Merrie Boerner on wed 25 apr 01
Marianne,
That is very interesting.....what do your books say about cone 10 lar=
ge
Orton cones ? and cone 12 ? I have always relied on the bending of the c=
one
over the pyrometer reading........now I'm curious.
Merrie
Cindy Strnad on wed 25 apr 01
Marianne,
Your ware has reached ^6 when a real, full-sized (non-defective) #6 cone
says it has. The actual temperature will vary, but ^6 isn't a temperature=
=2E
It's a measure of heat work. You can easily reach ^6 by holding at ^5
temperature for around an hour.
The newer kiln computers are programmed to take speed of rise into
consideration if you've told them to go to ^6, but this doesn't hold true=
if
you've told them to go to 2232F and hold for 30 minutes. In that case, yo=
u
may make it to ^7, or you may not quite. Only a real live cone will tell =
you
for sure. That's why you need them, no matter how great your controller m=
ay
be.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Tom Buck on wed 25 apr 01
The real temp is when the Cone 6 pyrometric cone bends to 3 o'clock. and
even then thee will be variations, one firing to the next. see Tony
Hansen's Magic of Fire book.
bfn. peace. tom b.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
Peter T. Wang on wed 25 apr 01
Marianne Lombardo writes:
>Confusion! Different references have different temperatures for a ^6
>firing.
(As many of you know and have said), cones measure heat work, not
temperature, so ^6 is not just, say, 2266 F. The maturation temperature
depends on the speed of the firing. Just check out Orton's website for
their latest cone temp. equivalents for various firing rates; this will
be the most reliable source of information, and even so they are only a
guide!
Then the natural question goes, why use cones, and why measure heat work?
And the natural answer is, cones are themselves ceramic materials and thu=
s
are the most accurate representation of what happens to the pots in a
firing. Just like in an oven, recipes don't omit how long you're suppose=
d
to roast or bake food. You need to know how long you're cooking
something, as well as how hot you cook it.
-peter
Ababi on thu 26 apr 01
We, have the same confusion.
I was told that the real ^6 connected to the speed of firing in the last =
3
hours. When my kiln is full (sometimes I write FOOL) the firing slow, whe=
n
it is less full than it is faster. I have automatic control, we do not us=
e
cones (except in raku for some glazes) and except very old kilns, So what
should I do stand near the kiln in the last 3 hours?
I work with glazes for ^6 and fire them to 1220C.
Except ^6 crystalline to 1222C
Now I added some numbers to your mess...
Ababi Sharon
ababisha@shoval.ardom.co.il
http://members4.clubphoto.com/ababi306910/
----- Original Message -----
From: "Marianne Lombardo"
To:
Sent: Thursday, April 26, 2001 12:21 AM
Subject: Cone Temperatures References Vary
Confusion! Different references have different temperatures for a ^6
firing.
My Potter Supply Catalog says ^6 is 2266 F
Wheel-thrown Ceramics book by Don Davis says ^6 is 2232 F
Potter's Book of Clay and Glazes by Chappell says ^6 is 2245 F
Electric Kiln Ceramics book by Zakin says ^6 is 2232 F
All the above are based on the large Orton cones.
Does anyone know what a REAL ^6 temperature should be (F)?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
_________________________________________________________________________=
___
__
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.
Frederich, Tim on thu 26 apr 01
Marianne,
The correct temperature for the Orton Large cone 6 at a 108 degree heatin=
g
rate is 2228 F an is 2266 F at a 270 degree heating rate. Some of the oth=
er
temperatures you mentioned are for Self Supporting cones. There is usuall=
y a
slight difference between Large and Self Supporting cones. The heating ra=
te
is important to know in finding the end point of a cone. The faster the
heating rate, the higher the end point of the cone. This is where the
time/temperature relationship (called heatwork) becomes so important.
Best regards,
Tim Frederich
-----Original Message-----
From: Marianne Lombardo [mailto:mlombardo@NEXICOM.NET]
Sent: Wednesday, April 25, 2001 6:21 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Cone Temperatures References Vary
Confusion! Different references have different temperatures for a ^6
firing.
My Potter Supply Catalog says ^6 is 2266 F
Wheel-thrown Ceramics book by Don Davis says ^6 is 2232 F
Potter's Book of Clay and Glazes by Chappell says ^6 is 2245 F
Electric Kiln Ceramics book by Zakin says ^6 is 2232 F
All the above are based on the large Orton cones.
Does anyone know what a REAL ^6 temperature should be (F)?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
_________________________________________________________________________=
___
__
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.
Frederich, Tim on thu 26 apr 01
Tom,
The actual end point of a pyrometric cone is 90 degrees or 6 0'clock or w=
hen
the tip of the cone almost touches the shelf or cone plaque. At 3 o'clock
the cone is only about one half of the way down.
Best regards,
Tim Frederich
-----Original Message-----
From: Tom Buck [mailto:Tom.Buck@HWCN.ORG]
Sent: Wednesday, April 25, 2001 11:48 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Cone Temperatures References Vary
The real temp is when the Cone 6 pyrometric cone bends to 3 o'clock. and
even then thee will be variations, one firing to the next. see Tony
Hansen's Magic of Fire book.
bfn. peace. tom b.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
_________________________________________________________________________=
___
__
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.
Brookssburgess@AOL.COM on thu 26 apr 01
It is my understanding that cones represent heat work over time rather =
than
a specific temp. The orton charts give temps for both large and small con=
es
and for more than one rate of climb to reach a temp.
Snail Scott on thu 26 apr 01
At 06:21 PM 4/25/01 -0400, you wrote:
>Confusion! Different references have different temperatures for a ^6
firing...
>Does anyone know what a REAL ^6 temperature should be (F)?
>>Marianne Lombardo
No such thing!
Seriously, what cones measure is not
temperature, but 'heat work', which is
why most of those charts give only
rough equivalents, correlated to the
speed of the firing. If the kiln hits,
say, 2250 F, in 4 hours, it may still be
a lower cone than one fired to 2200 for
24 hours. Time gives the temperature more
chance to 'do its thing' to the clay. The
cone charts can only give an approximate
temperature, based on a presumed rate of
increase. That is why, even with a pyrometer,
cones will give you a more accurate result
in many cases. Cones, being made of clay
themselves, respond to heat work similarly
to the work being fired, and reflect the
actual effects of the firing.
A pyrometer is a lovely tool, and indispen-
sible for soaking and firing down, but it
provides different information than the
cones do.
It doesn't matter what the temperature or the
cone is. It only matters that your clay and
glazes are optimally matured. Whatever means
you use to predict that, (cones; pyrometer +
length of firing; cords of wood x rate of
stoking; speed of turning the knobs up + time
on 'high'; etc.), you need to find the one
that works and stick with it consistently.
The pyrometer will not give useful information,
for instance, unless the firing is proceeding
at the same rate as usual. Some people fire
successfully by time alone, but only because
the rate of heating is consistent from one
firing to the next.
If a fully tipped ^6 gives you the appropriate
result, who cares what the temperature is? If
an 8 hour firing with a fixed rate of turn-ups
to 2240 F gives you the appropriate result, who
cares what the cone is?
The essence of all this is, firing clay requires
temperature AND time (heat work). A pyrometer
only measures one of those things.
vince pitelka on thu 26 apr 01
> That is very interesting.....what do your books say about cone 10
large
> Orton cones ? and cone 12 ? I have always relied on the bending of the
cone
> over the pyrometer reading........now I'm curious.
Merrie -
The cone is always the accurate reference. The cone indication varies
depending on duration of firing, but the effect on the wares also varies =
in
the same way, so the cone is the sure indication of what is happening to =
the
wares. The pyrometer only tells us temperature. Clay and glazes respond=
to
temperature, atmosphere, and duration of firing, and the cones, being
ceramic materials, respond in the same way.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
| |
|
