Carole Fox on mon 19 sep 05
A friend of mine just got her first kiln(a small Cress) given to her. I went
over to help her out on it's maiden voyage and was surprised to find the
kiln had no elements in the center. How would one load a kiln like that? I
did the best I could and it fired fine for bisque. But, I'm worried about
the glaze firing.
Carole Fox
Silver Fox Pottery
Elkton, MD
silverfoxpottery@comcast.net
mtigges@NOSPAM_SHAW.CA on mon 19 sep 05
On Mon, Sep 19, 2005 at 01:09:44PM -0400, Carole Fox wrote:
> A friend of mine just got her first kiln(a small Cress) given to her. I went
> over to help her out on it's maiden voyage and was surprised to find the
> kiln had no elements in the center. How would one load a kiln like that? I
> did the best I could and it fired fine for bisque. But, I'm worried about
> the glaze firing.
Is it a removeable section? If so, then remove it for glaze firings.
I fire to cone 6, and my kiln can't get past cone 1 with the blank
ring in it. It's certainly handy to do one bisque firing per two
glaze firings though.
Mark.
Carole Fox on mon 19 sep 05
Mark-
It seems like a one piece kiln- at least the jacket is. There are two peeps,
one each at top and bottom. The configuration seems really limiting, or does
the middle get heated from the bottom and insulated from the top?
Thanks.
Carole Fox
Silver Fox Pottery
Elkton, MD
silverfoxpottery@comcast.net
> Is it a removeable section? If so, then remove it for glaze firings.
> I fire to cone 6, and my kiln can't get past cone 1 with the blank
> ring in it. It's certainly handy to do one bisque firing per two
> glaze firings though.
>
> Mark.
Arnold Howard on mon 19 sep 05
From: "Carole Fox"
>A friend of mine just got her first kiln(a small Cress) given to her. I
>went
> over to help her out on it's maiden voyage and was surprised to find the
> kiln had no elements in the center. How would one load a kiln like that? I
> did the best I could and it fired fine for bisque. But, I'm worried about
> the glaze firing.
I am assuming that the kiln has no element grooves in the center section.
Since the kiln is small, it will probably fire evenly without a center
element.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Snail Scott on tue 20 sep 05
At 01:09 PM 9/19/2005 -0400, you wrote:
>...surprised to find the
>kiln had no elements in the center...
This balances out OK.
There are no elements in lids, either,
or in most floors, and we don't worry
much about that. The air in the kiln will
get evenly hot, and the slight difference
in direct radiant heat (which sometimes
causes 'shadow') is seldom discernable and
won't be made any worse for having fewer
elements. If it hits temperature, it will
do so evenly along as the elements are
placed evenly. Even spacing is the part we
care about, not the number. Number of
elements (amount of power) sets the maximum
temperature for a kiln of a given volume,
but has only a slight effect on evenness.
If you are worried about a center shelf that
is blocked from direct element access, just
soak a little while at peak temperature, to
give the heat a chance to radiate evenly
throughout the kiln. It'll get there.
I used to actually turn down the center
elements on my kiln, since they weren't
needed to hit lower temperatures. The top
and bottom rings were sufficient to reach
the cone I needed, and it was perfectly
even.
-Snail
Arnold Howard on tue 20 sep 05
From: "Carole Fox"
> It seems like a one piece kiln- at least the jacket is. There are two
> peeps,
> one each at top and bottom. The configuration seems really limiting, or
> does
> the middle get heated from the bottom and insulated from the top?
The center section of an electric kiln requires a lot less heat than the top
and bottom sections. This is because the brick lid and bottom absorb so much
energy. They are large thermal masses.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
louroess2210 on fri 11 nov 05
I recently read a post which suggested that the bottom layer of a
kiln have at least four inch posts. Is this the consensus of the
group? Would this help with heat distribution? Are there any other
guidelines for loading as to where to put different size pieces. I
have used cones in my firings and the firing seems to be very even
top to bottom.
Thanks
Lou
steve graber on fri 11 nov 05
for me my kiln is coldest at the bottom (parabola-downdraft-gas). maybe i should have done a thicker layer of insulation here, it likely heat sinks into the foundation. i did add a trough design at the bottom but for me it doesn't work well in drawing down the flames under the floor zone.
what i do is use this space for thin work, use glazes that work ok at cone 8/9, or place unglazed work here & use the claybody color.
i post with the little 4 incher's & stack away!
see ya
steve
louroess2210 wrote:
I recently read a post which suggested that the bottom layer of a
kiln have at least four inch posts. Is this the consensus of the
group? Would this help with heat distribution? Are there any other
guidelines for loading as to where to put different size pieces. I
have used cones in my firings and the firing seems to be very even
top to bottom.
Thanks
Lou
______________________________________________________________________________
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Earl Brunner on fri 11 nov 05
Electric of fuel fired? Makes a difference.
louroess2210 wrote:I recently read a post which suggested that the bottom layer of a
kiln have at least four inch posts. Is this the consensus of the
group? Would this help with heat distribution? Are there any other
guidelines for loading as to where to put different size pieces. I
have used cones in my firings and the firing seems to be very even
top to bottom.
Thanks
Lou
______________________________________________________________________________
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
e-mail: brunv53@yahoo.com
Taylor from Rockport on fri 11 nov 05
Hey Lou:
You didn't say what type of kiln you use or how big it is. A quick search
of your posts didn't help me.
I fire an old but fantastic paragon A99B, ~7 cu ft electric kiln. Max
heatwork is cone 8, and I fire to cone 6. I have placed two half shelves on
four kiln posts placed on their sides directly on the bottom of the kiln.
That gives about an inch from the kiln floor to the bottom of my first
shelf. I have had no problems with unevenness in my kiln.
I could see larger gaps under the first shelf especially for fuel burning
kilns what wants some of that heat to go under that first shelf, and for
other such kilns what have down draft breath. I'm sure others are going to
be pitching in here.
Taylor, in Rockport TX, where his second pit firing isn't going as well as
his first, ping, ping, ping. It's cooking away now, no flames. Open
tomorrow afternoon. Sorry Louis, no seawater soaked steel wool this time.
Maybe Sunday!
On Fri, 11 Nov 2005 07:27:43 -0700, louroess2210
wrote:
>I recently read a post which suggested that the bottom layer of a
>kiln have at least four inch posts. Is this the consensus of the
>group? Would this help with heat distribution? Are there any other
>guidelines for loading as to where to put different size pieces. I
>have used cones in my firings and the firing seems to be very even
>top to bottom.
>Thanks
>Lou
>
>______________________________________________________________________________
>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.
claybair on fri 11 nov 05
Lou,
You're doing something right, with the right kiln, right conditions etc.
Who cares what the consensus is....don't change a thing!
Gayle Bair - if it ain't broke ... don't fix it!
Bainbridge Island, WA
Tucson, AZ
http://claybair.com
-----Original Message-----
From: Clayartlouroess2210
I recently read a post which suggested that the bottom layer of a
kiln have at least four inch posts. Is this the consensus of the
group? Would this help with heat distribution? Are there any other
guidelines for loading as to where to put different size pieces. I
have used cones in my firings and the firing seems to be very even
top to bottom.
Thanks
Lou
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.362 / Virus Database: 267.13.0/167 - Release Date: 11/11/2005
mtigges@NOSPAM.SHAW.CA on fri 11 nov 05
On Fri, Nov 11, 2005 at 07:27:43AM -0700, louroess2210 wrote:
> I recently read a post which suggested that the bottom layer of a
> kiln have at least four inch posts. Is this the consensus of the
> group? Would this help with heat distribution? Are there any other
> guidelines for loading as to where to put different size pieces. I
> have used cones in my firings and the firing seems to be very even
> top to bottom.
> Thanks
> Lou
>
I have read conflicting advice. I've never read that one should place
very thin platters on the bottom of the kiln, though I have read
advocates of big pieces on the top, and big pieces on the bottom.
Regardless, the motivation is always even firing. I say, if your
firings are even, keep doing what you're doing.
For me, my kiln is always cooler on the bottom by about half a cone.
I don't care about it for bisque. But for glaze it matters. I find
that tall pieces on the bottom on one half, and then a half shelf on
the other half for rectangular dishes works very well to even out the
heat work. Of course, above that I have a full shelf for more work
near the top of the kiln.
Regards,
Mark.
Ron Roy on mon 14 nov 05
I think this comes from trying to get an electric kiln (no element on the
bottom) to heat up properly on the bottom.
If the bottom shelf is too low it cuts off radiation from the bottom elements.
RR
>I recently read a post which suggested that the bottom layer of a
>kiln have at least four inch posts. Is this the consensus of the
>group? Would this help with heat distribution? Are there any other
>guidelines for loading as to where to put different size pieces. I
>have used cones in my firings and the firing seems to be very even
>top to bottom.
>Thanks
>Lou
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Debbie White on mon 14 nov 05
How high off the floor should the bottom shelf be if there is an element on
the bottom? My bottom tend to be the hottest....so I don't put the that
element on high...as it will overfire.
Appreciate your advice.
Debbie White
Pontypool, Ontario
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Ron Roy
Sent: November 14, 2005 1:45 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Kiln loading question
I think this comes from trying to get an electric kiln (no element on the
bottom) to heat up properly on the bottom.
If the bottom shelf is too low it cuts off radiation from the bottom
elements.
RR
>I recently read a post which suggested that the bottom layer of a kiln
>have at least four inch posts. Is this the consensus of the group?
>Would this help with heat distribution? Are there any other guidelines
>for loading as to where to put different size pieces. I have used
>cones in my firings and the firing seems to be very even top to bottom.
>Thanks
>Lou
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
____________________________________________________________________________
__
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.
Arnold Howard on tue 15 nov 05
You should be able to fire ware that is placed directly on the kiln bottom.
Raise the shelf so that there are a couple of rows of elements between the
shelf and the kiln bottom.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
----- Original Message -----
From: "Debbie White"
> How high off the floor should the bottom shelf be if there is an element
> on
> the bottom? My bottom tend to be the hottest....so I don't put the that
> element on high...as it will overfire.
William & Susan Schran User on tue 15 nov 05
On 11/14/05 8:00 PM, "Debbie White" wrote:
> How high off the floor should the bottom shelf be if there is an element on
> the bottom? My bottom tend to be the hottest....so I don't put the that
> element on high...as it will overfire.
How high does the manufacturer recommend?
How high off the floor is your bottom shelf now?
Do you have a downdraft vent (venting from bottom)?
In my JX18 L&L, with downdraft vent, no bottom element, I have the bottom
shelf on 3" posts to achieve very even firings.
In my Olympic updraft gas kiln, flame enters through floor, I have 4" posts
to achieve even firings.
At school we had a 29" diameter kiln with floor element, got even firings
with 2" posts under bottom shelf, no vent system.
You'll need to try different heights until you find what works for you in
your situation.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
William & Susan Schran User on tue 15 nov 05
On 11/15/05 9:21 AM, "Arnold Howard" wrote:
> You should be able to fire ware that is placed directly on the kiln bottom.
> Raise the shelf so that there are a couple of rows of elements between the
> shelf and the kiln bottom.
Howard - I respect your opinions and technical knowledge, but firing pottery
on the floor of a kiln with an element in the bottom just seems totally
wrong. I also believe firing pottery on the kiln floor without a bottom
element is wrong also, but for other reasons.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
Ron Roy on tue 15 nov 05
Hi Deaf,
Best to use cones and find out what works best.
One way to hold back a hot spot is to stack more in that area - stuff like
plates - because you use more shelves will do that for instance. The more
shelves in an area the more heat is needed to reach temperature.
I would not recommend that in a bisque firing because the bottom cools
faster than the top and platters are more likely to bisque dunt - same for
bowls.
RR
>How high off the floor should the bottom shelf be if there is an element on
>the bottom? My bottom tend to be the hottest....so I don't put the that
>element on high...as it will overfire.
>
>Appreciate your advice.
>
>Debbie White
>Pontypool, Ontario
>
>-----Original Message-----
>From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Ron Roy
>Sent: November 14, 2005 1:45 PM
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Kiln loading question
>
>I think this comes from trying to get an electric kiln (no element on the
>bottom) to heat up properly on the bottom.
>
>If the bottom shelf is too low it cuts off radiation from the bottom
>elements.
>
>RR
>
>>I recently read a post which suggested that the bottom layer of a kiln
>>have at least four inch posts. Is this the consensus of the group?
>>Would this help with heat distribution? Are there any other guidelines
>>for loading as to where to put different size pieces. I have used
>>cones in my firings and the firing seems to be very even top to bottom.
>>Thanks
>>Lou
>
>Ron Roy
>RR#4
>15084 Little Lake Road
>Brighton, Ontario
>Canada
>K0K 1H0
>Phone: 613-475-9544
>Fax: 613-475-3513
>
>____________________________________________________________________________
>__
>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.
>
>______________________________________________________________________________
>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.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Mary White on wed 16 nov 05
Bill, will you tell us what your reason is for not firing pottery on
the kiln floor if there's no floor element? My kiln has just two
peepholes and the bottom one is only about 2" above the floor. If I
put a shelf up on stilts the peep looks directly at the side of the
shelf. So I fire on a shelf that's sitting directly on the floor. So
far no problems.
Mary White
Madeira Park, BC
Canada
>
>
>Howard - I respect your opinions and technical knowledge, but firing pottery
>on the floor of a kiln with an element in the bottom just seems totally
>wrong. I also believe firing pottery on the kiln floor without a bottom
>element is wrong also, but for other reasons.
>
>-- William "Bill" Schran
> Fredericksburg, Virginia
> wschran@cox.net
> wschran@nvcc.edu
>
>______________________________________________________________________________
>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.
--
Mary White
HARBOUR PUBLISHING
Box 219
Madeira Park, BC
V0N 2H0
------------------
For current news and complete book & author information, visit our
website, http://www.harbourpublishing.com.
William & Susan Schran User on wed 16 nov 05
On 11/16/05 5:32 PM, "Mary White" wrote:
> Bill, will you tell us what your reason is for not firing pottery on
> the kiln floor if there's no floor element? My kiln has just two
> peepholes and the bottom one is only about 2" above the floor. If I
> put a shelf up on stilts the peep looks directly at the side of the
> shelf. So I fire on a shelf that's sitting directly on the floor. So
> far no problems.
Well, my comment was about pottery on the kiln floor, not on a shelf on the
floor, but I'll address that also.
If one places pottery directly on the kiln's soft brick floor, any glaze
runs will eat right into the brick.
Pottery fired on a shelf that's laying on the kiln floor may be subject to
some uneven heating that might be an issue for large flat work.
If one is using a vent system that draws air out through the bottom of the
kiln, as many systems do, then the bottom shelf must be propped up off the
floor.
If the bottom spy hole is too low, you could always drill another a bit
higher.
Do you place witness cones on the bottom shelf? If so, are the cones bending
the same top & bottom?
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
Arnold Howard on thu 17 nov 05
Often it isn't feasible to load ware directly onto the firebrick bottom. As
Bill mentioned, there is a risk of damage from running glazes. And the
bottom isn't perfectly flat like a shelf. There is also less heat there
since the massive firebrick surface absorbs so much energy.
Nevertheless, Paragon has always taken the position that it is possible to
fire ware on a kiln-washed brick bottom. You may end up gaining more usable
interior space by doing that. It is a matter for experimentation since every
kiln is unique.
Laying a shelf directly onto the brick bottom makes that area of the kiln
even cooler, because the shelf acts as a heat sink. That is something to
consider when you are planning your load.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
From: "William & Susan Schran User"
> On 11/16/05 5:32 PM, "Mary White" wrote:
>
>> Bill, will you tell us what your reason is for not firing pottery on
>> the kiln floor if there's no floor element? My kiln has just two
>> peepholes and the bottom one is only about 2" above the floor. If I
>> put a shelf up on stilts the peep looks directly at the side of the
>> shelf. So I fire on a shelf that's sitting directly on the floor. So
>> far no problems.
>
> Well, my comment was about pottery on the kiln floor, not on a shelf on
> the
> floor, but I'll address that also.
> If one places pottery directly on the kiln's soft brick floor, any glaze
> runs will eat right into the brick.
Ivor and Olive Lewis on thu 25 may 06
Dear Gaye,
The question of Reduction in an electric kiln is an interesting one. I =
have mentioned it before but not given an elaborate explanation.
Commonly we are told, the atmosphere in an electric kiln will be =
oxidising or neutral. This belief seems to stem from two ideas. The =
first is that we are not introducing anything that will change into =
carbon monoxide which is always named as the reducing agent. The second =
is that air contains oxygen and there is nothing in the kiln that will =
consume this by burning.
However, what is never discussed is Carbon dioxide, how it enters the =
electric kiln atmosphere or what it can do when heated.
Many clays contain some form of organic material but this burns away =
when the products are fired. Glazes may contains mall amounts of =
adhesives which are organic. When these burn there will be a residual =
increase of carbon dioxide in the kiln atmosphere. But I have never seen =
it mentioned that other sources of Carbon dioxide are invariable =
introduced. Consider...Whiting or other carbonate compounds are =
introduced as glaze ingredients (This sort of thinking is common in =
science. Workers are so engaged in what they are seeking that they =
disregard the obvious, the commonplace). Alkali earth carbonates freely =
decompose when they are heated. (MgCO3 about 350 C, CaCO3 about 850 C =
and SrCO3 above 1300 C). Alkali metal carbonates react with free silica =
above their melting points.They do not decompose under the influence of =
heat at the temperatures we use. If they are in a glaze recipe then this =
becomes another source of Carbon dioxide in an electric kiln.
Some of this gas will diffuse from the glaze before it fuses. Some may =
be trapped in the glaze after it fuses. Some may only be generated after =
the glaze has matured. No one has thought to mention that in the text =
books glazing ! ! !.
The next step in difficult to understand. It is documented, but not =
mentioned even in the newer pottery text books. ( nor might it be found =
in college science books) But the experience of Mel Jacobson is good =
evidence to support what I am about to tell you. At atmospheric pressure =
Carbon dioxide can decompose. It dissociates to Carbon Monoxide and =
Oxygen at temperatures above the range 320-400 C. As pressure rises, as =
it might if the free gas were contained as bubbles in a glaze, it can =
even liberate elemental carbon.
This gives us a scenario where Diffusion into the glaze from the =
external atmosphere in the kiln is unnecessary to induce reduction =
within a glaze.=20
This may enable Mel to understand why he can get reduction effects after =
a firing with a strongly oxidising atmosphere.
What about burning slivers of stick during cooling, as Mel describes. =
Perhaps this gives an inert atmosphere or one that will mop up any =
oxygen that bubbles out of the glaze as Ferric oxide decomposes while a =
kiln is slowly cooling.
This is a complex topic and I am still, albeit slowly, thinking things =
through. But thanks to your question I have been able to put another =
small segment into place to get a rational and testable answer.
I would imagine that there is insufficient free carbon monoxide escaping =
into the kiln to affect the metal of our elements. If there were, it =
would , in the presence of Oxygen ignite and 'burn to carbon dioxide.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
nal Message -----=20
From: Sekula Pottery=20
To: iandol@WESTNET.COM.AU=20
Sent: Wednesday, 24 May 2006 10:46
Subject: Kiln Loading Question
Dear Ivor,
I was intrigued by Mel's recent post. I have posted the paragraph that =
I am referring to below. I have searched and searched the archives but =
am unable to find where you have discussed that loading an electric kiln =
in a certain way can result in semi-reduction. Would you explain how to =
do that and do this semi-reduction atmosphere hurt the coils?=20
Thank you so much.
Gaye Sekula
Converse, Texas
that is going on in their kiln? how many electric firing potters
understand that even electrics can go into semi-reduction
if the kiln is loaded a certain way. how many potters have
fired a totally oxidized kiln, and wanted that result, and try
to understand what happens.? how many potters with gas kilns
can repeat a firing accurately?
Jim Murphy on thu 25 may 06
On May 25, 2006, 3:25 AM, Ivor wrote:
> At atmospheric pressure Carbon dioxide can decompose. It dissociates to C=
arbon
> Monoxide and Oxygen at temperatures above the range 320-400 C.
> I would imagine that there is insufficient free carbon monoxide escaping =
into
> the kiln to affect the metal of our elements. If there were, it would , i=
n the
> presence of Oxygen ignite and 'burn to carbon dioxide.
Hi Ivor,
Additionally, industrial Hydrogen-producing techniques have found Hydrogen
may be made by passing CO and steam over hot (400=B0C) iron oxide or cobalt
oxide ... CO + H2O -> CO2 + H2
A claybody and/or glaze with iron oxide or cobalt oxide, in the kiln with
superheated steam and CO, may produce Hydrogen [a known reduction agent]
yielding reduction effects.
Best wishes,
Jim Murphy
Ivor and Olive Lewis on fri 26 may 06
Dear Jim Murphy,
Yes, I am aware of those processes. I believe the metals act as =
catalysts. Although interesting I do not believe that would be a useful =
process for the average potter. Getting a supply of Carbon Monoxide and =
superheated steam into a kiln might pose some problems, including safety =
hazards.
The second time I saw Hydrogen generated was by passing water vapour =
over red hot Iron filings.=20
Knew you would chip in with some gem of knowledge.
Best regards.
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