Kristin on mon 30 dec 02
Bill Schran just logged in on the holding/soaking
issue, and his post mentioned cones bending to their
"proper position." Ya'll may have noticed in my
accidental post to the list (intended to go to only
Chris, oops) that I am somewhat confused by the proper
position of regular cones vs. self-supporting cones.
I use the latter, so as to remove another variable in
the process (the
just-how-do-you-stick-the-cones-in-the-cone-pack
variable). But am not sure what my cones should look
like when at their perfect position.
A link here to an image I found on the Orton Web site:
http://www.ortonceramic.com/Firing/media/figure_6.gif
Unfortunately the page doesn't exactly spell out "the
middle cone is at its correct position."
I think that tip touching is right for regular cones,
but the above image, middle cone, is correct for
self-supporting. If the third cone (I use 5, 6, 7 when
shooting for ^6)) starts to bend, it's gotten too hot.
Am I right? Wrong? Sort of?
Thanks everyone - Kristin (The girl who gave out
little clay tokens/ornaments as presents this year --
to admit the holder to my housewarming/kiln-opening
party, at which the guests will finally receive their
Christmas presents. Sure hoping to follow through on
this promise sometime before spring!)
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John Rodgers on mon 30 dec 02
Kristin, in my own experience with free standing witness cones, I fire
them exactly like thebottom image you referred to. Middle cone
horizontal. In the real world of firing, You fire until your glaze is
like you want it. The indicator that the glaze is like you want it is
where the middle cone bends to. For example, when I fire Floating Blue,
I fire a cold cone 5, ie, I shut down my kiln just before the cone goes
fully horizontal. For other glazes that I use, I fire it to the point
the center cone tip touches. It just depends. For me in my kiln, when I
fire Floating Blue to cone 5 tip down, the glaze runs down my pots in a
way that I don't want, ie, to hot and overmatured. Just slightly above
horizontal and it turns out jjust right.
When I make up conepaks - 3 cones in a row - using the standard long
cones, not the free standing types, I use the angle on the bottom of the
cone to set the proper angle for the setting in the clay for the
conepaks. Then the process of firing is the same - Angle at which the
center cone goes down becomes a function of what you want out of the glaze.
Traditionally it means the particular glaze is matured, but there is
enough variance in glazes and their recipes that a lot of testing is
required so that you know what each glaze requires in the way of firing
time and heatwork to reach maturity. Your glaze may in reality be a cone
4-3/4 glaze. Then what? or a 5-1/2, then what? So test, test, test. Know
what your glaze requires, so that your interpretation of what the cone
angle says is correct. --- A few more minutes for this glaze, or shut it
off now!!!!
Regards,
John Rodgers
Birmingham, AL
Kristin wrote:
>Bill Schran just logged in on the holding/soaking
>issue, and his post mentioned cones bending to their
>"proper position." Ya'll may have noticed in my
>accidental post to the list (intended to go to only
>Chris, oops) that I am somewhat confused by the proper
>position of regular cones vs. self-supporting cones.
>
>I use the latter, so as to remove another variable in
>the process (the
>just-how-do-you-stick-the-cones-in-the-cone-pack
>variable). But am not sure what my cones should look
>like when at their perfect position.
>
>A link here to an image I found on the Orton Web site:
>http://www.ortonceramic.com/Firing/media/figure_6.gif
>Unfortunately the page doesn't exactly spell out "the
>middle cone is at its correct position."
>
>I think that tip touching is right for regular cones,
>but the above image, middle cone, is correct for
>self-supporting. If the third cone (I use 5, 6, 7 when
>shooting for ^6)) starts to bend, it's gotten too hot.
>
>Am I right? Wrong? Sort of?
>
>Thanks everyone - Kristin (The girl who gave out
>little clay tokens/ornaments as presents this year --
>to admit the holder to my housewarming/kiln-opening
>party, at which the guests will finally receive their
>Christmas presents. Sure hoping to follow through on
>this promise sometime before spring!)
>
>
>
>__________________________________________________
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>Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
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>
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>
>
>
william schran on mon 30 dec 02
Kristin asked about the correct position of cones when bent to
indicate having reached correct temperature. The link that was
provided showed self-supporting cones with the "firing" cone bent to
the 3 o'clock position. I have understood this to be the correct
position for all large cones. I let mine bend a bit further as I set
my cones in a clay pat at a slightly more severe angle than what
Orton recommends.
Bill
Chris Schafale on mon 30 dec 02
Hi Kristin,
I know what you mean. Orton says that "When the cone tip
reaches a point level with the base, it is considered properly fired;
however, the difference between a cone touching the shelf and a
cone at the 4 o'clock position is small and rarely affects the fired
results." They also say, "The 6 o=92clock position (90=B0 angle) is
considered the endpoint of cone bending." See the picture of the
template at:
http://www.ortonceramic.com/Firing/pc_convert_angle.html
If the base of the cone were at the level of the shelf, then the tip of
the cone would be touching the shelf at maturity. However, with a
self-supporting cone, it's not all that clear where the base of the
cone is interpreted to be. The pictures (see figure 4 on the same
page) suggest that Orton's idea of maturity for a self-supporting
cone is, as you say, with the tip of the cone floating somewhere
above the shelf. In any case, it sounds like, once the tip has gotten
past the 3 o'clock position, it bends much more quickly, so there's
not that much temperature difference from there to maturity.
The question of whether your guide cone has started to bend or not
is, I think, a different issue. Cones are not equally spaced,
temperature wise. Look at a cone chart sometime and you'll see.
So, if you happened to choose a set of cones whose maturation
temperatures were closer, then your "guard" cone would be starting
to bend, even as your middle cone came to maturity. With other
temperature ranges, that would not be the case.
Chris
> Bill Schran just logged in on the holding/soaking
> issue, and his post mentioned cones bending to their
> "proper position." Ya'll may have noticed in my
> accidental post to the list (intended to go to only
> Chris, oops) that I am somewhat confused by the proper
> position of regular cones vs. self-supporting cones.
>
> I use the latter, so as to remove another variable in
> the process (the
> just-how-do-you-stick-the-cones-in-the-cone-pack
> variable). But am not sure what my cones should look
> like when at their perfect position.
>
> A link here to an image I found on the Orton Web site:
> http://www.ortonceramic.com/Firing/media/figure_6.gif
> Unfortunately the page doesn't exactly spell out "the
> middle cone is at its correct position."
>
> I think that tip touching is right for regular cones,
> but the above image, middle cone, is correct for
> self-supporting. If the third cone (I use 5, 6, 7 when
> shooting for ^6)) starts to bend, it's gotten too hot.
>
Light One Candle Pottery
Fuquay-Varina, North Carolina, USA
(south of Raleigh)
candle@intrex.net
http://www.lightonecandle.com
John Britt on mon 30 dec 02
Kristin,
The correct angle of a matured cone is when it is perfectly arched and
touches the shelf. Self-supporting cones are easy as there is no plaque
involved. So when cone 5 arches and touches the shelf it has completed
100 per cent of heat work for that cone.
If you have regular large cones then they should be placed in a plaque at
an 82 degree angle, and I think the height of the plaque should be a 1/2"
high. (I am sorry but I am not certain of the exact height of the plaque
as I don't have my notes here. But it is something like that.) So when the
cone perfectly arches and touches the shelf, not the plaque, it is
complete.
From what I can see, the middle cone in the picture is at 3:00 o'clock and
represents 80 % of the heat work for cone 5 so it is 4.8.
Hope that helps,
John Britt
John Hesselberth on mon 30 dec 02
>
I can't access Orton's site this evening or I would try to quote the
reference. You have to read it carefully--it's not particularly well
written or easy to find if I remember correctly; however they define
reaching a particular cone as "tip touching" -- not 3 o'clock. They
don't say it that way. I think they quote it in degrees from a reference
point. I'm certain of this for regular large cones--I doubt it would be
different for self supporting, but that I'm not certain of. If I can get
into their site later I'll try to find it.
Regards,
John
http://www.frogpondpottery.com
http://www.masteringglazes.com
Snail Scott on tue 31 dec 02
At 09:33 PM 12/30/02 -0500, you wrote:
>The correct angle of a matured cone is when it is perfectly arched and
>touches the shelf...
Just a reminder...that's the the 'correct angle' of a
cone for a particular level of heat-work as specified
by the manufacturer. The 'correct angle' of the cone
for YOUR work is whatever gives the result you're
after. No one's glazes and clays are the same as anyone
else's. If your glazes look and act better with a
partial bend, then that's your firing temperature.
Cones give us a lot of flexibility, we can choose the
heat-work that's best for our stuff. Knowing that a
tip-to-the-shelf bend equals a particular heat-work
level is really useful, especially when comparing
results with other people, but tip-to-the-shelf isn't
the only acceptable level or firing! Most glazes aren't
too finicky about 1/2-cone variations, but some are. If
your glaze is happiest at ^5-1/2 or so, then fire to
that level. Glazes don't mature in one-cone increments
like a ticking clock, so you shouldn't feel that 'tip-
down' is the only 'right' cone position and aim for
it blindly. Let your glazes tell you what's needed.
Just be consistent when you find that point. (And
watch the angle of the cone in the pack - it makes a
huge difference in the outcome.)
-Snail
Arnold Howard on thu 2 jan 03
If the tip of a self-supporting cone touches the shelf, it is very
slightly over-fired (by only several degrees of temperature).
At one time, Paragon kiln manuals included a photo of a
self-supporting cone "fired to maturity" with the tip touching the
shelf. Then someone at Orton told me that when the tip touched the
shelf, the cone was considered slightly over-fired. So I changed
the photo.
Paragon's manuals now show a self-supporting cone fired to maturity
with the tip roughly even with the top of the built-in cone base.
With best wishes,
Arnold Howard
Paragon Industries, Inc.
--- Kristin wrote:
> Bill Schran just logged in on the holding/soaking
> issue, and his post mentioned cones bending to their
> "proper position." Ya'll may have noticed in my
> accidental post to the list (intended to go to only
> Chris, oops) that I am somewhat confused by the proper
> position of regular cones vs. self-supporting cones.
>
> I use the latter, so as to remove another variable in
> the process (the
> just-how-do-you-stick-the-cones-in-the-cone-pack
> variable). But am not sure what my cones should look
> like when at their perfect position.
>
> A link here to an image I found on the Orton Web site:
> http://www.ortonceramic.com/Firing/media/figure_6.gif
> Unfortunately the page doesn't exactly spell out "the
> middle cone is at its correct position."
>
> I think that tip touching is right for regular cones,
> but the above image, middle cone, is correct for
> self-supporting. If the third cone (I use 5, 6, 7 when
> shooting for ^6)) starts to bend, it's gotten too hot.
>
> Am I right? Wrong? Sort of?
>
> Thanks everyone - Kristin
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