Snail Scott on thu 18 jan 01
At 11:44 AM 1/18/01 -0600, you wrote:
>Sitter cones are not cones, they are bars. Since they don't have a conical
>shape (triangular), but are square they have a completly different dynamic
>structure.
>Cullen
Just writing to point out that some sitter 'cones'
are bars, and square in section, others are in fact
shaped like conventional cones, tapered in outline
and triangular in section.
Ostensibly these tapered cones can be used to fine-
tune the firing temperature by setting them so that
the sitter rod rests on a thinner or thicker portion
of the cone. It's a pretty slim variation, though,
and nothing I make is finicky enough to bother with
such subtleties.
I haven't seen much difference in result between the
sitter cones and sitter bars of the same cone rating,
nor much difference between the various positionings
of the (tapered) cones in the sitter. Perhaps those
of you with narrow-firing-range glazes have observed
a distinction, though.
-Snail
Jonathan Kaplan on fri 19 jan 01
on 1/18/01 6:17 PM, Snail Scott at snail@MINDSPRING.COM wrote:
> At 11:44 AM 1/18/01 -0600, you wrote:
>> Sitter cones are not cones, they are bars. Since they don't have a conical
>> shape (triangular), but are square they have a completly different dynamic
>> structure.
>> Cullen
>
>
> Just writing to point out that some sitter 'cones'
> are bars, and square in section, others are in fact
> shaped like conventional cones, tapered in outline
> and triangular in section.
>
> Ostensibly these tapered cones can be used to fine-
> tune the firing temperature by setting them so that
> the sitter rod rests on a thinner or thicker portion
> of the cone. It's a pretty slim variation, though,
> and nothing I make is finicky enough to bother with
> such subtleties.
>
> I haven't seen much difference in result between the
> sitter cones and sitter bars of the same cone rating,
> nor much difference between the various positionings
Orton manufactures kiln setter bars (setter not sitter) that are
particularly designed for a Dawson kiln setter.
WHile it may be true that you many notice no difference between using an
Orton small cone or an Orton bar in your setter, the nature of the taper on
the small cones can quite appreciably effect the setter's trip
mechanism...eg the bottom or the cone being of larger profile than the
ascending taper to the narrow top, so yes, plotting the results between a
pyrometric bar versus a small cone using a sensitive digital pyrometer will
show different firing profiles.
Now the reason you may not see much difference in the glaze results is that
most glazes do have some degree of flexibility in their firing range (yes a
broad generalization).
And yes, I have used small cones in my test kiln setter when I am out of
bars, but the bars give a predicrtable result as their profile is uniform
throughout their length.
Jonathan
Jonathan Kaplan, president
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
jdkaplan@cmn.net
info@ceramicdesigngroup.net
Plant Location:
1280 13th Street Unit 13
Steamboat Springs CO 80487
(please use this address for all deliveries via UPS, comman carrier, FEd Ex,
etc.)
"Custom design and manufacturing for the ceramic arts, giftware and pottery
industries. Molds for slip casting, joggering and hydraulic pressing.
Consultation on technical issues such as clay boides, glazes, and kilns."
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