jonathan byler on fri 4 apr 08
I am having trouble getting our gas kiln to fire evenly early in the
firing. by the end, everything usually works out o.k., depending on
how it is stacked, and where the bagwall sits, it can get to less
than a half cone difference top to bottom. The evenness early in the
firing is an issue because the top goes through body reduction,
(start about ^012 - end about ^08) the bottom is just getting up to
^012, sometimes a little hotter. is there some secret to getting the
top and bottom to temp at about the same time early on? Do I need to
stagger the shelves more front to back? I usually try to get a layer
or two of taller pots towards the bottom to allow more flow through
that part of the kiln, which definitely seems to help the overall
evenness of the temp reached (^10).
I am trying to follow the firing schedule laid out in cushing's
handbook to some extent, but he raises the temp overnight to about
1652F (^010) and then does body reduction. our kiln has forced air
burners which don't really work so well at low settings, and I don't
like to start the firing other than using the pilots to dry
everything out well - about 191F when I get in in the morning, on the
off-chance that I won't make it in to work, and will get the kiln too
hot for the initial reduction, or some other mishap) It seems that
the length of his firing schedule is what permits the kiln to
presumably be more even in temperature top to bottom when he starts
reduction. I have noted that slowing the kiln in general seems to
promote more even heating within it, which makes me also wonder how
those of you who fire fast (say 4-6 hours) manage to get even
heating. I am all for speeding things up, as it means that I can go
home earlier on fridays when I usually fire the kiln, but not at the
expense of having unpredictable or undesirable results from such a
fast firing.
Any input much appreciated. thanks,
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
Michael Wendt on sat 5 apr 08
Jon,
Get a dual probe pyrometer if you don't have one.
Also...
It might do to look into very small forced air
burners to add to the larger ones for overnight
warm-ups. By morning you would be above
1625 F with the correct heat input so kicking
in the big burners would be a breeze.
I have been toying with this idea for some
time but can't use it on my updraft.
As to how we get even firings on our
updraft Olympic style kiln:
I have a Cole-Parmer dual probe pyrometer
which allows reading from both the top and
the bottom of the kiln. Adjustments as little
as 1/8" in the damper can cause either the top
to lag or catch up. Near the end of the firing,
I open the damper a little at a time until the
bottom heating slows. The passing incoming
cool air heats as it rises and carries the heat
up to the top where it is needed.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
Jon wrote:
I am having trouble getting our gas kiln to fire evenly
early in the
firing. by the end, everything usually works out o.k.,
depending on
how it is stacked, and where the bagwall sits, it can
get to less
than a half cone difference top to bottom. The
evenness early in the
firing is an issue because the top goes through body
reduction,
(start about ^012 - end about ^08) the bottom is just
getting up to
^012, sometimes a little hotter. is there some secret
to getting the
top and bottom to temp at about the same time early on?
Do I need to
stagger the shelves more front to back? I usually try
to get a layer
or two of taller pots towards the bottom to allow more
flow through
that part of the kiln, which definitely seems to help
the overall
evenness of the temp reached (^10).
I am trying to follow the firing schedule laid out in
cushing's
handbook to some extent, but he raises the temp
overnight to about
1652F (^010) and then does body reduction. our kiln
has forced air
burners which don't really work so well at low
settings, and I don't
like to start the firing other than using the pilots to
dry
everything out well - about 191F when I get in in the
morning, on the
off-chance that I won't make it in to work, and will
get the kiln too
hot for the initial reduction, or some other mishap)
It seems that
the length of his firing schedule is what permits the
kiln to
presumably be more even in temperature top to bottom
when he starts
reduction. I have noted that slowing the kiln in
general seems to
promote more even heating within it, which makes me
also wonder how
those of you who fire fast (say 4-6 hours) manage to
get even
heating. I am all for speeding things up, as it means
that I can go
home earlier on fridays when I usually fire the kiln,
but not at the
expense of having unpredictable or undesirable results
from such a
fast firing.
Any input much appreciated. thanks,
jon
jonathan byler on sun 6 apr 08
The kiln in question is a bailey shuttle pro32, sprung arch, down
draft, forced air (power burner), natural gas. I added an extra
brick to lengthen the bag wall this past firing, and I will try
spacing them apart a little in the next. There is a problem with the
bottom in the back initially getting too hot, which means that those
extreme back edge areas go through body reduction temperatures
earlier than the rest of the kiln, which keeps them from getting that
lovely warm color that the other pots get. So I will try to space a
little farther apart towards the front of the kiln. The bagwall, by
the way, extends about 6 bricks from the burner port and has a target
brick directly at the end. I put some cones down in the bottom at
the center-back area, and they only came down to a softish cone 9
with the ten cone at 2-3 o'clock, whereas the top front had the ten
touching, and the eleven about 2 o'clock, and the bottom front the
ten was just barely touching. I think If I move the bagwall too far
forward, that the bottom back will suffer yet more in terms of under
firing. By the way, we did fire a small kiln god with this load of
pots in order to ward of the bad spirits. Although I am loathe to
believe in such things, don't tell that to the kiln god!
I am going to try the slow heat overnight thing, but I hope that does
not become a regular affair. The pilots on this kiln put out a much
smaller flame at maximum power than the ones on the larger kiln,
despite being the same design. I need to compare orifices and
determine why this is, as we could get a much better start if the
pilots could pull their own weight. I have also thought about
setting up the controller on that kiln to do a hold/soak program, the
same as our other, larger, bailey gas kiln can do. It should just be
a matter of a few switches and relays, but I may have to change how
the pilots get their gas supply too.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 6, 2008, at 4:06 PM, John Fulwood wrote:
> Jon,
>
> I do not know how much this will help but, here goes. First, what
> kind of kiln are you firing? sprung arch, flat top, updraft,
> downdraft, commercial or site built. The ideal shape is a square.
> If it is rectangular....taller than wide, you are going to have a
> hard time getting things to even out early on. My kiln is rect. I
> will not build a kiln I cannot stand up in so I deal with a little
> unevenness. The beauty of a reduction kiln is that it has it's own
> personality. If it is well built, you will have many firings to get
> to know it well. Heat rises and sometimes you just have to accept
> what you get and enjoy the ride. The fun part is that just when you
> think you have it figured out, the kiln gods will put you in your
> place and you get to start again. I love my job. I am loading my
> kiln now and I hope I remember the secrets. I guess I will find out
> on Tuesday when I unload.
>
> If you lower your bag wall, you will get more heat in the bottom
> early on. You should also have some openings in the bag wall to
> allow some flame to be pulled into the bottom of the chamber. Maybe
> a target brick in the firebox to help break up the flame.
>
>
> good luck,
>
> John
>
>
>
> al Message-----
>> From: Loren JOnes
>> Sent: Apr 6, 2008 12:07 PM
>> To: CLAYART@LSV.CERAMICS.ORG
>> Subject: Re: firing the gas kiln evenly.
>>
>> I had great success using Vals schedule and forced air burners.
>> The slow over night firing did allow the temp to be more even. A
>> few times when things went wrong and the kiln shut off during the
>> night I would try to restart in the morning and the firings never
>> worked as well. My kilns were 36 cubic feet. One was a flat top
>> and the other was an arch. Both had identical burner systems. Over
>> night I had the damper at about
>> 2 1/2 inches Gas at 1.8" on the flat top and .8 on the arch. I
>> would adjust the air to achieve a fluttering blue flame. I did
>> this weekly for 13 years and had great results! You will need to
>> experiment with your kiln as to how much gas to use. Maybe start
>> it at 10pm and go in at 4:30am and see how hot it got. Than adjust
>> accordingly. I had a few times when it got hotter than I wanted
>> but not often. Keep in mind I was firing student work and not work
>> I was going to sell. Good Luck, Loren Jones
>> ----- Original Message ----
>> From: jonathan byler
>> To: CLAYART@LSV.CERAMICS.ORG
>> Sent: Friday, April 4, 2008 5:26:39 PM
>> Subject: firing the gas kiln evenly.
>>
>> I am having trouble getting our gas kiln to fire evenly early in the
>> firing. by the end, everything usually works out o.k., depending on
>> how it is stacked, and where the bagwall sits, it can get to less
>> than a half cone difference top to bottom. The evenness early in the
>> firing is an issue because the top goes through body reduction,
>> (start about ^012 - end about ^08) the bottom is just getting up to
>> ^012, sometimes a little hotter. is there some secret to getting the
>> top and bottom to temp at about the same time early on? Do I need to
>> stagger the shelves more front to back? I usually try to get a layer
>> or two of taller pots towards the bottom to allow more flow through
>> that part of the kiln, which definitely seems to help the overall
>> evenness of the temp reached (^10).
>>
>> I am trying to follow the firing schedule laid out in cushing's
>> handbook to some extent, but he raises the temp overnight to about
>> 1652F (^010) and then does body reduction. our kiln has forced air
>> burners which don't really work so well at low settings, and I don't
>> like to start the firing other than using the pilots to dry
>> everything out well - about 191F when I get in in the morning, on the
>> off-chance that I won't make it in to work, and will get the kiln too
>> hot for the initial reduction, or some other mishap) It seems that
>> the length of his firing schedule is what permits the kiln to
>> presumably be more even in temperature top to bottom when he starts
>> reduction. I have noted that slowing the kiln in general seems to
>> promote more even heating within it, which makes me also wonder how
>> those of you who fire fast (say 4-6 hours) manage to get even
>> heating. I am all for speeding things up, as it means that I can go
>> home earlier on fridays when I usually fire the kiln, but not at the
>> expense of having unpredictable or undesirable results from such a
>> fast firing.
>>
>> Any input much appreciated. thanks,
>>
>> jon
>>
>>
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>>
>>
>>
>>
>>
>>
>>
>> _____________________________________________________________________
>> _______________
>> You rock. That's why Blockbuster's offering you one month of
>> Blockbuster Total Access, No Cost.
>> http://tc.deals.yahoo.com/tc/blockbuster/text5.com
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>
>
> John Fulwood
> Kissimmee River Pottery
> One 8th St. #11
> Frenchtown, NJ. 08825
> http://www.kissimmeeriverpottery.com
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
Loren JOnes on sun 6 apr 08
I had great success using Vals schedule and forced air burners. The slow over night firing did allow the temp to be more even. A few times when things went wrong and the kiln shut off during the night I would try to restart in the morning and the firings never worked as well. My kilns were 36 cubic feet. One was a flat top and the other was an arch. Both had identical burner systems. Over night I had the damper at about
2 1/2 inches Gas at 1.8" on the flat top and .8 on the arch. I would adjust the air to achieve a fluttering blue flame. I did this weekly for 13 years and had great results! You will need to experiment with your kiln as to how much gas to use. Maybe start it at 10pm and go in at 4:30am and see how hot it got. Than adjust accordingly. I had a few times when it got hotter than I wanted but not often. Keep in mind I was firing student work and not work I was going to sell. Good Luck, Loren Jones
----- Original Message ----
From: jonathan byler
To: CLAYART@LSV.CERAMICS.ORG
Sent: Friday, April 4, 2008 5:26:39 PM
Subject: firing the gas kiln evenly.
I am having trouble getting our gas kiln to fire evenly early in the
firing. by the end, everything usually works out o.k., depending on
how it is stacked, and where the bagwall sits, it can get to less
than a half cone difference top to bottom. The evenness early in the
firing is an issue because the top goes through body reduction,
(start about ^012 - end about ^08) the bottom is just getting up to
^012, sometimes a little hotter. is there some secret to getting the
top and bottom to temp at about the same time early on? Do I need to
stagger the shelves more front to back? I usually try to get a layer
or two of taller pots towards the bottom to allow more flow through
that part of the kiln, which definitely seems to help the overall
evenness of the temp reached (^10).
I am trying to follow the firing schedule laid out in cushing's
handbook to some extent, but he raises the temp overnight to about
1652F (^010) and then does body reduction. our kiln has forced air
burners which don't really work so well at low settings, and I don't
like to start the firing other than using the pilots to dry
everything out well - about 191F when I get in in the morning, on the
off-chance that I won't make it in to work, and will get the kiln too
hot for the initial reduction, or some other mishap) It seems that
the length of his firing schedule is what permits the kiln to
presumably be more even in temperature top to bottom when he starts
reduction. I have noted that slowing the kiln in general seems to
promote more even heating within it, which makes me also wonder how
those of you who fire fast (say 4-6 hours) manage to get even
heating. I am all for speeding things up, as it means that I can go
home earlier on fridays when I usually fire the kiln, but not at the
expense of having unpredictable or undesirable results from such a
fast firing.
Any input much appreciated. thanks,
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
____________________________________________________________________________________
You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
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John Fulwood on sun 6 apr 08
Jon,
I do not know how much this will help but, here goes. First, what kind of kiln are you firing? sprung arch, flat top, updraft, downdraft, commercial or site built. The ideal shape is a square. If it is rectangular....taller than wide, you are going to have a hard time getting things to even out early on. My kiln is rect. I will not build a kiln I cannot stand up in so I deal with a little unevenness. The beauty of a reduction kiln is that it has it's own personality. If it is well built, you will have many firings to get to know it well. Heat rises and sometimes you just have to accept what you get and enjoy the ride. The fun part is that just when you think you have it figured out, the kiln gods will put you in your place and you get to start again. I love my job. I am loading my kiln now and I hope I remember the secrets. I guess I will find out on Tuesday when I unload.
If you lower your bag wall, you will get more heat in the bottom early on. You should also have some openings in the bag wall to allow some flame to be pulled into the bottom of the chamber. Maybe a target brick in the firebox to help break up the flame.
good luck,
John
al Message-----
>From: Loren JOnes
>Sent: Apr 6, 2008 12:07 PM
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: firing the gas kiln evenly.
>
>I had great success using Vals schedule and forced air burners. The slow over night firing did allow the temp to be more even. A few times when things went wrong and the kiln shut off during the night I would try to restart in the morning and the firings never worked as well. My kilns were 36 cubic feet. One was a flat top and the other was an arch. Both had identical burner systems. Over night I had the damper at about
>2 1/2 inches Gas at 1.8" on the flat top and .8 on the arch. I would adjust the air to achieve a fluttering blue flame. I did this weekly for 13 years and had great results! You will need to experiment with your kiln as to how much gas to use. Maybe start it at 10pm and go in at 4:30am and see how hot it got. Than adjust accordingly. I had a few times when it got hotter than I wanted but not often. Keep in mind I was firing student work and not work I was going to sell. Good Luck, Loren Jones
>----- Original Message ----
>From: jonathan byler
>To: CLAYART@LSV.CERAMICS.ORG
>Sent: Friday, April 4, 2008 5:26:39 PM
>Subject: firing the gas kiln evenly.
>
>I am having trouble getting our gas kiln to fire evenly early in the
>firing. by the end, everything usually works out o.k., depending on
>how it is stacked, and where the bagwall sits, it can get to less
>than a half cone difference top to bottom. The evenness early in the
>firing is an issue because the top goes through body reduction,
>(start about ^012 - end about ^08) the bottom is just getting up to
>^012, sometimes a little hotter. is there some secret to getting the
>top and bottom to temp at about the same time early on? Do I need to
>stagger the shelves more front to back? I usually try to get a layer
>or two of taller pots towards the bottom to allow more flow through
>that part of the kiln, which definitely seems to help the overall
>evenness of the temp reached (^10).
>
>I am trying to follow the firing schedule laid out in cushing's
>handbook to some extent, but he raises the temp overnight to about
>1652F (^010) and then does body reduction. our kiln has forced air
>burners which don't really work so well at low settings, and I don't
>like to start the firing other than using the pilots to dry
>everything out well - about 191F when I get in in the morning, on the
>off-chance that I won't make it in to work, and will get the kiln too
>hot for the initial reduction, or some other mishap) It seems that
>the length of his firing schedule is what permits the kiln to
>presumably be more even in temperature top to bottom when he starts
>reduction. I have noted that slowing the kiln in general seems to
>promote more even heating within it, which makes me also wonder how
>those of you who fire fast (say 4-6 hours) manage to get even
>heating. I am all for speeding things up, as it means that I can go
>home earlier on fridays when I usually fire the kiln, but not at the
>expense of having unpredictable or undesirable results from such a
>fast firing.
>
>Any input much appreciated. thanks,
>
>jon
>
>
>jon byler
>3-D Building Coordinator
>Art Department
>Auburn University, AL 36849
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
>
>
>
>
>
>
> ____________________________________________________________________________________
>You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
>http://tc.deals.yahoo.com/tc/blockbuster/text5.com
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
John Fulwood
Kissimmee River Pottery
One 8th St. #11
Frenchtown, NJ. 08825
http://www.kissimmeeriverpottery.com
John Fulwood on mon 7 apr 08
Jon,
The best thing you can do at this point is call Jim Bailey and ask his advice. He is very helpful and since you have one of his kilns, I am sure he will do all he can to help you out.
john
-----Original Message-----
>From: jonathan byler
>Sent: Apr 7, 2008 12:37 AM
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: firing the gas kiln evenly.
>
>The kiln in question is a bailey shuttle pro32, sprung arch, down
>draft, forced air (power burner), natural gas. I added an extra
>brick to lengthen the bag wall this past firing, and I will try
>spacing them apart a little in the next. There is a problem with the
>bottom in the back initially getting too hot, which means that those
>extreme back edge areas go through body reduction temperatures
>earlier than the rest of the kiln, which keeps them from getting that
>lovely warm color that the other pots get. So I will try to space a
>little farther apart towards the front of the kiln. The bagwall, by
>the way, extends about 6 bricks from the burner port and has a target
>brick directly at the end. I put some cones down in the bottom at
>the center-back area, and they only came down to a softish cone 9
>with the ten cone at 2-3 o'clock, whereas the top front had the ten
>touching, and the eleven about 2 o'clock, and the bottom front the
>ten was just barely touching. I think If I move the bagwall too far
>forward, that the bottom back will suffer yet more in terms of under
>firing. By the way, we did fire a small kiln god with this load of
>pots in order to ward of the bad spirits. Although I am loathe to
>believe in such things, don't tell that to the kiln god!
>
>I am going to try the slow heat overnight thing, but I hope that does
>not become a regular affair. The pilots on this kiln put out a much
>smaller flame at maximum power than the ones on the larger kiln,
>despite being the same design. I need to compare orifices and
>determine why this is, as we could get a much better start if the
>pilots could pull their own weight. I have also thought about
>setting up the controller on that kiln to do a hold/soak program, the
>same as our other, larger, bailey gas kiln can do. It should just be
>a matter of a few switches and relays, but I may have to change how
>the pilots get their gas supply too.
>
>
>jon byler
>3-D Building Coordinator
>Art Department
>Auburn University, AL 36849
>
>On Apr 6, 2008, at 4:06 PM, John Fulwood wrote:
>
>> Jon,
>>
>> I do not know how much this will help but, here goes. First, what
>> kind of kiln are you firing? sprung arch, flat top, updraft,
>> downdraft, commercial or site built. The ideal shape is a square.
>> If it is rectangular....taller than wide, you are going to have a
>> hard time getting things to even out early on. My kiln is rect. I
>> will not build a kiln I cannot stand up in so I deal with a little
>> unevenness. The beauty of a reduction kiln is that it has it's own
>> personality. If it is well built, you will have many firings to get
>> to know it well. Heat rises and sometimes you just have to accept
>> what you get and enjoy the ride. The fun part is that just when you
>> think you have it figured out, the kiln gods will put you in your
>> place and you get to start again. I love my job. I am loading my
>> kiln now and I hope I remember the secrets. I guess I will find out
>> on Tuesday when I unload.
>>
>> If you lower your bag wall, you will get more heat in the bottom
>> early on. You should also have some openings in the bag wall to
>> allow some flame to be pulled into the bottom of the chamber. Maybe
>> a target brick in the firebox to help break up the flame.
>>
>>
>> good luck,
>>
>> John
>>
>>
>>
>> al Message-----
>>> From: Loren JOnes
>>> Sent: Apr 6, 2008 12:07 PM
>>> To: CLAYART@LSV.CERAMICS.ORG
>>> Subject: Re: firing the gas kiln evenly.
>>>
>>> I had great success using Vals schedule and forced air burners.
>>> The slow over night firing did allow the temp to be more even. A
>>> few times when things went wrong and the kiln shut off during the
>>> night I would try to restart in the morning and the firings never
>>> worked as well. My kilns were 36 cubic feet. One was a flat top
>>> and the other was an arch. Both had identical burner systems. Over
>>> night I had the damper at about
>>> 2 1/2 inches Gas at 1.8" on the flat top and .8 on the arch. I
>>> would adjust the air to achieve a fluttering blue flame. I did
>>> this weekly for 13 years and had great results! You will need to
>>> experiment with your kiln as to how much gas to use. Maybe start
>>> it at 10pm and go in at 4:30am and see how hot it got. Than adjust
>>> accordingly. I had a few times when it got hotter than I wanted
>>> but not often. Keep in mind I was firing student work and not work
>>> I was going to sell. Good Luck, Loren Jones
>>> ----- Original Message ----
>>> From: jonathan byler
>>> To: CLAYART@LSV.CERAMICS.ORG
>>> Sent: Friday, April 4, 2008 5:26:39 PM
>>> Subject: firing the gas kiln evenly.
>>>
>>> I am having trouble getting our gas kiln to fire evenly early in the
>>> firing. by the end, everything usually works out o.k., depending on
>>> how it is stacked, and where the bagwall sits, it can get to less
>>> than a half cone difference top to bottom. The evenness early in the
>>> firing is an issue because the top goes through body reduction,
>>> (start about ^012 - end about ^08) the bottom is just getting up to
>>> ^012, sometimes a little hotter. is there some secret to getting the
>>> top and bottom to temp at about the same time early on? Do I need to
>>> stagger the shelves more front to back? I usually try to get a layer
>>> or two of taller pots towards the bottom to allow more flow through
>>> that part of the kiln, which definitely seems to help the overall
>>> evenness of the temp reached (^10).
>>>
>>> I am trying to follow the firing schedule laid out in cushing's
>>> handbook to some extent, but he raises the temp overnight to about
>>> 1652F (^010) and then does body reduction. our kiln has forced air
>>> burners which don't really work so well at low settings, and I don't
>>> like to start the firing other than using the pilots to dry
>>> everything out well - about 191F when I get in in the morning, on the
>>> off-chance that I won't make it in to work, and will get the kiln too
>>> hot for the initial reduction, or some other mishap) It seems that
>>> the length of his firing schedule is what permits the kiln to
>>> presumably be more even in temperature top to bottom when he starts
>>> reduction. I have noted that slowing the kiln in general seems to
>>> promote more even heating within it, which makes me also wonder how
>>> those of you who fire fast (say 4-6 hours) manage to get even
>>> heating. I am all for speeding things up, as it means that I can go
>>> home earlier on fridays when I usually fire the kiln, but not at the
>>> expense of having unpredictable or undesirable results from such a
>>> fast firing.
>>>
>>> Any input much appreciated. thanks,
>>>
>>> jon
>>>
>>>
>>> jon byler
>>> 3-D Building Coordinator
>>> Art Department
>>> Auburn University, AL 36849
>>>
>>> _____________________________________________________________________
>>> _________
>>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>>
>>> You may look at the archives for the list, post messages, change your
>>> subscription settings or unsubscribe/leave the list here: http://
>>> www.acers.org/cic/clayart/
>>>
>>> Moderator of the list is Mel Jacobson who may be reached at
>>> melpots2@visi.com
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _____________________________________________________________________
>>> _______________
>>> You rock. That's why Blockbuster's offering you one month of
>>> Blockbuster Total Access, No Cost.
>>> http://tc.deals.yahoo.com/tc/blockbuster/text5.com
>>>
>>> _____________________________________________________________________
>>> _________
>>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>>
>>> You may look at the archives for the list, post messages, change your
>>> subscription settings or unsubscribe/leave the list here: http://
>>> www.acers.org/cic/clayart/
>>>
>>> Moderator of the list is Mel Jacobson who may be reached at
>>> melpots2@visi.com
>>
>>
>> John Fulwood
>> Kissimmee River Pottery
>> One 8th St. #11
>> Frenchtown, NJ. 08825
>> http://www.kissimmeeriverpottery.com
>>
>> ______________________________________________________________________
>> ________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
John Fulwood
Kissimmee River Pottery
One 8th St. #11
Frenchtown, NJ. 08825
http://www.kissimmeeriverpottery.com
Loren JOnes on mon 7 apr 08
Your On the right track! It took me awhile to tune my kilns so that they fired evenly. I still had a cool spot at the bottom back of the flat top kiln. I put a deflection brick about 10 inches or so from the port turned at an angle to hopefully get the flame to go to that spot. this worked to some degree. Keep adjusting. Think of the flame as water, move it to where you need it. It will always take the path of least resistance out of the kiln.
----- Original Message ----
From: jonathan byler
To: CLAYART@LSV.CERAMICS.ORG
Sent: Sunday, April 6, 2008 10:37:40 PM
Subject: Re: firing the gas kiln evenly.
The kiln in question is a bailey shuttle pro32, sprung arch, down
draft, forced air (power burner), natural gas. I added an extra
brick to lengthen the bag wall this past firing, and I will try
spacing them apart a little in the next. There is a problem with the
bottom in the back initially getting too hot, which means that those
extreme back edge areas go through body reduction temperatures
earlier than the rest of the kiln, which keeps them from getting that
lovely warm color that the other pots get. So I will try to space a
little farther apart towards the front of the kiln. The bagwall, by
the way, extends about 6 bricks from the burner port and has a target
brick directly at the end. I put some cones down in the bottom at
the center-back area, and they only came down to a softish cone 9
with the ten cone at 2-3 o'clock, whereas the top front had the ten
touching, and the eleven about 2 o'clock, and the bottom front the
ten was just barely touching. I think If I move the bagwall too far
forward, that the bottom back will suffer yet more in terms of under
firing. By the way, we did fire a small kiln god with this load of
pots in order to ward of the bad spirits. Although I am loathe to
believe in such things, don't tell that to the kiln god!
I am going to try the slow heat overnight thing, but I hope that does
not become a regular affair. The pilots on this kiln put out a much
smaller flame at maximum power than the ones on the larger kiln,
despite being the same design. I need to compare orifices and
determine why this is, as we could get a much better start if the
pilots could pull their own weight. I have also thought about
setting up the controller on that kiln to do a hold/soak program, the
same as our other, larger, bailey gas kiln can do. It should just be
a matter of a few switches and relays, but I may have to change how
the pilots get their gas supply too.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 6, 2008, at 4:06 PM, John Fulwood wrote:
> Jon,
>
> I do not know how much this will help but, here goes. First, what
> kind of kiln are you firing? sprung arch, flat top, updraft,
> downdraft, commercial or site built. The ideal shape is a square.
> If it is rectangular....taller than wide, you are going to have a
> hard time getting things to even out early on. My kiln is rect. I
> will not build a kiln I cannot stand up in so I deal with a little
> unevenness. The beauty of a reduction kiln is that it has it's own
> personality. If it is well built, you will have many firings to get
> to know it well. Heat rises and sometimes you just have to accept
> what you get and enjoy the ride. The fun part is that just when you
> think you have it figured out, the kiln gods will put you in your
> place and you get to start again. I love my job. I am loading my
> kiln now and I hope I remember the secrets. I guess I will find out
> on Tuesday when I unload.
>
> If you lower your bag wall, you will get more heat in the bottom
> early on. You should also have some openings in the bag wall to
> allow some flame to be pulled into the bottom of the chamber. Maybe
> a target brick in the firebox to help break up the flame.
>
>
> good luck,
>
> John
>
>
>
> al Message-----
>> From: Loren JOnes
>> Sent: Apr 6, 2008 12:07 PM
>> To: CLAYART@LSV.CERAMICS.ORG
>> Subject: Re: firing the gas kiln evenly.
>>
>> I had great success using Vals schedule and forced air burners.
>> The slow over night firing did allow the temp to be more even. A
>> few times when things went wrong and the kiln shut off during the
>> night I would try to restart in the morning and the firings never
>> worked as well. My kilns were 36 cubic feet. One was a flat top
>> and the other was an arch. Both had identical burner systems. Over
>> night I had the damper at about
>> 2 1/2 inches Gas at 1.8" on the flat top and .8 on the arch. I
>> would adjust the air to achieve a fluttering blue flame. I did
>> this weekly for 13 years and had great results! You will need to
>> experiment with your kiln as to how much gas to use. Maybe start
>> it at 10pm and go in at 4:30am and see how hot it got. Than adjust
>> accordingly. I had a few times when it got hotter than I wanted
>> but not often. Keep in mind I was firing student work and not work
>> I was going to sell. Good Luck, Loren Jones
>> ----- Original Message ----
>> From: jonathan byler
>> To: CLAYART@LSV.CERAMICS.ORG
>> Sent: Friday, April 4, 2008 5:26:39 PM
>> Subject: firing the gas kiln evenly.
>>
>> I am having trouble getting our gas kiln to fire evenly early in the
>> firing. by the end, everything usually works out o.k., depending on
>> how it is stacked, and where the bagwall sits, it can get to less
>> than a half cone difference top to bottom. The evenness early in the
>> firing is an issue because the top goes through body reduction,
>> (start about ^012 - end about ^08) the bottom is just getting up to
>> ^012, sometimes a little hotter. is there some secret to getting the
>> top and bottom to temp at about the same time early on? Do I need to
>> stagger the shelves more front to back? I usually try to get a layer
>> or two of taller pots towards the bottom to allow more flow through
>> that part of the kiln, which definitely seems to help the overall
>> evenness of the temp reached (^10).
>>
>> I am trying to follow the firing schedule laid out in cushing's
>> handbook to some extent, but he raises the temp overnight to about
>> 1652F (^010) and then does body reduction. our kiln has forced air
>> burners which don't really work so well at low settings, and I don't
>> like to start the firing other than using the pilots to dry
>> everything out well - about 191F when I get in in the morning, on the
>> off-chance that I won't make it in to work, and will get the kiln too
>> hot for the initial reduction, or some other mishap) It seems that
>> the length of his firing schedule is what permits the kiln to
>> presumably be more even in temperature top to bottom when he starts
>> reduction. I have noted that slowing the kiln in general seems to
>> promote more even heating within it, which makes me also wonder how
>> those of you who fire fast (say 4-6 hours) manage to get even
>> heating. I am all for speeding things up, as it means that I can go
>> home earlier on fridays when I usually fire the kiln, but not at the
>> expense of having unpredictable or undesirable results from such a
>> fast firing.
>>
>> Any input much appreciated. thanks,
>>
>> jon
>>
>>
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>>
>>
>>
>>
>>
>>
>>
>> _____________________________________________________________________
>> _______________
>> You rock. That's why Blockbuster's offering you one month of
>> Blockbuster Total Access, No Cost.
>> http://tc.deals.yahoo.com/tc/blockbuster/text5.com
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>
>
> John Fulwood
> Kissimmee River Pottery
> One 8th St. #11
> Frenchtown, NJ. 08825
> http://www.kissimmeeriverpottery.com
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
____________________________________________________________________________________
You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
http://tc.deals.yahoo.com/tc/blockbuster/text5.com
Larry Kruzan on mon 7 apr 08
Hi Jonathan,
There are LOTS of folks here that have many more years of firing a gas kiln
than I, but I'll tell you how I do it. No bagwall - tried one when I first
built my gas kiln and had the same sort of problems you describe and worse.
I do have a target brick about 3 feet from the burner port - it is a single
hard brick turned edge on to the flame.
My 100cf kiln has a cart that is 4.5 feet long, 3.5 feet wide and the pots
closest to the burner ports and flue end are always 1/2 to 1 cone cooler on
the bottom shelf. Loading does not seem to change this and it has been this
way since the first firing - the rest of the kiln is within 1/2 cone
everywhere.
I did not see your firing schedule but it can have a real affect on how even
the kiln is. My practice is to move quickly to 600, then slow a little to
even it out, speed up again to 1100, slow down again for a while, hit hard
to just below reduction and when it evens out I start a heavy reduction - I
don't touch the fuel after this, if it stalls I increase the air or adjust
the damper to maintain temp climb. I have posted my firing schedule before
and it is in the archives if you would like to see it.
In those areas where I know it will be cool I put glazes that will not be
affected by being a little cool - typically my cobalt blues (uggg! They will
be blue no matter what!). The end corner of the flame channel can be a
little hot (1/2 cone at times) so I put glazes that are good from 10-12 in
that spot.
If this all sounds like I have a problem I'm willing to work with instead of
fixing, you might be right - I've been married for 31 years and have learned
that there are times to stand up and times to shut up. Somewhere in there I
learned all I know about kilns.
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of jonathan byler
Sent: Sunday, April 06, 2008 11:38 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: [CLAYART] firing the gas kiln evenly.
The kiln in question is a bailey shuttle pro32, sprung arch, down
draft, forced air (power burner), natural gas. I added an extra
brick to lengthen the bag wall this past firing, and I will try
spacing them apart a little in the next. There is a problem with the
bottom in the back initially getting too hot, which means that those
extreme back edge areas go through body reduction temperatures
earlier than the rest of the kiln, which keeps them from getting that
lovely warm color that the other pots get. So I will try to space a
little farther apart towards the front of the kiln. The bagwall, by
the way, extends about 6 bricks from the burner port and has a target
brick directly at the end. I put some cones down in the bottom at
the center-back area, and they only came down to a softish cone 9
with the ten cone at 2-3 o'clock, whereas the top front had the ten
touching, and the eleven about 2 o'clock, and the bottom front the
ten was just barely touching. I think If I move the bagwall too far
forward, that the bottom back will suffer yet more in terms of under
firing. By the way, we did fire a small kiln god with this load of
pots in order to ward of the bad spirits. Although I am loathe to
believe in such things, don't tell that to the kiln god!
I am going to try the slow heat overnight thing, but I hope that does
not become a regular affair. The pilots on this kiln put out a much
smaller flame at maximum power than the ones on the larger kiln,
despite being the same design. I need to compare orifices and
determine why this is, as we could get a much better start if the
pilots could pull their own weight. I have also thought about
setting up the controller on that kiln to do a hold/soak program, the
same as our other, larger, bailey gas kiln can do. It should just be
a matter of a few switches and relays, but I may have to change how
the pilots get their gas supply too.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 6, 2008, at 4:06 PM, John Fulwood wrote:
> Jon,
>
> I do not know how much this will help but, here goes. First, what
> kind of kiln are you firing? sprung arch, flat top, updraft,
> downdraft, commercial or site built. The ideal shape is a square.
> If it is rectangular....taller than wide, you are going to have a
> hard time getting things to even out early on. My kiln is rect. I
> will not build a kiln I cannot stand up in so I deal with a little
> unevenness. The beauty of a reduction kiln is that it has it's own
> personality. If it is well built, you will have many firings to get
> to know it well. Heat rises and sometimes you just have to accept
> what you get and enjoy the ride. The fun part is that just when you
> think you have it figured out, the kiln gods will put you in your
> place and you get to start again. I love my job. I am loading my
> kiln now and I hope I remember the secrets. I guess I will find out
> on Tuesday when I unload.
>
> If you lower your bag wall, you will get more heat in the bottom
> early on. You should also have some openings in the bag wall to
> allow some flame to be pulled into the bottom of the chamber. Maybe
> a target brick in the firebox to help break up the flame.
>
>
> good luck,
>
> John
>
>
>
> al Message-----
>> From: Loren JOnes
>> Sent: Apr 6, 2008 12:07 PM
>> To: CLAYART@LSV.CERAMICS.ORG
>> Subject: Re: firing the gas kiln evenly.
>>
>> I had great success using Vals schedule and forced air burners.
>> The slow over night firing did allow the temp to be more even. A
>> few times when things went wrong and the kiln shut off during the
>> night I would try to restart in the morning and the firings never
>> worked as well. My kilns were 36 cubic feet. One was a flat top
>> and the other was an arch. Both had identical burner systems. Over
>> night I had the damper at about
>> 2 1/2 inches Gas at 1.8" on the flat top and .8 on the arch. I
>> would adjust the air to achieve a fluttering blue flame. I did
>> this weekly for 13 years and had great results! You will need to
>> experiment with your kiln as to how much gas to use. Maybe start
>> it at 10pm and go in at 4:30am and see how hot it got. Than adjust
>> accordingly. I had a few times when it got hotter than I wanted
>> but not often. Keep in mind I was firing student work and not work
>> I was going to sell. Good Luck, Loren Jones
>> ----- Original Message ----
>> From: jonathan byler
>> To: CLAYART@LSV.CERAMICS.ORG
>> Sent: Friday, April 4, 2008 5:26:39 PM
>> Subject: firing the gas kiln evenly.
>>
>> I am having trouble getting our gas kiln to fire evenly early in the
>> firing. by the end, everything usually works out o.k., depending on
>> how it is stacked, and where the bagwall sits, it can get to less
>> than a half cone difference top to bottom. The evenness early in the
>> firing is an issue because the top goes through body reduction,
>> (start about ^012 - end about ^08) the bottom is just getting up to
>> ^012, sometimes a little hotter. is there some secret to getting the
>> top and bottom to temp at about the same time early on? Do I need to
>> stagger the shelves more front to back? I usually try to get a layer
>> or two of taller pots towards the bottom to allow more flow through
>> that part of the kiln, which definitely seems to help the overall
>> evenness of the temp reached (^10).
>>
>> I am trying to follow the firing schedule laid out in cushing's
>> handbook to some extent, but he raises the temp overnight to about
>> 1652F (^010) and then does body reduction. our kiln has forced air
>> burners which don't really work so well at low settings, and I don't
>> like to start the firing other than using the pilots to dry
>> everything out well - about 191F when I get in in the morning, on the
>> off-chance that I won't make it in to work, and will get the kiln too
>> hot for the initial reduction, or some other mishap) It seems that
>> the length of his firing schedule is what permits the kiln to
>> presumably be more even in temperature top to bottom when he starts
>> reduction. I have noted that slowing the kiln in general seems to
>> promote more even heating within it, which makes me also wonder how
>> those of you who fire fast (say 4-6 hours) manage to get even
>> heating. I am all for speeding things up, as it means that I can go
>> home earlier on fridays when I usually fire the kiln, but not at the
>> expense of having unpredictable or undesirable results from such a
>> fast firing.
>>
>> Any input much appreciated. thanks,
>>
>> jon
>>
>>
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>>
>>
>>
>>
>>
>>
>>
>> _____________________________________________________________________
>> _______________
>> You rock. That's why Blockbuster's offering you one month of
>> Blockbuster Total Access, No Cost.
>> http://tc.deals.yahoo.com/tc/blockbuster/text5.com
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>
>
> John Fulwood
> Kissimmee River Pottery
> One 8th St. #11
> Frenchtown, NJ. 08825
> http://www.kissimmeeriverpottery.com
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
____________________________________________________________________________
__
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here:
http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots2@visi.com
| |
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