Marcia Selsor on wed 4 feb 04

Susan,
I use a pyrometer rather than just watching the glaze melt because I use
a lot of matt raku glazes. I fire fast and believe a cone would not have
enough "heat work" time to accurately melt when the raku glaze is melting.
Just my thought,
Marcia

Susan Giddings wrote:

> Hello,
>
> I don't understand why people don't seem to use cones with Raku firing.
> I've done Raku with and without pyrometers, with and without cones, and
> with and without both. I think the ideal is to have both, but if I had
> to choose one over the other, I think I'd rather have cones. There are
> enough instances where pyrometers are not accurate and they have no way
> of measuring "heat work", just absolute temperature. I think cones are a
> better guide to glaze melt. Yes, you can just look in at the glazes and
> see how they are melting. Raku is not so hot that seeing into the kiln
> is as problematic as it is at higher stoneware temperatures. But,
> personally, I'd rather see a cone melt just to be sure. And cones are so
> inexpensive.
>
> I was going to post this as an answer to questions asked about the need
> for pyrometers in Raku kilns and was surprised that others hadn't
> already mentioned it. And then it occured to me that there are people in
> the group I sometimes fire with that never use cones in Raku. They would
> rather go by pyrometer. I don't understand. Is there some reason why
> people choose to avoid using cones in Raku firings?

Pamela Watkins on wed 4 feb 04

Susan Giddings wrote:
clip
>There are enough instances where pyrometers are not accurate and they have no way of measuring "heat work", just absolute temperature. I think cones are a better guide to glaze melt. Yes, you can just look in at the glazes and see how they are melting. Raku is not so hot that seeing into the kiln is as problematic as it is at higher stoneware temperatures. But, personally, I'd rather see a cone melt just to be sure. And cones are so inexpensive.
**Hi Susan,

Although there is no "rule" that cones cannot be used, in a reduction atmosphere with multiple firings they are impractical and are much less accurate than a pyrometer. Instructors use them in an aid to teaching the rate of fire and the look of the glaze melt. I'm not sure what you mean by the difference in "heat work" and absolute temperature.

The majority of Raku-ers chose not to use cones or a pyrometer and have become familiar with the process, look of the glaze melt, and use a bit intuition- Intuition complements the history, spontenaity and artistic attachment
to the whole process.

As Steven Branfman says in his book Raku, A Practical Approach , "The only cones that should be used near a raku kiln are ice cream cones~Unless you are glazing with a matt or working for smoke effects where the melt could not be witnessed, and then a pyrometer is recommended." I highly recommend this book if you are firing Raku. It has been a great reference as I am just about to complete construction of a recycled Raku kiln.

Peace,
Pamela
~jaq









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Craig Dunn Clark on wed 4 feb 04

Simona, I don't see why a cone would not work. However, if you are
looking into the kiln to pay attention to what the cone is doing then you
may just as easily look at the melt of the glazes on the pots. Once you have
done it enough times the color of the kiln atmosphere is also a very good
indicator as to when to pull the pots.
As to the use of pytometers..they are also an easy way to know where you
are in the firing. As Marcia pointed out they are of particular use if you
are doing copper matts. If you are using standard crackle glazes just look
for a reflection on the pots. That's when its time to pull them.
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org

----- Original Message -----
From: "Simona Drentea"
To:
Sent: Wednesday, February 04, 2004 1:21 AM
Subject: Re: Pyrometers and Raku?


> In a message dated 02/03/2004 8:14:43 PM Mountain Standard Time,
> coneten@HOTMAIL.COM writes:
> <Is
> there some reason why people choose to avoid using cones in Raku firings?
>>
> Several of the old raku books I've been reading (even from the 80's &
early
> 90's) have said that cones are useless for raku. I've been wondering
about why
> that is, since in the class I just took, we did use cones. The instructor
> said she could tell by eyeballing the glaze too when pieces should be
pulled,
> but she did use the cones as well.
>
> Unfortunately, the books are back at the library, so I don't know what if
any
> explanation they gave. It wasn't just one book though, I read this (or saw
it
> on video) multiple times.
>
> Simona in snowy Colorado
>
>
____________________________________________________________________________
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> Send postings to clayart@lsv.ceramics.org
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