Earl Brunner on tue 26 sep 00
I don't think Orton is going to lose a lot of business on
this one.
I don't think it is a bad exercise for a potter to do
though, like digging your own clay or making glazes from
local materials. Can't help but broaden your understanding
of the process and the materials.
There is a certain self-sufficient bent to it too. "I can
survive without the big guys"
Christopher Anton wrote:
>
> I confess! I'm the one who started it! :)>
> Believe me, there was no intention of trying to replace Orton cones, however
> I find an occassional "stupid question" sometimes engenders some worthwhile
> discussion which can lead to new ideas, or rediscovery of old ones. I think
> this thread did accomplish that.
>
> BTW, I knew that making cones that would perform consistently was quite an
> undertaking, but I had no idea just how complex it is. Hearing from you has
> helped me appreciate inexpensive, ready-made cones even more than before.
>
> Now if you add a Gerstley Borate substitute that performed just as
> brilliantly as your cones . . .!!
>
> - Chris
>
> ______________________________________________________________________________
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>
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--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
David Hendley on tue 26 sep 00
Making cones, at least for a serendipitous potter like myself,
is no big deal. Just make a mold, stuff the material in the
mold, and let it dry.
There may well be some variation from batch to batch, but
it is not enough to matter for a wood firing studio potter.
I test each new batch with a commercially produced cone,
and also check from time to time, just to make sure, but
there really has not been any noticeable variation.
Size and shape is very important; you must be sure to make
each cone the same thickness, with the same amount of material
each time. My first efforts were not accurate because I didn't
pay enough attention to this.
Why in the world would anyone want to make their own cones?
Well, it's kind of like asking a mountain climber why he wants
to climb a mountain: because it's there, and to see if he can
do it.
As most of you know, I am a big believer in making your own
tools and equipment.
There are three reasons for making your own tools:
(in increasing importance)
1 -- economy
2 -- creativity
3 -- education
In the case of cones, creativity doesn't enter into it much,
but it is certainly educational. Making, or having students make,
cones is a good way to show how cones are really kind of half
way between a claybody and a glaze. It is a worthwhile way
to get to know your materials better.
The economy of cone making is kind of marginal - I can make
50 cones for about 3 cents and a half hour of time.
Of course, this is after I've spent hours figuring everything
out. But that was the 'education' part of the equation.
Since I like doing lots of varied jobs more than cranking out pots all
day, I don't mind making cones occasionally.
A lot of people would hate doing this, and consider it a waste of
their time, I'm sure.
The truth is, now that I've done it a few times, I've kind of lost
interest and have reverted to buying cones. Oh well, I'm still
a more knowledgeable potter for my efforts.
Here is a copy of a couple of my postings to Clayart last year,
with my instructions and formulas for cones:
| >
| >----------------------------Original message----------------------------
| >By trail and error, I have worked out cone formulations
| >that work for ME (read this as a big disclaimer; be sure
| >to rigorously test your homemade cones for accuracy
| >before you depend on them).
| >
| >I made my mold for the cones by using Orton cones
| >to make a plaster gang mold for 6 cones. Do this by
| >laying the cones on a smooth flat surface, surrounding
| >them with a 1 X 4 'fence' and pouring in a few inches
| >of plaster.
| >My cones were sacrificed in the process. Perhaps you
| >could bisque-fire the cones first so they could be
| >used after being cast around.
| >Interestingly, in "The Potter's Alternative", by Harry
| >Davis, he says NOT to make a pyrometric cone mold
| >this way. He suggests sheet metal molds.
| >
| >To make my cones, I mix up a recipe to plastic-clay
| >consistency, slightly over-fill each space in the mold,
| >and then tamp down and remove the excess with a
| >putty knife. It's important that you don't remove too
| >much material; an undersized cone will bend at a lower
| >work-heat point.
| >Since the recipes don't have much clay in them, they
| >mixtures are pretty short, but still fine to work with.
| >I used ball clay, with it's inherent impurities, to
| >improve the workability, so this throws my formulas
| >a little off from the theoretical cone formulas.
| >A 100 gram batch makes LOTS of cones.
| >
| >
| >CONE 10
| >
| >Custer feldspar 17
| >Whiting 7
| >OM#4 ball clay 37
| >flint 31
| >(this adds up to 92)
| >
| >CaO .67
| >MgO .03
| >K2O .21
| >Na2O .08
| >Fe2O3 .02
| >TiO2 .08
| >Al2O3 1.26
| >SiO2 10.02
| >
| >
| >CONE 8 1/2
| >
| >I like this cone because it gives me a little earlier
| >warning than cone 9 for my cone 10 firings.
| >
| >Custer feldspar 22.5
| >whiting 9
| >OM#4 ball clay 29
| >flint 39.5
| >(100 total)
| >
| >CaO .69
| >MgO .02
| >K2O .21
| >Na2O .08
| >Fe2O3 .02
| >TiO2 .05
| >Al2O3 .90
| >SiO 8.96
| >
>
>
>A few years ago, I worked on a recipe for cone 06, for
>my bisque firings, but it needs some more refining, and
>I haven't worked on it in a while.
>This recipe works OK for a bisque firing, but I wouldn't
>want to depend on it for a critical glaze firing.
>These cones bend at the same time as a commercial
>cone 06, but it happens a lot faster. When the commercial
>cone is at 3 o'clock, this will still be straight up, then
>10 minutes later, when the commercial cone is at 5 o'clock,
>this one will be totally flat. Requires close monitoring!
>Another drawback is that the recipe uses Gerstley borate,
>which can be variable [and is now out of production].
>Next time, I would use a frit instead.
>
>CONE 06
>
>Redart clay 48.5
>Custer feldspar 9.0
>Gerstley borate 28.0
>whititng 10.5
>
>CaO .65
>MgO .07
>K2O .11
>Na2O .17
>Fe2O3 .08
>TiO2 .02
>B2O3 .72
>Al2O3 .31
>SiO2 2.22
>
>--
>David Hendley
>Maydelle, Texas
>hendley@tyler.net
>http://www.farmpots.com/
>
----- Original Message -----
From: Frederich, Tim
To:
Sent: Tuesday, September 26, 2000 11:19 AM
Subject: Cones and cone recipes
| To all interested parties,
|
| There has been some discussion recently on producing your own
cones.
| For those who want to try, please do so. You may find that it is more
| difficult than you thought it would be. The most important part of making
a
| cone is achieving accuracy and reproducibility so that you can rely on the
| information recieved time after time. Orton has found over 29 variables
that
| we must contend with in the production of cones. Composition is just one
| variable. Size, shape, density when pressing, binder content, moisture
| content when forming, and the purity of the water are just some of the
other
| variables that we encounter.
| After the production of the batch powder, testing is done at
several
| different heating rates and these have to match the standards at the
| National Bureau of Standards. Corrections may have to be made to the batch
| due to differences in materials. Testing is then done all over. Once the
| batch is approved, cones are pressed and then tested again.
| Other variables may also affect the bending of the cone such as
| atmosphere, hold times and the placement of the cones in the firing
chamber.
| All of the above can affect the accuracy and reproducibility of cone
| deformation.
| With the low cost of cones, it is the cheapest insurance that you
| can buy to insure quality firings time after time. Your time has to be
worth
| much more than the small amount spent on the purchase of cones for your
| firings.
|
| Best regards,
|
| Tim Frederich, Orton Ceramic Foundation
|
Frederich, Tim on tue 26 sep 00
To all interested parties,
There has been some discussion recently on producing your own cones.
For those who want to try, please do so. You may find that it is more
difficult than you thought it would be. The most important part of making a
cone is achieving accuracy and reproducibility so that you can rely on the
information recieved time after time. Orton has found over 29 variables that
we must contend with in the production of cones. Composition is just one
variable. Size, shape, density when pressing, binder content, moisture
content when forming, and the purity of the water are just some of the other
variables that we encounter.
After the production of the batch powder, testing is done at several
different heating rates and these have to match the standards at the
National Bureau of Standards. Corrections may have to be made to the batch
due to differences in materials. Testing is then done all over. Once the
batch is approved, cones are pressed and then tested again.
Other variables may also affect the bending of the cone such as
atmosphere, hold times and the placement of the cones in the firing chamber.
All of the above can affect the accuracy and reproducibility of cone
deformation.
With the low cost of cones, it is the cheapest insurance that you
can buy to insure quality firings time after time. Your time has to be worth
much more than the small amount spent on the purchase of cones for your
firings.
Best regards,
Tim Frederich, Orton Ceramic Foundation
Christopher Anton on tue 26 sep 00
I confess! I'm the one who started it! :)
Believe me, there was no intention of trying to replace Orton cones, however
I find an occassional "stupid question" sometimes engenders some worthwhile
discussion which can lead to new ideas, or rediscovery of old ones. I think
this thread did accomplish that.
BTW, I knew that making cones that would perform consistently was quite an
undertaking, but I had no idea just how complex it is. Hearing from you has
helped me appreciate inexpensive, ready-made cones even more than before.
Now if you add a Gerstley Borate substitute that performed just as
brilliantly as your cones . . .!!
- Chris
| |
|
