PM

If you are unsure if your pots are dry enough, keep the kiln on low and hold a mirror over the spy hole. If it fogs, there is still water inside.

#14 Diana Ferreira

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Posted 15 January 2013 - 05:43 PM

I have fired stuff casted on the same day. But I work thin, my clay allows it, etc. I am NOT a smarty pants. I try and figure things out, question, try again, sleep over questions, ask peers and try again. Just because a rule has been laid down, does not mean that it is carved in stone. Having the attitude that everything that is not according to the holy grail of ceramics will fail or is wrong; is like living in the dark ages, refusing to accept that life is easier with what we know now, vs candles and buckets of water and a pit toilet.

But what I do do is to take care of my elements. I always close my bungs with a bisque kiln at 600C. And if the work is really wet, I will add an extra ramp to my firing schedule with the first one very slowly. I might even hold it at 90C for an hour ...
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