Craig Martell on thu 11 sep 03
Hi:
I pack the reduction kiln very tight. It fires very well with little
difference in temp or atmospheric needs. It cools slower, which I want,
and I also have more pots to sell. I pack my salt kiln a bit looser to
allow area for the salt vapor to move between the pots.
I think that a well designed kiln has the extra muscle to handle larger
thermal mass if necessary.
regards, Craig Martell Hopewell, Oregon
Lori Leary on thu 11 sep 03
Thanks for the speedy replies.
From the responses thus far, I know I have not made it clear what I mean by
"loose" pack. I am talking about packing the kiln in such a manner that
allows for even reduction and a kiln that is consistent in temp in all if
not most areas. I do not mean half or three-quarter full firings due to low
production. When I say tight, I mean exceedingly tight; enough to cause
spotty reduction, little reduction, and uneven temp.
I have learned from mel and Nils not to pack the kiln too tightly. I am not
a recreational potter, and have not been one for quite some time, so please
don't make any assumptions. In my MFT, I was able to fire *efficiently* and
with good results with a not-too-tight pack. Fast on the way up, with
burner assisted cooling on the way down.
Just wanted to clarify things,
Lori
Stephani Stephenson on thu 11 sep 03
Lori
The main advice I would give on the updraft is not to make
the lowest shelves too low .
I.e. no 2" stilts on the bottom, use at least 4", or 6" or
8".
The bottom part of the kiln will tend to be the coolest. Of
course this makes it ideal for wide bottom plates and
platters which you want to fire without warping , etc. but
if that first shelf is too low, that part of the kiln will
have difficulty reaching temperature.
so if you have low items on the bottom, give them at least a
little little headroom.
Also I use to make sure that the back lowest shelf was at a
different height than the forward lowest shelf, to further
ensure circulation....
when firing you will want to make sure you are getting some
back pressure at the lowest peep, to ensure the heat is
circulating back down to lowest part of the kiln before
circulating and re exiting through the top damper.
I use to pack densely but I would alternate the heights of
back stack of shelves and front stack, and continue doing
that all the way to the top if possible, thinking in terms
of how heat would circulate.
I use to really like the Alpine updrafts, once I got to know
them. I liked the control with the power burners, with
controls for both air and gas. I got some beautiful
firings, oxidation and reduction, at cone 6 and at cone 10.
Stephani Stephenson
steph@alchemiestudio.com
Lori Leary on thu 11 sep 03
I am wondering if all of you might help me out. I am very interested in =
hearing people's preferences in how they load their reduction =
kilns....(loose pack vs. a tight pack) and why.
Here's the scoop:
I am attending grad school where the gas kilns are Alpines (a challenge =
in itself, in my view) One is an old updraft and the other is a newer =
downdraft. I am used to firing a lovely Minnesota Flat Top I built =
(with the Mayor's help) when I lived in South Carolina. So I am having =
to make adjustments.....
Since I have been in school, I have been trying to convince my teacher =
of the benefits of looser packing....but to no avail. He says he is of =
the "Old School"..that a kiln has to be packed as tight as possible. =20
Most of my work has been saggar and pit fired, so this has not been much =
of an issue for me. I never had enough high fire work to load and fire =
my own kiln load ( although I have fired the downdraft Alpine several =
times without loading it myself...another story!) The limited ^10 work =
that I have done has been somewhat disappointing, though...making me =
pine for my old MFT. This year, I have been making more high fire work =
and plan to load and fire the down draft Alpine myself in in the next =
couple of weeks. I know the proof is in the pudding, so hopefully I =
will have good results that will demonstrate my theory. In the =
meantime, can you guys help me out with a little evidence, anecdotal or =
scientific?
By the way, my professor has a wood kiln at his house that I have helped =
fire twice...We have never been able reach temp, I am not sure it ever =
has. I think a large part of the problem has been the tight packing.=20
Thanks for the help,
Lori L.
Anywhere, USA
Kathi LeSueur on thu 11 sep 03
lleary@EPIX.NET wrote:
>I am wondering if all of you might help me out. I am very interested in hearing people's preferences in how they load their reduction kilns....(loose pack vs. a tight pack) and why......
>
>Here's the scoop:
>I am attending grad school where the gas kilns are Alpines......
>Since I have been in school, I have been trying to convince my teacher of the benefits of looser packing....but to no avail. He says he is of the "Old School"..that a kiln has to be packed as tight as possible. >>
>
>I fire my kiln as tightly packed as possible. I make lots of small items that can be tucked in "nooks and crannies". Besides increasing the dollar volume of each firing, the tight mass of work cools slower which allows the color to develop better in my glazes. Whenever I've been short of those little pots and had a looser pack the color is not nearly as nice and the kiln cools quicker.
>
>Kathi
>
>
>
>
Hank Murrow on thu 11 sep 03
On Thursday, September 11, 2003, at 03:59 PM, Lori Leary wrote:
> I am wondering if all of you might help me out. I am very interested
> in hearing people's preferences in how they load their reduction
> kilns....(loose pack vs. a tight pack) and why.
>
> By the way, my professor has a wood kiln at his house that I have
> helped fire twice...We have never been able reach temp, I am not sure
> it ever has. I think a large part of the problem has been the tight
> packing.
>
Dear Lori,
The effects of close or loose packing in wood fired kilns is a more
critical one, as ash and flame must flow through the wares. The issue
is pretty much moot with a typical gas studio kiln. I pack my Doorless
Fiber kiln very tightly from time to time, but have been known to fire
it (28 cuft) with only a dozen teabowls in it. I wanted that
information, and other than a shorter time to maturity, I noticed very
little difference between the two extremes.
Hoping you achieve clarity, Hank
Ellen Dreksler on thu 11 sep 03
>
> From: Kathi LeSueur
> Date: 2003/09/11 Thu PM 08:09:24 PDT
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: packing the kiln : a debate
>
> lleary@EPIX.NET wrote:
>
> >I am wondering if all of you might help me out. I am very interested in hearing people's preferences in how they load their reduction kilns....(loose pack vs. a tight pack) and why......
> >
> >Here's the scoop:
> >I am attending grad school where the gas kilns are Alpines......
> >Since I have been in school, I have been trying to convince my teacher of the benefits of looser packing....but to no avail. He says he is of the "Old School"..that a kiln has to be packed as tight as possible. >>
> >
>
> >I fire my kiln as tightly packed as possible. I make lots of small items that can be tucked in "nooks and crannies". Besides increasing the dollar volume of each firing, the tight mass of work cools slower which allows the color to develop better in my glazes. Whenever I've been short of those little pots and had a looser pack the color is not nearly as nice and the kiln cools quicker.
> >
> >Kathi
> >
> >
> >
> >
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
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>
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>
Des & Jan Howard on fri 12 sep 03
Oops! I hit "Send" not "Save"
Addendum:
Hopefully your teacher has done the hard yards in pottery.
Ask him why he prefers a tight pack & listen to the answer.
Des
Des & Jan Howard wrote:
> We equate loosely packed kilns with institutions & recreational potters.
>
> Des
>
> Lori Leary wrote:
>
> > I am wondering if all of you might help me out. I am very interested in hearing people's preferences in how they load their reduction kilns....(loose pack vs. a tight pack) and why.
> >
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
Marcia Selsor on fri 12 sep 03
While teaching ceramics for 25 years and firing gas kilns, I always
packed the kilns as tight as possible. Pieces were 2 fingers from the
back wall and 1/4" apart. Reduction always seemed better in a tight
kiln. We fired a lot..sometimes four times/week in the two gas kilns
that I built...a big car kiln (60 cu.ft) and a smaller sprung arch kiln
(36 cu.ft) so that is a lot of experience with tight kilns. I fired
Alpines in grad school also. Tight kilns fired better for those updrafts
too. Salt kilns are a different story but not much different. Tight as
possible. I have found soda in a vapor seems to circulate better than
dry salt introduced into the kiln.
Marcia Selsor
Tuscany 2004
http://home.bresnan.net/~m.selsor/Tuscany2004.html
Marcia Selsor on fri 12 sep 03
Dear Lori,
The big wood kiln and the smaller soda/wood kiln at the Bray are both
packed as tight as can be. They reach temperature with a lot of work.
The big wood kiln took 5 days of firing.
Marcia
> On Thursday, September 11, 2003, at 03:59 PM, Lori Leary wrote:
>
>> I am wondering if all of you might help me out. I am very interested
>> in hearing people's preferences in how they load their reduction
>> kilns....(loose pack vs. a tight pack) and why.
>>
>> By the way, my professor has a wood kiln at his house that I have
>> helped fire twice...We have never been able reach temp, I am not sure
>> it ever has. I think a large part of the problem has been the tight
>> packing.
Tuscany 2004
http://home.bresnan.net/~m.selsor/Tuscany2004.html
Lori Leary on fri 12 sep 03
Hi Des,
Yes, my professor has done the hard yards in pottery, as have I (going on 16
years now). I have asked him why, knowing what his answer would be; I used
to believe the same thing. But my experience as a potter, and as owner of a
teaching studio has shown me otherwise.
I stand by my assertion that "loose" glaze packing leads to fast, efficient,
firing with evenly reduced ware. With burner assisted cooling on the way
down, I have had fine results for Cu Reds, carbon Trap shinos, and
adventurine glazes.
Regards,
Lori
Des wrote:
> Hopefully your teacher has done the hard yards in pottery.
> Ask him why he prefers a tight pack & listen to the answer.
> > We equate loosely packed kilns with institutions & recreational potters.
Dapogny.Gail on fri 12 sep 03
Lori,
At our Guild, we have a tendency to pack tightly, sometimes extremely
tightly. I have noticed that, in those extreme cases, reduction and heat
are a bit uneven----i.e. more so than usual in a 94 cubic ft kiln. This is
especially true when things are quite uniform in size, and circulation is
not so hot (so to speak!).
In the moderately tight firings, things seem to go well, and, as Kathi L
mentioned with her kiln, the cooling is not as fast as it would be in a
loosely stacked kiln (which of course is not what you are talking about
anyway).
Check for both heat and reduction in various parts of the kiln, high and
low ---but you already know all this.
Cheers to the "land of gloom and doom" --- hope all is well.
--Gail
>>From the responses thus far, I know I have not made it clear what I mean by
>"loose" pack. I am talking about packing the kiln in such a manner that
>allows for even reduction and a kiln that is consistent in temp in all if
>not most areas. I do not mean half or three-quarter full firings due to low
>production. When I say tight, I mean exceedingly tight; enough to cause
>spotty reduction, little reduction, and uneven temp.
Hank Murrow on fri 12 sep 03
Nice post, Craig..........and nice to have you back in the mix. Hank
On Thursday, September 11, 2003, at 08:33 PM, Craig Martell wrote:
> Hi:
>
> I pack the reduction kiln very tight. It fires very well with little
> difference in temp or atmospheric needs. It cools slower, which I
> want,
> and I also have more pots to sell. I pack my salt kiln a bit looser to
> allow area for the salt vapor to move between the pots.
>
> I think that a well designed kiln has the extra muscle to handle larger
> thermal mass if necessary.
Sue Leabu on fri 12 sep 03
On Thu, 11 Sep 2003 18:59:03 -0400, Lori Leary wrote:
>By the way, my professor has a wood kiln at his house that I have helped
fire twice...We have never been able reach temp, I am not sure it ever
has. I think a large part of the problem has been the tight packing.
>
Hi Lori,
Had a discussion about this last night with the new instructor of the
anagama class I've been involved in for three years. Our anagama will reach
temp easily in the front and middle, but, the rear third of the kiln has
always been difficult to fire off; more common for it to be underfired. Her
observation (having seen the last three or four loadings) is that it's been
packed way too tight, and she wants to loosen it up when we load in two
weeks. I think she's right on the money, and am anxious to see if we have
an easier time getting the back to temp.
Sue
Kalamazoo, MI
Des & Jan Howard on fri 12 sep 03
Lori
The economics (fuel & labour) of firing kilns has always dictated
a tight pack for us. This has applied to all of our kilns over the years,
electric, wood, oil, inspirated & forced air gas.
Any areas of the kilns that have predictable hotter/colder spots
have appropriate glazes used in these areas.
When from necessity some areas have been loosely packed
the general result is unsatisfactory.
We equate loosely packed kilns with institutions & recreational potters.
Des
Lori Leary wrote:
> I am wondering if all of you might help me out. I am very interested in hearing people's preferences in how they load their reduction kilns....(loose pack vs. a tight pack) and why.
>
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
Janet Kaiser on sat 13 sep 03
Please could everyone entering this debate state clearly what
exactly they mean by "loose" and what kiln type / size / fuel
they are using at what temperature range? The comparisons are not
going to be much help to anyone otherwise. Especially when taken
out of context later (as single stand-alone mail in the
archives).
Indeed, I think it is debatable what help Lori will specifically
glean from what anyone says, because all kilns are so different
plus all the other variables like timing, the ware being fired,
the glaze and all. BTW Lori, can you tell why the kiln is not
reaching temperature? Are there time restrictions at play beside
what you have already said?
And what about the temperature reduction is started at? I was
coincidentally talking to John Ambrose who makes the most
gorgeous ox blood / sang beouf high-fired stoneware pots and
platters yesterday and he said his "secret" (a guaranteed method
learned from a Swedish potter years ago) was to start reduction
at 840-850 =B0C. His firings last approx. eight hours to top
temperature and he said that this was critical for his glazes to
succeed. He did mention a specific temperature which must not be
exceeded, but sorry... Leaping senility has intervened and my
short term memory is not up to the task :-)
Your mileage may vary as they say...
Sincerely
Janet Kaiser - who was taught to pack "relatively close". Learned
the hard way, especially following several plucked pots!
***********************************************************
The top posted mail was sent by Janet Kaiser
The Chapel of Art : Capel Celfyddyd
8 Marine Crescent : Criccieth : Wales : UK
Centre of Excellence for The Arts
Home of The International Potters' Path
Tel: ++44 (01766) 523570 http://www.the-coa.org.uk
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John Baymore on sat 13 sep 03
=46rom the responses thus far, I know I have not made it clear what I mea=
n by
"loose" pack. I am talking about packing the kiln in such a manner that
allows for even reduction and a kiln that is consistent in temp in all if=
not most areas. I do not mean half or three-quarter full firings due to
low
production. When I say tight, I mean exceedingly tight; enough to cause=
spotty reduction, little reduction, and uneven temp.
Lori,
Stacking relates greatly to the kiln being stacked .
By that I mean first of all that if a kiln is well designed... it has a
wide latitude in it's response to the nature of the stacking. The second=
thought relating to that first statement is looking at the function of th=
e
kiln itself. Meaning if the kiln itself is the "inducer " of a lot of th=
e
combustion air flow, then the stacking will have a greater effect on the
firing results. And thirdly, one has to consider the decorative impacts
that the direction and volume of gas flow (burning combustion gases and
byproducts) has on the particular type of wares (salt kiln, soda kiln, wo=
od
kiln).
A gas kiln with (decent potter level of technology) forced air burners th=
at
HAS to be stacked a certain way to prevent spotty reduction, little
reduction, or uneven temperature likely has some design problems or some
operator problems. At the industrial level..... a kiln with high velocit=
y
nozzle mixed burners can fire most any shape and configuration of an
enclosure evenly with stacking having little impact . (Unfortunately
.... potters don't typically use those burners. Expensive and high tech.)=
=
A potter's gas kiln with venturi type burners will be a little more "fuss=
y"
about its stacking..... and the amount of "fussyness" will relate directl=
y
to the quality of the castings of the venturi tubes and the operation
pressure of the burner (which relates to primary air entrainment
potential).
A wood kiln on the other hand typically depends on the draft induced by t=
he
exiting hot gasses to entrain all the primary and secondary air for
combustion...... and can be far more sensitive to stacking variations. I=
f
the kiln's fireboxes, flues, and chimney are well designed....... this
sensitivity is minimized. But such kilns are more sensitive to this fact=
or
than a well designed gas kiln would be. But you shouldn't have to leave
great vast open spaces in a wood kiln just to get it to fire to temperatu=
re
.
A LOT of craft potters gas kilns, oil kilns, and wood kilns I have seen i=
n
the past 30+ years are not all that well designed .............or sometim=
es
if they are well designed to start with,..... are not in good operational=
condition. So a lot of firing practices one sees out in the field revolv=
e
around dealing with specific kiln operational deficiency issues. As a
GROSS generalization .... and we know that there are exceptions to every
generalization....... the "junkier" the overall design and/or constructio=
n
of the kiln and its combustion system..... the "fussier" it will be to
stacking variations, operator skill, and atmospheric conditions.
I used to stack my noborigama very, VERY tight back in the early 80's. I=
t
fired fine. Pots looked good. Good color, good ash, pretty even firing.=
=
It was designed to induce LOTS of air if I needed it. At that time... as=
I
was stacking...... I was thinking of all the wood firing work that went
into firing each pot.... and how that was impacting how much I earned per=
hour. Space was very precious....... fill it! Over time... I have foun=
d
that I stacked looser and looser. And the look of the pots went from goo=
d
to better to even better. So I just raised my prices for my wood fired
work to compensate for the slightly less pots in a firing from leaving a
little more space.
best,
........................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086-5812 USA
JBaymore@compuserve.com
http://www.JohnBaymore.com
603-654-2752 (studio)
800-900-1110 (studio)
Lori Leary on sat 13 sep 03
Hi Janet,
You are right...mileage will vary. Everyone's idea of loose or tight will=
be
different, and of course the type of kiln will make a difference.
Generalizations are fine with me.
I'm glad you brought up the issue of early reduction to achieve consisten=
t
copper reds...I always did a "body reduction" at about ^ 011 to ^010 to h=
elp
with the reds, but what I found really seemed to help was burner assisted
cooling. I had a little updraft I made from an electric kiln shell lined
with fiber, I could look in and see the reds actually forming . Amazing =
to
see.
The temp problems are with the wood kiln...I suspect packing may be part =
of
the problem and maybe not working through the stall. I know very little
about wood kilns, but I sure am learning....
Best,
Lori
-----=20
From: "Janet Kaiser"
Please could everyone entering this debate state clearly what
exactly they mean by "loose" and what kiln type / size / fuel
they are using at what temperature range? The comparisons are not
going to be much help to anyone otherwise. Especially when taken
out of context later (as single stand-alone mail in the
archives).
Indeed, I think it is debatable what help Lori will specifically
glean from what anyone says, because all kilns are so different
plus all the other variables like timing, the ware being fired,
the glaze and all. BTW Lori, can you tell why the kiln is not
reaching temperature? Are there time restrictions at play beside
what you have already said?
And what about the temperature reduction is started at? I was
coincidentally talking to John Ambrose who makes the most
gorgeous ox blood / sang beouf high-fired stoneware pots and
platters yesterday and he said his "secret" (a guaranteed method
learned from a Swedish potter years ago) was to start reduction
at 840-850 =B0C. His firings last approx. eight hours to top
temperature and he said that this was critical for his glazes to
succeed.
Lori Leary on mon 15 sep 03
Just wanted to say thanks for all the on and off-list responses to my
question. While I don't have as much evidence supporting my particular
viewpoint as I would like, I have lots of input (pro and con) for
discussion with my teacher this week.
Most important, I think, is to find what works best for one's situation
while keeping an open mind to new practices and ideas. That, I suspect,
helps keep us and our work fresh.
Thanks again,
Lori L.
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