Richard Aerni on sat 17 feb 01
----- Original Message -----
From: "Jennifer F Boyer
> Hi All,
Pete's premise is that potters really
> don't have the tools to to know what's happening in the kiln
> unless they have oxyprobes.
I do have an oxyprobe, and use it for my firings. I bought it in lieu of
buying simply a high-priced, reliable digital pyrometer, because I want to
know when I make adjustments to the kiln whether it results in an immediate
drop or rise in temperature, something the cones can't really tell you.
My first few firings, I was very surprised to see how minute adjustments to
the damper could affect the reduction readings in my kiln. Really, an 1/8
inch could make a huge difference. But, ultimately, what is most important
to a potter is that you are able to chart your firings that give you the
results you want, and then be able to repeat them. The oxyprobe allowed me
to do this, BUT, what I learned is that my firings differ greatly from the
"ideal" that is plotted out in the handbook. I do a time/temperature graph
of each of my firings, with notes about temperature, humidity, tightness of
stack etc, and once you get your own "ideal" firing plotted, it's pretty
easy to follow the graph. I find the oxyprobe a very useful tool, but I
don't allow myself to become too dependent on it. They do malfunction, as
Mel implied. Nils fixed mine when it needed adjustment. But, had I
followed the numbers on it exclusively, I would have had a very weird firing
indeed. It's good to develop a sense of when your kiln is firing well, and
when it needs adjustment. The oxyprobe is a good tool to help develop this
sense, or else confirm your feelings. I'm glad I spent the money on it.
Richard Aerni
Bloomfield, NY
Robert Santerre on sun 18 feb 01
Richard,
I also do a temp/time graph of my firings from oxyprobe readings. For me it has
really dramatically shortened my learning curve for firing my new Geil kiln - a
very valuable tool. And I can reiterate that minute changes in firing conditions
(like a 1-2 mm change in damper plate position) can result in dramatic shifts in
the reducing atmosphere of the kiln. Changes I'm convinced I could never learn to
detect by conventional observations. I could probably fire the kiln now without
the oxyprobe by making adjustments that I know would throw it into heavy reduction,
but there is absolutely no way I could make fine adjustments to hold the atmosphere
at a steady 0.5 oxygen reading (medium reduction) without the oxyprobe. That may
beg the question of why one needs to be that precise, but aside from that the
oxyprobe clearly extends my human capabilities. Now I would feel a bit
"under-equipped" without it.
I also have a ditigal pyrometer on the kiln, but it is consistently "ahead" of the
oxyprobe, especially during the early and mid stages of a firing. The pryometer
seems to only come back into line with the oxyprobe and cones toward the late
stages of a firing (cone 9-10) - although part of the discrepancy may be placement
in the kiln. The pyrometer is in the upper right corner of the firing chamber
while the oxyprobe is actually in the flue (I presume measuring an average of the
temp and gas output) about 6 inches from the actual firing chamber (downdraft
kiln).
Since so many are using oxyprobes I was wondering if you or anyone else has been
able to connect the oxyprobe output directly to a computer? Seems like it should
be possible and would make preparation of those graphs a whole lot easier. Has
anyone out there had success doing this?
Bob
rfsanterre@iquest.net
////////////////////////////////////////////////////////////////////////////////////////////////////////
Richard Aerni wrote:
> ----- Original Message -----
> From: "Jennifer F Boyer
> > Hi All,
> Pete's premise is that potters really
> > don't have the tools to to know what's happening in the kiln
> > unless they have oxyprobes.
>
> I do have an oxyprobe, and use it for my firings. I bought it in lieu of
> buying simply a high-priced, reliable digital pyrometer, because I want to
> know when I make adjustments to the kiln whether it results in an immediate
> drop or rise in temperature, something the cones can't really tell you.
> My first few firings, I was very surprised to see how minute adjustments to
> the damper could affect the reduction readings in my kiln. Really, an 1/8
> inch could make a huge difference. But, ultimately, what is most important
> to a potter is that you are able to chart your firings that give you the
> results you want, and then be able to repeat them. The oxyprobe allowed me
> to do this, BUT, what I learned is that my firings differ greatly from the
> "ideal" that is plotted out in the handbook. I do a time/temperature graph
> of each of my firings, with notes about temperature, humidity, tightness of
> stack etc, and once you get your own "ideal" firing plotted, it's pretty
> easy to follow the graph. I find the oxyprobe a very useful tool, but I
> don't allow myself to become too dependent on it. They do malfunction, as
> Mel implied. Nils fixed mine when it needed adjustment. But, had I
> followed the numbers on it exclusively, I would have had a very weird firing
> indeed. It's good to develop a sense of when your kiln is firing well, and
> when it needs adjustment. The oxyprobe is a good tool to help develop this
> sense, or else confirm your feelings. I'm glad I spent the money on it.
>
> Richard Aerni
> Bloomfield, NY
>
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