Tom Buck on thu 4 jul 96
Eric Lingren, others, have established the position of pyrometric cones
at full maturity, yet as Tony Hansen discovered, getting a consistent
cone positioning and therefore a consistent heat-work from firing to
firing is most difficult. Hansen did a series of tests, and consulted
with Orton specialists during same, and found some real problems with
cones as such. To read Hansen's report see his book, Magic of Fire 2,
either in paper or elecronic form. Go to URL
http://digitalfire.com/index.htm and follow the appropriate links for
data on the book, etc.
Cheers Tom.Buck Hamilton Canada
Mitchell Sewall on sat 9 sep 06
Maurice,
By reading your post to Tom Witman I realize you know something about cones.
Hence this question:
How come both large cones and the small ones use the same numbering system
and yet as I understand it, they go down at different temperatures?
Mitch
Maurice Weitman on sat 9 sep 06
At 16:35 -0400 on 9/9/06, Mitchell Sewall wrote:
>Maurice,
>By reading your post to Tom Witman I realize you know something
>about cones. Hence this question:
>How come both large cones and the small ones use the same numbering
>system and yet as I understand it, they go down at different
>temperatures?
Hi, Mitch,
I apologize if I gave you the impression that I knew something about
cones. Nevertheless, here comes my take on your question... I'm sure
others will pipe up as they see fit.
I assume you mean the difference between the large (full-size --
"classic" heh) cones and the small ones that one uses in a kiln
sitter.
If you mean the diff between the large cones and self-supporting,
they should be identical, but the self-supporting are, I believe,
more accurate since they are always at the proper angle. Large cones
put in a clay "cone pack" are more difficult to place and keep at the
proper angle, and angle influences the rate of drop.
Now then, my understanding is that the small cones were designed for
one purpose: to be used in kiln sitters. As such, they are meant to
be used horizontally, AND with the added weight of the sensing bar.
Therefore, if used as witness cones, they will "report" that the heat
work experienced was less than was the case. I don't really know to
what extent this would be, but it would not surprise me if a cone 6
small cone put in a cone pack wouldn't drop until cone 7 or 8, maybe
even higher.
The bottom line is, they should not be used as a reliable indication
of heat work. They may be used in that way once you've established
that you're happy with the results when a small cone X is at Y
o'clock, but the number stamped on them will not represent the true
heat work associated with that number.
I hope that was clear, and would be happy to clarify any murkiness.
Regards,
Maurice
Mary & Wes Handrow on tue 24 aug 10
This may have been asked before and answered, but I haven't found anything
yet. I was midway through a wood firing when it started to rain for hours,
all the wood was soaked and the kiln had only gotten to 1850 F., the firing
was going to cone 10. Can the old cone packs still be used or must they be
replaced, this would involve unloading the kiln to get to them. Just want
to know if I can avoid added work or is it "that's just tough"?
Lynn Wheeler on wed 25 aug 10
In one sense those are the cones to use because they will reflect the
partial heat work that your pots received. But your real question may be
"Will they accurately measure the heat work on a second firing in the same
way as a new pack of cones would?" and the answer to that is definitely no.
(I worked at Orton a while back, test firing cones for a living.) Will it b=
e
off by a lot? Probably not, depending on lots of variables, of course, but
it will be off, and you don't want to take the chance. It may not be off
much because you only got to 1850 but in the last stages of firing, cones
fall during a very narrow heat work range, which was affected by the partia=
l
firing.
If this had not happened before and you don't know how a
partial-then-full-firing affects the final results of your pots, you may
want to also take some of those half fired pieces out and replace with
unfired pots and compare those also. May discover something new. The best
thing to do would be to place new cone packs next to the old ones, do your
new firing and share the results.
My 2 cents humbly offered.
Lynn
On 8/24/10 11:43 PM, "Mary & Wes Handrow" wrote:
> This may have been asked before and answered, but I haven't found anythin=
g
> yet. I was midway through a wood firing when it started to rain for hour=
s,
> all the wood was soaked and the kiln had only gotten to 1850 F., the firi=
ng
> was going to cone 10. Can the old cone packs still be used or must they =
be
> replaced, this would involve unloading the kiln to get to them. Just wan=
t
> to know if I can avoid added work or is it "that's just tough"?
Paul Herman on wed 25 aug 10
Mary & Wes,
You can just leave the cones right where they are and fire away. They
will work fine.
I think if you had gotten closer to the end point of the firing, and
the cones had started to vitrify, then they may have read a little off.
Best wishes,
Paul Herman
Great Basin Pottery
Doyle, California US
www.greatbasinpottery.com/
On Aug 24, 2010, at 8:43 PM, Mary & Wes Handrow wrote:
> This may have been asked before and answered, but I haven't found
> anything
> yet. I was midway through a wood firing when it started to rain for
> hours,
> all the wood was soaked and the kiln had only gotten to 1850 F., the
> firing
> was going to cone 10. Can the old cone packs still be used or must
> they be
> replaced, this would involve unloading the kiln to get to them.
> Just want
> to know if I can avoid added work or is it "that's just tough"?
Ron Roy on wed 25 aug 10
Hi Lynn,
The heat work has been done to the cones and the ware so I would use
them again.
You will get more ash accumulation - I don't know what you should do
about that - fire a bit higher or a bit lower? I hope others who have
direct experience will comment on that.
RR
Quoting Lynn Wheeler :
> In one sense those are the cones to use because they will reflect the
> partial heat work that your pots received. But your real question may be
> "Will they accurately measure the heat work on a second firing in the sam=
e
> way as a new pack of cones would?" and the answer to that is definitely n=
o.
> (I worked at Orton a while back, test firing cones for a living.) Will it=
be
> off by a lot? Probably not, depending on lots of variables, of course, bu=
t
> it will be off, and you don't want to take the chance. It may not be off
> much because you only got to 1850 but in the last stages of firing, cones
> fall during a very narrow heat work range, which was affected by the part=
ial
> firing.
>
> If this had not happened before and you don't know how a
> partial-then-full-firing affects the final results of your pots, you may
> want to also take some of those half fired pieces out and replace with
> unfired pots and compare those also. May discover something new. The best
> thing to do would be to place new cone packs next to the old ones, do you=
r
> new firing and share the results.
>
> My 2 cents humbly offered.
> Lynn
>
>
> On 8/24/10 11:43 PM, "Mary & Wes Handrow" wrote:
>
>> This may have been asked before and answered, but I haven't found anythi=
ng
>> yet. I was midway through a wood firing when it started to rain for hou=
rs,
>> all the wood was soaked and the kiln had only gotten to 1850 F., the fir=
ing
>> was going to cone 10. Can the old cone packs still be used or must they=
be
>> replaced, this would involve unloading the kiln to get to them. Just wa=
nt
>> to know if I can avoid added work or is it "that's just tough"?
>
Snail Scott on thu 26 aug 10
On Aug 24, 2010, at 10:43 PM, Mary & Wes Handrow wrote:
> ...the kiln had only gotten to 1850 F., the firing
> was going to cone 10. Can the old cone packs still be used...
In my experience, cones within a few
numbers of the previous temperature
will be compromised, but all the cones
very much above will be fine. Since you
only reached 1800F, pretty much all
your cones that don't start with a '0'
will work just as you hope, including
the critical ones approaching ^10.
-Snail
Arnold Howard on thu 2 sep 10
From: "Lynn Wheeler"
> In one sense those are the cones to use because they will
> reflect the
> partial heat work that your pots received. But your real
> question may be
> "Will they accurately measure the heat work on a second
> firing in the same
> way as a new pack of cones would?" and the answer to that
> is definitely no.
----------
Lynn is correct.
You can reuse cones so long as they were fired below 100F of
maturity during the first firing. They will still bend to
maturity during the second firing, but the pre-fired cones
will slump a little earlier than fresh cones. I test-fired
015 cones this week to verify Lynn's statement.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
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