John Hesselberth on mon 30 dec 02
Hi Everyone
I finally got into the Orton site. One clue is the sentence:
> As the deformation reached the end point, going from 5 to 6 o'clock=20
> only 1=B0C was required to effect the change of one clock position=20
> deformation.
at
http://www.ortonceramic.com/Firing/pc_convert_angle.html
Figure 4 on the above page shows a set of cones that look to be between=20=
4 and 6 o'clock, but as they point out their is only 1 deg C difference=20=
5 and 6 o'clock Earlier on the page they say there is a 5 deg C=20
difference between 1 and 2 o'clock.
The slightly clearer statement is:
> When the cone tip reaches a point level with the base, it is =
considered=20
> properly fired; however, the difference between a cone touching the=20
> shelf and a cone at the 4 o'clock position is small and rarely affects=20=
> the fired results.
at
http://www.ortonceramic.com/Firing/pc_whyuse.html
They do not differentiate between self supporting and regular and, in=20
fact, the cones referenced in Figure 4 above are self supporting. So,=20
tip-touching (in my terminology) =3D reaching that cone.
Regards,
John
http://www.frogpondpottery.com
http://www.masteringglazes.com
Kristin on tue 31 dec 02
So, from everyone's responses, the cones at the bottom
of my little test tube page show that I hit a good ^6?
(Again, the cones shown are 5, 6, and 7)
http://www.tamarac.net/alby/test_tubes/
Hmmm. I had previously thought I'd overfired AND held
too long. Now it looks as though my 30-minute hold was
the sole culprit of my problems (my cooling rate was
about 100* C/hour, from 1200* C to opening).
I understand that it's all about being consistent, and
finding the right angle for my own particular glazes,
etc. But since I'm just trying this for the first
time, just getting the cone thing down is enough fun
for me.
(And it IS fun, yes it is. I only wish I could fire up
my kiln with new tests every day instead of every
other weekend, when I have an entire day free.)
--- John Hesselberth wrote:
> Hi Everyone
>
> I finally got into the Orton site. One clue is the
> sentence:
>
> > As the deformation reached the end point, going
> from 5 to 6 o'clock
> > only 1°C was required to effect the change of one
> clock position
> > deformation.
>
> at
>
>
http://www.ortonceramic.com/Firing/pc_convert_angle.html
>
> Figure 4 on the above page shows a set of cones that
> look to be between
> 4 and 6 o'clock, but as they point out their is only
> 1 deg C difference
> 5 and 6 o'clock Earlier on the page they say there
> is a 5 deg C
> difference between 1 and 2 o'clock.
>
> The slightly clearer statement is:
>
> > 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.
>
> at
>
> http://www.ortonceramic.com/Firing/pc_whyuse.html
>
> They do not differentiate between self supporting
> and regular and, in
> fact, the cones referenced in Figure 4 above are
> self supporting. So,
> tip-touching (in my terminology) = reaching that
> cone.
>
> Regards,
>
> John
>
> http://www.frogpondpottery.com
> http://www.masteringglazes.com
>
>
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Dave Finkelnburg on tue 31 dec 02
Kristin,
You are right. Of course you are also right, what does this cone
position mean to you and your glazes?
I also worry about what it means to my clay, and then try to adjust my
glazes to get the right effects on my clay at it's firing temperature. You
do want good, repeatable clay body vitrification -- not too glassy but not
porous, either. Porous leads to functional problems like leakage and glaze
crazing. Overfired clay is too brittle, and not durable.
Happy New Year!
Dave Finkelnburg, watching the snow sift down onto the bare branches
of the lilacs here in southern Idaho
----- Original Message -----
From: "Kristin"
So, from everyone's responses, the cones at the bottom
of my little test tube page show that I hit a good ^6?
(Again, the cones shown are 5, 6, and 7)
http://www.tamarac.net/alby/test_tubes/
Hmmm. I had previously thought I'd overfired AND held
too long. Now it looks as though my 30-minute hold was
the sole culprit of my problems (my cooling rate was
about 100* C/hour, from 1200* C to opening).
I understand that it's all about being consistent, and
finding the right angle for my own particular glazes,
etc. But since I'm just trying this for the first
time, just getting the cone thing down is enough fun
for me.
(And it IS fun, yes it is. I only wish I could fire up
my kiln with new tests every day instead of every
other weekend, when I have an entire day free.)
Christena Schafale on tue 31 dec 02
Kristin,
Looking at your cones again in the light of what Orton has to say, I'd
guess that you might have been at 6.5+, since your 7 is down to 3 or 4
o'clock already, and your 6 is not just touching but even beginning to
slump a little. So I'd say you were right to begin with -- a slight over-fire.
Chris
At 06:34 AM 12/31/02 -0800, you wrote:
>So, from everyone's responses, the cones at the bottom
>of my little test tube page show that I hit a good ^6?
>(Again, the cones shown are 5, 6, and 7)
>http://www.tamarac.net/alby/test_tubes/
>
>Hmmm. I had previously thought I'd overfired AND held
>too long. Now it looks as though my 30-minute hold was
>the sole culprit of my problems (my cooling rate was
>about 100* C/hour, from 1200* C to opening).
Consultation and Referral Specialist
Resources for Seniors
christenas@rfsnc.org
http://www.resourcesforseniors.com
Phone: (919) 713-1537
FAX: (919) 872-9574
1110 Navaho Dr, Suite 400
Raleigh, NC 27609
Arnold Howard on thu 2 jan 03
--- Kristin wrote:
> So, from everyone's responses, the cones at the bottom
> of my little test tube page show that I hit a good ^6?
> (Again, the cones shown are 5, 6, and 7)
> http://www.tamarac.net/alby/test_tubes/
The self-supporting cone with tip touching the shelf is very
slightly over-fired. But for most applications, I would consider it
okay.
Arnold Howard
Paragon
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