steve graber on tue 18 apr 06
32 degree is freezing but it's not necessarily ice. it depends on the size of the freezer. the *horse power* behind the icebox. you can freeze ice cubes in a tiny freezer, or a big freezer. just a matter of time to wait.
~ same with a kiln, just the other end of the spectrum.
see ya
steve
"F. Parker" wrote:
I need advice if anyone can help. I am confused by the concept of heat
work as it relates to cone temperatures. Specifically, the apparent
relationship between temperature and time as it relates to achieve, say
cone 6.
As I understand it, cone 6 might be x degrees for y minutes, or it might
also be n degrees (where ndependable way -- other than trial-and-error with cone packs -- to predict
what the target temperature should be for different ramp/hold sequences
for ^6 glaze firings? I have been using the program from MC6G, but it
fires to 2185 F which, I thought was below the standard ^6 temperature of
appx 2230. Everything I'm doing is oxidation, if that helps.
Many thanks for the advice.
Fred Parker
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F. Parker on tue 18 apr 06
I need advice if anyone can help. I am confused by the concept of heat
work as it relates to cone temperatures. Specifically, the apparent
relationship between temperature and time as it relates to achieve, say
cone 6.
As I understand it, cone 6 might be x degrees for y minutes, or it might
also be n degrees (where ndependable way -- other than trial-and-error with cone packs -- to predict
what the target temperature should be for different ramp/hold sequences
for ^6 glaze firings? I have been using the program from MC6G, but it
fires to 2185 F which, I thought was below the standard ^6 temperature of
appx 2230. Everything I'm doing is oxidation, if that helps.
Many thanks for the advice.
Fred Parker
John Hesselberth on tue 18 apr 06
On Apr 18, 2006, at 11:58 AM, F. Parker wrote:
> As I understand it, cone 6 might be x degrees for y minutes, or it
> might
> also be n degrees (where n> dependable way -- other than trial-and-error with cone packs -- to
> predict
> what the target temperature should be for different ramp/hold
> sequences
> for ^6 glaze firings? I have been using the program from MC6G, but it
> fires to 2185 F which, I thought was below the standard ^6
> temperature of
> appx 2230. Everything I'm doing is oxidation, if that helps.
Hi Fred,
Several points. First thermocouples are not perfectly calibrated--
they all read a little differently--pariculary the cheap ones most of
us use. That is why I had to set mine at 2185 to get cone 6 down to
where I wanted it. In the book, we tried to make it clear that you
will have to adjust this temperature appropriately for your kiln and
thermocouple. Cones are the gold standard. You can approximate the
temperature at which your cone will fall if you use the rates of rise
that Orton has in their tables IF your thermocouples are well
calibrated--and they rarely are. So loosen up. Go with what the cones
are telling you and don't worry so much about what the thermocouples
are saying. Once you figure out what temperature you need to set your
controller at to have the cone fall when you want it to it will be
relatively reproducible, although it will slowly drift as your
thermocouple ages.
Regards,
John
Lynn Goodman Porcelain Pottery on tue 18 apr 06
I start checking witness cones early. If the kiln shuts off before the
cones drop, I restart the kiln. If the cones drop, I assume that the
firing is complete--and the cones have never been wrong for me. The
cones are what you should go by--not a number on the pyrometer. If the
kiln shuts off before the cones drop on a regular basis, you need to
tune your controller.
Lynn
On Apr 18, 2006, at 11:58 AM, F. Parker wrote:
> I need advice if anyone can help. I am confused by the concept of heat
> work as it relates to cone temperatures. Specifically, the apparent
> relationship between temperature and time as it relates to achieve, say
> cone 6.
>
> As I understand it, cone 6 might be x degrees for y minutes, or it
> might
> also be n degrees (where n> dependable way -- other than trial-and-error with cone packs -- to
> predict
> what the target temperature should be for different ramp/hold sequences
> for ^6 glaze firings? I have been using the program from MC6G, but it
> fires to 2185 F which, I thought was below the standard ^6 temperature
> of
> appx 2230. Everything I'm doing is oxidation, if that helps.
>
> Many thanks for the advice.
>
> Fred Parker
>
> _______________________________________________________________________
> _______
> 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.
>
>
Lynn Goodman
Fine Porcelain Pottery
548 Court St.
Brooklyn, NY 11231
718-858-6920
Cell 347-526-9805
www.lynngoodmanporcelain.com
earlk on tue 18 apr 06
On Tue, 2006-04-18 at 11:58 -0400, F. Parker wrote:
> I am confused by the concept of heat
> work as it relates to cone temperatures. Specifically, the apparent
> relationship between temperature and time as it relates to achieve, say
> cone 6.
Fred,
Have you checked out Orton's explanation at:
http://www.ortonceramic.com/resources/reference/effect_heat.shtml
My rudimentary math and physics would say
that heat-work could be calculated as the area
underneath the temperature vs time curve, or
the integral of T dt where T = Temperature and
dt = change in time.
However, when you read Orton's explanation it
becomes obvious that one needs to apply
bounday conditions on this. One of the questions
is "What should the lower boundary be?".
Orton would lead one to believe it might be 100C
below the rated cone temperature.
Another question is "Is the heat-work linear with
time when the temperature is held constant?".
I have no clue if that holds true or not and I don't
think Orton adequately expresses it.
Another interesting question is how do the
manufacturers of computer kiln controllers
compute heat-work. Probably considered
proprietary information.
If you figure out more than I have let me know.
Thanks...
earlk...
bothell, wa, usa
Michael Wendt on wed 19 apr 06
Heat work is related to the energy needed to
change a solid to a liquid. It differs from material
to material. Other factors come into play in
clay-glaze systems, though.
Many good answers have been given. I want to add:
Dead mass affects the rate of firing.
One way to get more repeatable firings in an electric
kiln is to weigh the load and make it the same each
time.
Configuration also affects the firing. Load the taller
items nearer the top and bottom to improve temperature
uniformity.
Last, always use cones, even with a computer control.
Cones will give you a heads up when the thermocouple
starts to drift. Be sure to include a guard cone one
higher than your goal to detect overfiring.
Adjust your computer controller once you know
the cone readings under these conditions.
Regards.
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Hank Murrow on wed 19 apr 06
On Apr 18, 2006, at 10:08 PM, steve graber wrote:
> 32 degree is freezing but it's not necessarily ice. it depends on the
> size of the freezer. the *horse power* behind the icebox. you can
> freeze ice cubes in a tiny freezer, or a big freezer. just a matter
> of time to wait.
>
> ~ same with a kiln, just the other end of the spectrum.
Dear Steve & Fred;
Something that ought to be considered about the size of the
freezer/furnace, is the relation between surface area and volume. A big
kiln has less surface(from which to lose heat) than a small kiln. This
is because surface increases by the square of the dimensions, while
volume increases by the cube of the dimensions. This is why elephants
with almost no hair can survive on leafy matter, while hummingbirds
must consume lots of sugary nectar despite being well-insulated by
feathers.
It always requires proportionally more 'horsepower' to get a smaller
kiln to temperature.
Cheers, Hank
www.murrow.biz/hank
Susan Coville on wed 19 apr 06
Hi Fred,
Here's a simple explanation which I use to explain to my students. It is not so much a matter of temperature as it is a matter of how much heat is absorbed by objects. This is why cones are used, for they act in the same manner as our pots do, absorb heat.
My professor, Victor Sinski, explained it as "the number of kilo calories of heat adsorbed denotes the cone 'temp'." Temperature is, of course, a factor, but my experience has been, in order to reach the actual temperature noted on those charts Orton prints out is a variable. I have had a very long firing which yielded the correct cone, never reaching the target temperature.
The important variable here is often the glaze results. Since the visual and physical result of a glaze is a function of glass forming, I have done a very fast cone 6 and compared it to a very slow cone 6 and the same glaze would turn out remarkably different. There would be variations in the clay body as well, but these effects are much more subtle and best observed in the cross-section of a pot.
Since you spoke of what I presume to be a computer programable kiln, I can offer no other insight, for I believe in the simple methad, often trusting color of the kiln glow to even the kiln sitter's reaction or lack thereof.
The only difference I know of in the oxidation vs. reduction part of this is when I am firing in reduction it takes a lot more gas or wood to reach the temperature I am seeking than the straightforward method of oxidation. This is probably why reduction glazes have far more richness and depth than oxidation, the longer time, the longer glaze melt/formation time.
There's my fraction of gray matter, I know there are fine minds in this bunch who will offer far more.
Susan Coville
"F. Parker" wrote:
I need advice if anyone can help. I am confused by the concept of heat
work as it relates to cone temperatures. Specifically, the apparent
relationship between temperature and time as it relates to achieve, say
cone 6.
As I understand it, cone 6 might be x degrees for y minutes, or it might
also be n degrees (where ndependable way -- other than trial-and-error with cone packs -- to predict
what the target temperature should be for different ramp/hold sequences
for ^6 glaze firings? I have been using the program from MC6G, but it
fires to 2185 F which, I thought was below the standard ^6 temperature of
appx 2230. Everything I'm doing is oxidation, if that helps.
Many thanks for the advice.
Fred Parker
______________________________________________________________________________
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/
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Arnold Howard on wed 19 apr 06
This is one of the reasons some people use the
Ramp-Hold mode instead of Cone-Fire. If the
temperature drifts, you can very easily change the
target temperature in Ramp-Hold by a few degrees.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
From: "John Hesselberth"
> Several points. First thermocouples are not
> perfectly calibrated--
> they all read a little differently--pariculary the
> cheap ones most of
> us use. That is why I had to set mine at 2185 to
> get cone 6 down to
> where I wanted it.
Arnold Howard on wed 19 apr 06
You can download charts showing the rates and target
temperatures programmed into Cone-Fire mode for
Orton's Sentry controller. That will be a good
starting point in programming to a cone in Ramp-Hold
mode. Then, as John Hesselberth suggests, adjust the
target temperature of the final segment to get an
exact cone bend.
Go to this link and select "Sentry 12-Key Controller
Instructions" from the list of Acrobat files. The
charts are on pages 26 - 27:
http://www.paragonweb.com/Instruction_Manuals.cfm
(Or go to www.paragonweb.com , select Support, and
then Instruction Manuals from the drop menu.)
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
----- Original Message -----
From: "F. Parker"
Is there any
> dependable way -- other than trial-and-error with
> cone packs -- to predict
> what the target temperature should be for different
> ramp/hold sequences
> for ^6 glaze firings?
Ron Roy on wed 19 apr 06
Hi Fred,
Just to add a bit to what John said - and which I think is right on - I
have to set my controller to 1082C to get cone 04 down with a soak of -
when all the charts say it should happen at 1040C in a 60C per hour firing.
It's because each K theremocouple reads differently - replace a
thermocouple and you will need to find out what the new one will say -
using cones of course.
I find out how to program ramps by making adjustments to a program during a
firing and learning what to do to get what I want. Every kiln will be
different and every thermocouple will tell a different story - at least
that way of thinking will give the best chances of getting it right.
RR
>I need advice if anyone can help. I am confused by the concept of heat
>work as it relates to cone temperatures. Specifically, the apparent
>relationship between temperature and time as it relates to achieve, say
>cone 6.
>
>As I understand it, cone 6 might be x degrees for y minutes, or it might
>also be n degrees (where n>dependable way -- other than trial-and-error with cone packs -- to predict
>what the target temperature should be for different ramp/hold sequences
>for ^6 glaze firings? I have been using the program from MC6G, but it
>fires to 2185 F which, I thought was below the standard ^6 temperature of
>appx 2230. Everything I'm doing is oxidation, if that helps.
>
>Many thanks for the advice.
>
>Fred Parker
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Hank Murrow on wed 19 apr 06
On Apr 19, 2006, at 12:06 AM, Susan Coville wrote:
>
> The only difference I know of in the oxidation vs. reduction part of
> this is when I am firing in reduction it takes a lot more gas or wood
> to reach the temperature I am seeking than the straightforward method
> of oxidation. This is probably why reduction glazes have far more
> richness and depth than oxidation, the longer time, the longer glaze
> melt/formation time.
And do not forget that iron and other oxides convert to fluxes under
reducing conditions. I brought some interesting porcelain samples to
NCECA in Portland to show this effect.
Cheers, Hank
www.murrow.biz/hank
Eleanora Eden on thu 4 may 06
Hi Fred and all,
I know this was afew weeks ago but reading all the responses nobody mentioned
the importance of keeping detailed firing logs.
My thermocouples wander around quite a bit but I use lots of cone packs...both
at peeps and internally so I have a good record of what actually happened.
I refer to previous several firing logs as I fire so I have some ball park to look at.
Even so every time it is the cone packs that are the constant, not the thermocouples.
(I draw all the packs after the firing to complete the log.)
That is my 1.99c worth.
Eleanora
>I need advice if anyone can help. I am confused by the concept of heat
>work as it relates to cone temperatures. Specifically, the apparent
>relationship between temperature and time as it relates to achieve, say
>cone 6.
>
>As I understand it, cone 6 might be x degrees for y minutes, or it might
>also be n degrees (where n>dependable way -- other than trial-and-error with cone packs -- to predict
>what the target temperature should be for different ramp/hold sequences
>for ^6 glaze firings? I have been using the program from MC6G, but it
>fires to 2185 F which, I thought was below the standard ^6 temperature of
>appx 2230. Everything I'm doing is oxidation, if that helps.
>
>Many thanks for the advice.
>
>Fred Parker
>
>______________________________________________________________________________
>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.
--
Bellows Falls Vermont
www.eleanoraeden.com
F. Parker on fri 5 may 06
Thanks, Eleanora. I'm new at this, but one thing I have learned is how
important cone packs are. I included three in my last glaze firing,
placed on each level of the kiln -- bottom, middle and top. The kiln had
a controller and an Envirovent attached and running throughout the firing
and cooling.
I fully expected the top to be hottest and the bottom coolest. Oddly, the
results were just opposite. I have no idea why, but the cones definitely
indicated this outcome
Fred Parker
On Thu, 4 May 2006 21:57:16 -0400, Eleanora Eden
wrote:
>Hi Fred and all,
>
>I know this was afew weeks ago but reading all the responses nobody
mentioned
>the importance of keeping detailed firing logs.
>
>My thermocouples wander around quite a bit but I use lots of cone
packs...both
>at peeps and internally so I have a good record of what actually happened.
>
>I refer to previous several firing logs as I fire so I have some ball
park to look at.
>Even so every time it is the cone packs that are the constant, not the
thermocouples.
>(I draw all the packs after the firing to complete the log.)
Ivor and Olive Lewis on fri 5 may 06
Dear Eleanora Eden,
Kiln Logs, a necessary document.
I was looking at the specifications of a Data Logger which can record =
temperature almost continuously. It is able to record 6000 events and =
these can be downloaded to PC or laptop. Consider a ten hour firing and =
a cooling period of twice that then there would be a reading every three =
seconds (If my calcs are Ok!).=20
But the specs say that the readings are plus/minus 3% of the indicated =
value. So above 1000 deg C there is a potential error of sixty degrees =
or more.
I wonder how this compares with data output from electronic controllers =
supplied with commercial kilns ?
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Steve Slatin on fri 5 may 06
Ivor --
10 hrs firing plus 20 hrs cooling - 30 hrs total.
30 hrs * 60 minutes per hour - 1800 minutes.
6000 events spread evenly over 1800 minutes is
3 1/3 events per minute, one every 18 seconds.
You must have been thinking # of events per
minute instead of # of seconds between events.
Still, that's a heck of a lot of samples, and you
could draw a nice smooth temperature curve with
far fewer #'s.
-- Steve S
--- Ivor and Olive Lewis
wrote:
> Dear Eleanora Eden,
>
> Kiln Logs, a necessary document.
>
> I was looking at the specifications of a Data
> Logger which can record temperature almost
> continuously. It is able to record 6000 events
> and these can be downloaded to PC or laptop.
> Consider a ten hour firing and a cooling period
> of twice that then there would be a reading
> every three seconds (If my calcs are Ok!).
>
> But the specs say that the readings are
> plus/minus 3% of the indicated value. So above
> 1000 deg C there is a potential error of sixty
> degrees or more.
>
> I wonder how this compares with data output
> from electronic controllers supplied with
> commercial kilns ?
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Arnold Howard on fri 5 may 06
----- Original Message -----
From: "F. Parker"
> I fully expected the top to be hottest and the
> bottom coolest. Oddly, the
> results were just opposite. I have no idea why,
> but the cones definitely
> indicated this outcome
It would be interesting to experiment with the
thermal mass inside your kiln. Next time, load
heavier ware in the bottom of the firing chamber to
see how that affects the witness cones.
Using cone packs on three different shelves is an
excellent way to learn about heat distribution. It is
definitely worth the price of the cones.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Ivor and Olive Lewis on sat 6 may 06
Dear Steve Slatin,
Thanks for correcting my calcs. Yes. I imagine the plot would reflect =
the way the controller (me !) behaves. I will try to look at one of =
these things and get to know a bit more about it the next time I go to =
Adelaide.=20
Our Son, David, donated a lap top to which I can could connect it.=20
Best regards,
Ivor.
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