Dave Finkelnburg on wed 27 feb 02
My initial reaction to Ron Mitton's question,
> If a firing has to be aborted midway =
>> to acquired temperature, on restarting would fresh/new cone packs be =
>> required??
was the same as Paul Lewing's, put new cones in. Then I wondered, if the
firing is interrupted, wouldn't the cones in the kiln have "recorded," so to
speak, the heatwork done to that point, and actually give a BETTER
indication of when the firing is complete than new cones would?
I have never tried this, I am just wondering.
Dave Finkelnburg
Ron Roy on wed 27 feb 02
Depends what temp you stopped at - if below 800C nothing much will have
happened melt wise.
I'm thinking out loud - sometimes not the safest thing to do - but I would
say use the same cones - yes I am sure (oh oh) - the cones have already
kept pace with the ware no matter - so both have the same amount of heat
work - if you put new ones in - the ware has already had some heat work so
I would say you would end up with slightly over fired work - if you
aborted near the end it might be more than slightly overfired.
RR
>Hi All,
> Could Clayarters advise. If a firing has to be aborted midway
>to acquired temperature, on restarting would fresh/new cone packs be
>required??
>
>
>Regards,
>
>RON MITTON
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Gavin Stairs on wed 27 feb 02
Hi Paul,
I'm glad you answered this question, because in my mind it's not about
saving the price of a cone, but which is the correct way: which would give
a truer indication of the maturity of the load. It would seem to me that
the correct way would be to reuse the cones, as they have had the same heat
work as the rest of the load, and would therefore come to maturity at the
same time as the load, even after stopping and starting.
That would be true if all the assumptions about cones were true, which of
course they are not. First difference: cones are fired not just to
maturity, but well over maturity to the slumping/bloating stage. So the
two heat work ramps of the work and the cones are not exactly similar in
any case. We might expect the cones to begin their changes rather sooner
than the work. So, refiring would perhaps give the cones more heat work
than the rest of the load. This effect would be less for vitreous ware
than for open ware, and might be reversed for glazes, which go ever farther
than cones past a clay-type maturity point. Second difference is that the
cones are not the same recipe or type of material as the bodies and
glazes. They are made from a slurry or powder intended to reproduce
fusibility characteristics, and not to be plastic, etc., etc. So they have
different materials, and are formed differently.
So, to me the answer is not as obvious as the Orton man indicated. I would
reason that if the firing were a bisque, I'd use a new cone pack, but if it
were a glaze firing, I'd leave the old one in. Maybe place a new pack in
there as well. With the old pack, a bisque load might lag behind the
cones, so to be sure I reached bisque maturity, I'd want the new cone pack
in. But a glaze load might be ahead of the cones, so I wouldn't want to
make a bad situation even worse by firing with the new cone pack.
Of course, if the firing stopped well before the onset of irreversible
changes, say before 400 or 500 C, it wouldn't make much difference in any
case. Probably wouldn't matter much until 900 or 1000 C or above.
Does anyone have any experimental evidence on this?
Gavin
At 03:02 PM 27/02/2002 -0800, Paul Lewing wrote:
>on 2/27/02 12:21 PM, jean mitton at mittyj@IAFRICA.COM wrote:
>
> > If a firing has to be aborted midway =
> > to acquired temperature, on restarting would fresh/new cone packs be =
> > required??
>
>Hi, Ron. A couple of years ago when NCECA was in Columbus, I asked that
>very question to the folks at Orton. They said, "We've never tested that,
>but why in God's name would anyone reuse a cone? They're incredibly cheap.
>Why would you risk a whole load for the price of a cone?"
>Incidentally, I have refired guard cones from firings that had to be shut
>off early, and noticed no difference from the fresh guard cone. But I've
>always put a fresh cone in the sitter.
>Paul Lewing, Seattle
jean mitton on wed 27 feb 02
Hi All,
Could Clayarters advise. If a firing has to be aborted midway =
to acquired temperature, on restarting would fresh/new cone packs be =
required??
Regards,
=20
RON MITTON
Paul Lewing on wed 27 feb 02
on 2/27/02 12:21 PM, jean mitton at mittyj@IAFRICA.COM wrote:
> If a firing has to be aborted midway =
> to acquired temperature, on restarting would fresh/new cone packs be =
> required??
Hi, Ron. A couple of years ago when NCECA was in Columbus, I asked that
very question to the folks at Orton. They said, "We've never tested that,
but why in God's name would anyone reuse a cone? They're incredibly cheap.
Why would you risk a whole load for the price of a cone?"
Incidentally, I have refired guard cones from firings that had to be shut
off early, and noticed no difference from the fresh guard cone. But I've
always put a fresh cone in the sitter.
Paul Lewing, Seattle
Craig Edwards on wed 27 feb 02
Hi Ron; If none of the cones have started to go down yet, I would go with
them. They have seen the same duty as the pottery.
Craig Edwards
new London MN
>Hi All,
> Could Clayarters advise. If a firing has to be aborted midway
>to acquired temperature, on restarting would fresh/new cone packs be
>required??
>
>
>Regards,
>
>RON MITTON
>
>______________________________________________________________________________
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KLeSueur@AOL.COM on wed 27 feb 02
I don't know if new cones are required. But if a bisque is interrupted at the wrong time you'll probably have lots of fine cracks in the ware that won't be noticable until after the glaze firing.
Kathi LeSueur
Cindi Anderson on wed 27 feb 02
If you really have only fired to half temperature, the cones haven't
absorbed much energy yet relative to the whole, so it probably wouldn't
matter. But even if you were closer to the final temperature, I would say
keep the same cones, because they are going to be an accurate reflection of
what your ware has seen.
Cindi
----- Original Message -----
From: "jean mitton"
To:
Sent: Wednesday, February 27, 2002 12:21 PM
Subject: Interupted Firing "Cones"
Hi All,
Could Clayarters advise. If a firing has to be aborted midway to
acquired temperature, on restarting would fresh/new cone packs be required??
Regards,
RON MITTON
Anne Wellings on thu 28 feb 02
On Wed, 27 Feb 2002 19:29:12 EST, KLeSueur@AOL.COM wrote:
>I don't know if new cones are required. But if a bisque is interrupted at
the wrong time you'll probably have lots of fine cracks in the ware that
won't be noticable until after the glaze firing.
>
>Kathi LeSueur
I didn't know this and I'm sure I've refired aborted bisques or seen others
do it. Is there a specific "wrong time" at which you would have to worry
about this if, say, the electricity went out?
I have never re-used cones from aborted firings because of the heatwork
that has already happened on the old cone. But then, as others have pointed
out, the heatwork has happened on the pots, too, which gives me something
to think about.
Anne
KLeSueur@AOL.COM on thu 28 feb 02
In a message dated Thu, 28 Feb 2002 3:05:57 AM Eastern Standard Time, Anne Wellings writes:
> On Wed, 27 Feb 2002 19:29:12 EST, KLeSueur@AOL.COM wrote:
>
> >I don't know if new cones are required. But if a bisque is interrupted at
> the wrong time you'll probably have lots of fine cracks in the ware that
> won't be noticable until after the glaze firing.
> >
> >Kathi LeSueur
>
> I didn't know this and I'm sure I've refired aborted bisques or seen others
> do it. Is there a specific "wrong time" at which you would have to worry
> about this if, say, the electricity went out?
I would guess that around quartz inversion is the critical point. But others with better technical knowledge could give a more accurate answer.
I had a problem years ago with an inadequate electric source to a kiln. The breaker would keep tripping. I had to have the line upgraded. But all of the pots bisque fired during that period had those fine cracks. years later we had a power failure here during a bisque. It must have been at a critical point because once again those fine cracks appeared.
Kathi
Earl Brunner on thu 28 feb 02
A way to find out. Put the used cones next to a new set of cones and compare after
the second firing.
Dave Finkelnburg wrote:
> My initial reaction to Ron Mitton's question,
> > If a firing has to be aborted midway =
> >> to acquired temperature, on restarting would fresh/new cone packs be =
> >> required??
> was the same as Paul Lewing's, put new cones in. Then I wondered, if the
> firing is interrupted, wouldn't the cones in the kiln have "recorded," so to
> speak, the heatwork done to that point, and actually give a BETTER
> indication of when the firing is complete than new cones would?
> I have never tried this, I am just wondering.
> Dave Finkelnburg
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Gail Dapogny on thu 28 feb 02
The motor that mixes the gas and air on our potters' guild 70 cub ft gas
kiln once gave out, and I'm thinking that it was probably between 1500-1700
F -- possibly slightly higher. It was then off for a good 6 hours while JT
(Abernathy) found a new used motor and replaced the old one. Then was
restarted and fired to the end. Everything came out healthy and looking
the way it normally does. Same cones.
That's of course a reply based only on a single experience. Ron Roy's
educated and thought out response makes the real sense.
----Gail
>Depends what temp you stopped at - if below 800C nothing much will have
>happened melt wise.
>
>I'm thinking out loud - sometimes not the safest thing to do - but I would
>say use the same cones - yes I am sure (oh oh) - the cones have already
>kept pace with the ware no matter - so both have the same amount of heat
>work -
>RR
>>Hi All,
Could Clayarters advise. If a firing has to be aborted midway to
acquired temperature, on restarting would fresh/new cone packs be required??
>>
>>Regards,
>>RON MITTON
Gail Dapogny
1154 Olden Road
Ann Arbor, MI 48103-3005
(734) 665-9816
gdapogny@umich.edu
marikocruse on thu 28 feb 02
Hi Clayarters,
I am so glad to read this "Interupted Firing Cones". In Florida where I
live, the blackout, especially in summer time, is so often that I am always
scared to start firing. Would it be worthwhile to invest in a some kind of
backup power source? Or, would it be cheaper to remake the pots? Any
comment? Mariko
----- Original Message -----
From: "Dave Finkelnburg"
To:
Sent: Wednesday, February 27, 2002 9:41 PM
Subject: Re: Interupted Firing "Cones"
> My initial reaction to Ron Mitton's question,
> > If a firing has to be aborted midway =
> >> to acquired temperature, on restarting would fresh/new cone packs be =
> >> required??
> was the same as Paul Lewing's, put new cones in. Then I wondered, if the
> firing is interrupted, wouldn't the cones in the kiln have "recorded," so
to
> speak, the heatwork done to that point, and actually give a BETTER
> indication of when the firing is complete than new cones would?
> I have never tried this, I am just wondering.
> Dave Finkelnburg
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
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