search  current discussion  categories  kilns & firing - cones & controllers 

rookie mistake -- using witness cones -- can't see them

updated sat 23 jul 05

 

Mary/Adams on thu 21 jul 05


It was advised to not depend on the kiln sitter and to rely on witness
cones. I use plenty of witness cones but have a really hard time seeing
them. It is either too bright (and I do use UV sunglasses) or it's too darn
dark. I have tried a laser pointer and that helps a little. Any
suggestions?

Mary

Arnold Howard on thu 21 jul 05


From: "Mary/Adams"
>I use plenty of witness cones but have a really hard time seeing
> them. It is either too bright (and I do use UV sunglasses) or it's too
> darn
> dark. I have tried a laser pointer and that helps a little. Any
> suggestions?

Mary, here is the method I use to see witness cones:

If you position cones just right, you can see them even at cone 10, when the
kiln interior turns white-hot.



In formulating these guidelines, I tested a welder's facemask, mirror, and
high intensity flashlight. You don't need those items, even for cone 10
viewing.



1) Place the cones 8" - 12" away from a peephole. Positioning them closer
makes them very difficult to see.



2) Have enough space around the cones to keep them from touching a piece of
ware when they bend.



3) Position cones so that when viewed from the peephole, they are
silhouetted by an element on the opposite kiln wall. (Keep cones at least 2"
from an element.) The element that silhouettes the cones should be level
with the lower part of the cone. If the element is in line with the upper
part of the cone, you won't be able to see the cone when it bends.



4) If you use the three-cone system, always have the higher temperature cone
on the same side in every firing. Otherwise you can lose track of which cone
is which.



5) Wear firing safety glasses when viewing the cones through the peephole.
So far my favorite glasses are green #3.



Sincerely,



Arnold Howard

Paragon Industries, L.P., Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com

William & Susan Schran User on fri 22 jul 05


On 7/21/05 1:26 PM, "Mary/Adams" wrote:

> . I use plenty of witness cones but have a really hard time seeing
> them. It is either too bright (and I do use UV sunglasses) or it's too darn
> dark. I have tried a laser pointer and that helps a little. Any
> suggestions?

I already know we've gone over this and folks have written in about the
issues with what I'm about to write, but it works for me.

I have the cones close to the spy hole and I simply blow on them. I never
have any issues with seeing the cones. Blowing on them cools the edges,
making them easier to see.

I know folks will say if you blow ion them they will give inaccurate
readings or you'll blow brick debris in the kiln.

I have also placed cones on the back of the shelf, away from the spy hole
and they are bent exactly the same as the ones I blew on.


--
William "Bill" Schran
Fredericksburg, Virginia

Jim Willett on fri 22 jul 05


On 7/21/05 1:26 PM, "Mary/Adams" wrote:

> . I use plenty of witness cones but have a really hard time seeing
> them. It is either too bright (and I do use UV sunglasses) or it's
> too darn dark. I have tried a laser pointer and that helps a little.
> Any suggestions?

We're sure this topic was cussed and discussed just a couple of weeks ago.
In this case, Mary, the archives will serve you well. We were going to add
however that we don't have the problem as we have no cones in our
studio....but then while cleaning up this week I did find a box of 06 cones.
Now we can't remember what we used them for. For our electric fired
oxidation process we fire time and temperature, load after load after load,
week after week, after week with no cones in the kiln. We are familiar
enough with our clay body, glazes, and kilns we know if we have under or
over fired by looking at the first pot out of the kiln, and that very seldom
happens. This is not meant to be instructional, just informative. It works
for us in our situation. As a beginner learning the process cones are a
valuable tool, and used correctly will assist you to find the
clay/glaze/temperature combination(s) you are looking for. Should we have an
unexplained change in appearance or performance we would be down at
Plainsman Pottery Supply picking up some Orton cones as well.

Jim and Cindy
Out of the Fire Studio
http://www.outofthefirestudio.com

This message has been processed by Firetrust Benign.

Snail Scott on fri 22 jul 05


At 10:26 AM 7/21/2005 -0700, you wrote:
>It was advised to not depend on the kiln sitter and to rely on witness
>cones. I use plenty of witness cones but have a really hard time seeing
>them. It is either too bright (and I do use UV sunglasses) or it's too darn
>dark. I have tried a laser pointer and that helps a little. Any
>suggestions?


Try a piece of dark glass, of the sort sold
for welding helmets. A #5 is about as dark as
you would want. No ligher than #3. You don't
need a whole welding helmet or even goggles;
just look through the piece of glass. Cheap
and easy.

There will be a million other suggestions,
too, and most of them work fine.

-Snail