Jonathan Kaplan on tue 3 feb 98
To add to this discussion.
Orton cones measure time and temperature. End points of cones from
available cone charts provide the end points of the cone only, without
taking into consideration the load in the kiln...ware and furniture. And
this is very important for those on the list that use computer controllers.
Those with controllers need to set the firing temperature lower than the
chart or the built in cone table and also build in a hold at the end of the
program. I've covered this before in some rather lengthy posts, but you
need to take into consideration the load of the kiln, (the ware and the
refractories...posts, protps, shelves, setters, etc.) and the ambient
temperature of the kiln. Determine your rate of climb, end point, and soak,
write them down and adjust as necessary.
For instance, a full cone 06 electric bisque in one of our Paragon TnF
28-3 with the new DTC controllers has an end point of 1800degrees with a
30 minute hold. Cone 06 is down top and bottom. One of our other kilns uses
an end point of 1710 with a 30 minute hold. Our 2 others also differ.
The end point according to Orton is 1830 degrees for their large cones
fired at 270 degrees per hour.
Its important for accurate firings regardless of the ware and temperature
to know that the end points of each our your kilns will vary from not only
each other but also from the cone reference tables that are programmed into
most controllers as well as the Orton charts. Remember that these numbers
are temperature driven only and do not take into consideration the other
important factor in firing any kiln which is time.
Jonathan
Jonathan Kaplan, president jonathan@csn.net
http://www.sni.net/ceramicdesign/
Ceramic Design Group Ltd./Production Services
PO Box 775112
Steamboat Springs CO 80477
(USPS deliveries only)
Plant Location
1280 13th Street Unit 13
Steamboat Springs CO 80487
( UPS, courier, and common carrier deliveries)
(970) 879-9139*voice and fax
http://www.sni.net/ceramicdesign/
http://digitalfire.com/education/clay/kaplan1.htm
Kathi LeSueur on tue 3 feb 98
In a message dated 2/3/98 7:51:35 AM, you wrote:
<28-3 with the new DTC controllers has an end point of 1800degrees with a
30 minute hold. Cone 06 is down top and bottom. One of our other kilns uses
an end point of 1710 with a 30 minute hold. Our 2 others also differ.
The end point according to Orton is 1830 degrees for their large cones
fired at 270 degrees per hour.
>>
Jonathan,
I'd be interested at what rate of climb you use in your kilns fired with a
controller. I use an Evenheat for bisque with a controller. I also fire to
cone 06 with a 30 minute soak but my rate of climb is much slower than 270
degrees per hour. Usually about 185. This seems to work well for me.
Kathi LeSueur
Jonathan Kaplan on wed 4 feb 98
>----------------------------Original message----------------------------
>
>In a message dated 2/3/98 7:51:35 AM, you wrote:
>
><>28-3 with the new DTC controllers has an end point of 1800degrees with a
>30 minute hold. Cone 06 is down top and bottom. One of our other kilns uses
>an end point of 1710 with a 30 minute hold. Our 2 others also differ.
>
>The end point according to Orton is 1830 degrees for their large cones
>fired at 270 degrees per hour.
>>>
>
>Jonathan,
>I'd be interested at what rate of climb you use in your kilns fired with a
>controller. I use an Evenheat for bisque with a controller. I also fire to
>cone 06 with a 30 minute soak but my rate of climb is much slower than 270
>degrees per hour. Usually about 185. This seems to work well for me.
>
>Kathi LeSueur
We fore our bisque kilns at 250 degress F per hour, and all our electric
glaze kilns fire at 300 degress F/hour.
Jonathan
Jonathan Kaplan, president jonathan@csn.net
http://www.sni.net/ceramicdesign/
Ceramic Design Group Ltd./Production Services
PO Box 775112
Steamboat Springs CO 80477
(USPS deliveries only)
Plant Location
1280 13th Street Unit 13
Steamboat Springs CO 80487
( UPS, courier, and common carrier deliveries)
(970) 879-9139*voice and fax
http://www.sni.net/ceramicdesign/
http://digitalfire.com/education/clay/kaplan1.htm
David Woodin on wed 4 feb 98
A rate of climb of about 185 deg F will come out to be very close to 1838 deg
F for regular cones, or 1820 for iron free cones. Cones are accurate at the
published rate of climb on the cone table to find out what the temperature
would be for a different rate of climb make a graph cone 06 for example is
1823 @ 108 and 1852 @ 270 for regular cones. Plot temp on the vertical axis
and rate of climb on the horizontal axis, draw a line between 1823 and 1852,
look at 185 on rate of climb axis and draw a line up till it intersects the
line between 1823 and 1852 and it will read 1838. Iron free cones are 1816
@108 deg F and 1825 @ 270 deg F and self standing have different
temperatures.for these points
Orion/Baker on thu 5 feb 98
Because we often fire large pieces very slowly (at rates like 75'F/hr,
100'F/hr, 150'F/hr) maturation temperatures listed on the standard Orton
cone chart aren't accurate at all for us.
So, I contacted Orton and they sent specific maturation temperature/rate
curves for every cone we use (and at no cover charge). These are
absolutely fascinating -- and I would think ceramics profs and instructors
might want to be familiar with what they are and how they work.
Orton's number, in Westerville, Ohio, is 614-895-2663. I think there's an
Orton website, too.
Ellen Baker - Glacier, WA
orion@telcomplus.net
Dana Henson on fri 6 feb 98
What is an end point and how does it relate to firing? Thanks.
Dana Henson
Stephen Mills on sun 8 feb 98
Dana,
The "end point" refers to when the tip of the cone bends right over and
touches the shelf.
Pyrometers display the temperature current in the Kiln at the moment you
look at them. Cones measure "accumulated heatwork". Being made out of
the same materials as the glazes we use, they behave in the same way and
consequently are by far the most accurate way of "reading" a Kiln. If
you fire very slowly you will achieve the right amount of heatwork to
melt your glazes at a much lower "indicated" temperature. If you fire
slowly and watch a pyrometer up to the "stated" glaze melting point you
are at risk of a serious overfire.
Sorry to sound so pedantic, it's the only way I can explain this.
Steve
Bath
UK
In message , Dana Henson writes
>----------------------------Original message----------------------------
>What is an end point and how does it relate to firing? Thanks.
>Dana Henson
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Richard Mahaffey on sat 8 jan 05
Mel,
Orton makes these holders for the large cones. I recall that they call
them plaques.
They hold the cones at the correct angle and are quite deep so the cone
bends more like a fish hook then a gentle curve.
If you use the plaques you find that the cones melt much closer to the
published temperatures.
Speaking of slow firings.
I like my firings to be long or to have a shallow slope toward the end,
I don't mind too much if the first part of the temperature rise is
quite steep. Not much happening with glaze melting below bisque
temperatures. At TCC (Tacoma Community College) we set our cones in
kiln putty. Not nearly as deep as the cone plaques set cones. I
would guess that our cone 10 firings are closer to cone 9 or 9.5.
Reduction seems to help even if the firing is a little below the
desired cone.
Reminds me of the time a fellow grad student came into the studio from
the kiln yard and said that "I have the kiln in oxidation at cone 6 to
even out the temperature difference between the top and the bottom of
the kiln".
F Carlton Ball seemed to grow to 7 feet tall and he yelled "To hell
with the cones REDUCE"
The grad firing the kiln ran out and put the kiln into reduction right
away. When the grad came back in Carlton said "If you reduce well a
kiln can be fired a cone lower and still have fine looking glazes".
Carlton postulated that "reducing a gas kiln slows the firing and the
fact that iron acts like a flux in reduction works in your favor".
He reminded us that "in oxidation iron is/can be quite refractory
making glazes appear dry and under-fired. Oxidation atmosphere tends
to allow a kiln to fire much faster, thus lowering the heat work for a
given temperature."
My experience seems to bear this out. The best firings we had were in
a old hard brick downdraft kiln that took 24 hours to fire-15 hours
above cone 08 in reduction. Great celadons, truly beautiful glazes
that just sung to you with a clean color. Cooling was equally slow.
I wonder how long it took the Song Dynasty potters to fire a kiln of
celadon glaze pots.
We started firing over night a school. Start the kiln at 5 or 6 pm.
Into reduction at 7:30 - 8:00 am oxy probe reading of .07+ off at 6
pm. Beautiful Celadon glazes when on good porcelain. Outrageous
color on Southern Ice, worth the money! The matt glazes are great
too, as are the iron saturates and Kaki glazes. Shino is good too.
We do not turn the gas up very much and want a nice slow rise with the
rise slowest above cone 8.
YMMV
Rick in Tacoma where the promised snow did not arrive. So I guess it
is back to class on Monday ;-(
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