Fabienne Micheline Cassman on wed 10 jan 01
Hello :)
Tonight I can't go to bed until I post my frustration at what I just heard
recently.
First, supposedly, Orton cones are 25 to 35 degrees Farenheit margin of
error due to impurities in contained in the material used to make them and
"loose" quality control in the manufacturing process.
Combined with what I know: digital controllers are only as reliable as the
thermocouples they are attached to and their accuracy degrades after each
firing.
I'm trying to keep things are reliable as possible particularly because I
am attempting to get macro-crystals every time. I was relying on cones
until I over-fired a glaze which shouldn't have despite the cone
readings. Now, I can't rely on them either... so what's next on the
line? Guestimeter?
Something isn't right. Any comments would be appreciated. Thank you,
Fabienne
--
Milky Way Ceramics http://www.milkywayceramics.com/
Yes, I have learned from my mistakes...
I can reproduce them exactly.
Logan Oplinger on thu 11 jan 01
Cindy,
Maybe by the time our eyes go someone will have a simple device to attach to the kiln that we can dip a finger in to check temperature...like the water in a cup of tea &;)
Logan
------------------------------------------------------
Get the Latest News at CNN Interactive: http://CNN.com
Cindy Strnad on thu 11 jan 01
Fabienne,
The old masters judged their firings by the color of the heat alone. We are
fortunate to have cones and thermocouples now, however imperfect they may
be. But maybe that has crippled us in the same way that the flood of
calculators has stunted our ability to figure sums in our heads.
Maybe there is, or will be, some sort of device that can figure the
temperature of the kiln by gazing in through the peepholes to analyze the
color? Some device other than your eyes, I mean.
Do be careful not to stare too long or too close. You could damage your
eyes.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Bruce Girrell on thu 11 jan 01
Cindy Strnad wrote:
> Maybe there is, or will be, some sort of device that can figure the
> temperature of the kiln by gazing in through the peepholes to analyze the
> color? Some device other than your eyes, I mean.
That would be called an optical pyrometer. See for example
http://www.spectrodyne.com/
Bruce "was I first?" Girrell
Ruth Ballou on thu 11 jan 01
Draw tiles come to mind...... but the peeps in your kiln probably aren't
large enough for this to be feasible. Could they be enlarged?
Ruth
>Hello :)
>
>Tonight I can't go to bed until I post my frustration at what I just heard
>recently.
>
>First, supposedly, Orton cones are 25 to 35 degrees Farenheit margin of
>error due to impurities in contained in the material used to make them and
>"loose" quality control in the manufacturing process.
>
>Combined with what I know: digital controllers are only as reliable as the
>thermocouples they are attached to and their accuracy degrades after each
>firing.
>
>I'm trying to keep things are reliable as possible particularly because I
>am attempting to get macro-crystals every time. I was relying on cones
>until I over-fired a glaze which shouldn't have despite the cone
>readings. Now, I can't rely on them either... so what's next on the
>line? Guestimeter?
>
>Something isn't right. Any comments would be appreciated. Thank you,
>
>Fabienne
>--
>Milky Way Ceramics http://www.milkywayceramics.com/
>
> Yes, I have learned from my mistakes...
> I can reproduce them exactly.
>
>______________________________________________________________________________
>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.
Fabienne Micheline Cassman on fri 12 jan 01
At 07:08 PM 01/11/2001 -0700, you wrote:
>"First, supposedly, Orton cones are 25 to 35 degrees Farenheit margin of
> >error due to impurities in contained in the material used to make them =
>and
> >"loose" quality control in the manufacturing process"
>
>I do not believe the figures mentioned above are any near accurate. If =
>memeory serves, there was a post not too far back, from Tim at Orton, I =
>think he stated that the margin of error was only +/- 3 or 4 degrees F.
Here is an update of some comments which I found useful for my journey in
coming to term with the recent cone information I came across. Common
sense would point to the cones being more reliable, perhaps as reliable as
CraigD (?) states. Also, one person who visited the Orton facility was
impressed by their testing for consistency.
It has been suggested that the 25 to 35oF discrepancy is only temperature
at a point in time rather than heat work related; I am trying to confirm
which way this was intended. I read it as being heat work although the
difference is probably ill worded. If it is indeed temperature then the
statement would result invalid.
I am also trying to find out the source of this statement and if there is
data to support it.
In terms of controllers, a good point was raised: they are consistent in
their error and the degradation is subtle from firing to firing which makes
it easy to keep up with. The only thought I am left with is when new
thermocouples are installed, the ball game starts all over in terms of
figuring out the beast. :)
Thank you for all who help me with this. I'll post again when/if I get a
revelation on cones :)
Fabienne who tries to test everything, measures twice, and cuts once.
--
Milky Way Ceramics http://www.milkywayceramics.com/
Yes, I have learned from my mistakes...
I can reproduce them exactly.
Paul Taylor on sun 14 jan 01
Dear Fabienne
That's a nice name .
I expect the potter that came to the mistaken conclusion that Orten cones
are often inaccurate had a similar experience to my self but did not
investigate.
Some time ago I also thought Orton cones were unreliable because The cone
8 I bought did not bend at the temperature I was used to. I complained to
Orton Who sent me a box of cone 8b Which worked fine . What I expect had
happened was that I had for years been using a stash of Orton cones that
were differently labeled - the boxes could have been over thirty years old.
They could have been traveling from Orton to my kiln for so long that the
labeling regime at Orton had changed or somehow the B reference had gone
missing on the boxes in storage . Now I will have to buy some more 8Bs and
hassle my supplier yet again for something different.
Orten dealt with my letter by return of post including a box of the right
cones for free for me to check to see that their diagnosis of the confusion
was right . I was amazed by the good courtesy and efficiency that Orton
showed; that sort of manners is a a dying art in Europe. Any body writing
to me has to wait weeks while I remember where I put the stamps and the
letter spends a few days on the dash board of my car .
So I doubt if a company that employs such efficiency would be manufacturing
cones that differ by thirty degrees and the cones they sent me bend at
exactly the old temperature.
My thermocouple and pyrometer far more unreliable. They are eighty
degrees out; according to those two liars I fire to 1180 centigrade. At the
time I could not complain to the company that sold me the dodge equipment
because of pressure of work. I made a little conversion chart and now I am
so used to them I would have difficulty if I replaced them.
As I write this reply I am thinking that most of my pottery runs in this
excentric way and that nothing works as it should - but I am too happy to
worry.
Regards from Paul Taylor
http://www.anu.ie/westportpottery
> From: Fabienne Micheline Cassman
> Reply-To: Ceramic Arts Discussion List
> Date: Wed, 10 Jan 2001 22:25:07 -0600
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Cones Reliability
>
> Hello :)
>
> Tonight I can't go to bed until I post my frustration at what I just heard
> recently.
>
> First, supposedly, Orton cones are 25 to 35 degrees Farenheit margin of
> error due to impurities in contained in the material used to make them and
> "loose" quality control in the manufacturing process.
>
> Combined with what I know: digital controllers are only as reliable as the
> thermocouples they are attached to and their accuracy degrades after each
> firing.
>
> I'm trying to keep things are reliable as possible particularly because I
> am attempting to get macro-crystals every time. I was relying on cones
> until I over-fired a glaze which shouldn't have despite the cone
> readings. Now, I can't rely on them either... so what's next on the
> line? Guestimeter?
>
> Something isn't right. Any comments would be appreciated. Thank you,
>
> Fabienne
> --
> Milky Way Ceramics http://www.milkywayceramics.com/
>
> Yes, I have learned from my mistakes...
> I can reproduce them exactly.
>
| |
|
