John Baymore on fri 4 jul 97
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......clip....... it may be of some interest to people on the net that in
japan, and
especially in cities like kyoto, there are only electric kilns.
there is a huge misconception that there are anagamas all over
japan....sorry it is just not true. pollution controls are very tight and
potters have learned to adapt to electric firing. ......snip.......
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Actually ............ there ARE anagamas and noborigamas all over Japan.
Most of them are just no longer in use =3Cwg=3E. (That's wry grin if the
character code gremlins are still active.)
It was a sad thing, but I saw many large wood-fired kilns in many places in
Japan that are no longer being used. And as Mel mentions, plenty of
electric kilns. Is this really helping Japan's air?
The Kyoto area is in a sort of high valley plain.... a lot like Salt Lake
City, but with lower hills surrounding it. The geography of both
contributes to their air problems. When I was there (staying with a rice
farmer in Inae....near Lake Biwa) my eyes stung the entire time. The air
was terrible. And ALL of the woodkilns have been shut down for YEARS.
But then again, when I have been in the SLC area I have experienced
basically the same air quality.
Drive from SLC up through Sandy, and the air clears as you leave the
inversion. Drive up into the rural mountains surrounding Kyoto, and the
same occurs.
Even in the rural area of Mashiko air pollution was an issue. A good
portion of this came from the daily habit of all households and businesses
of burning their trash, (paper, plastic, cans, and so on) in little open
piles or in incinerators made out of steel dumpsters, and the farmers
burning great piles of rice straw and rice husks in the fields. Few
Mashiko potters are still firing completely or even the majority of their
wares with wood. Lots of gas, oil, and electric kilns.
In the case of the larger pottery villages, the potter's wood kilns were
probably a significant factor on a local scale of =22quality of life=22 as =
far
as the air goes. If you haven't been there you can't really grasp HOW MANY
POTTERS there are in concentrated areas. On a more =22global=22 scale
howerer....... it is a drop in the bucket as far as the world goes.
The real pollution source in most of these cases is simply that there are
too many people in too small an area.
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.........clip.......... It is rare for potters to create an actual reduction
atmosphere in an
electric kiln (by introducing a carbon based fuel), because the resulting
atmosphere is very corrosive to the elements. ......... snip.......=5D
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Well..... actually it is only rare at this time and in this country. I saw
it all over Japan last fall. They've been doing it for years. And a
company out of the Boston area (Reduction Production) was producing =22The
Stoker=22, an electric reduction kiln, for many, many years back in the 70's
and early 80's. While it had a few problems with even gas circulation, it
worked pretty good, all in all.
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.......zap.......but I have had several reports that the elements can have
repeated exposure to reduction atmospheres without damaging effects.
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Contrary to common belief, it takes quite a few firings in a reducing
atmosphere to destroy an electric kiln's elements. (The element resistance
will slowly increase as the wire diameter decreases.....lowering BTU output
and lengthening firing time.) The thicker the elements and the lighter the
reduction, the longer elements last. (The Stoker kiln had very heavy
guage elements.) So if you are using the minimum reducing agent to get
the job done (many potters overdo it greatly or do it at the wrong times
even in fuel kilns), and you have a kiln with larger guage element wire (or
have yours converted) you can do quite a bit of reduction firing in any
electric kiln.
Yes....... it will consume elements faster than =22normal=22 oxidation =
firing.
But elements are cheap and easy to replace. You just consider the extra
replacement cost as part of the =22cost of doing business=22 if you want to =
get
reduction effects in an electric kiln.
Also, a coating on the elements like the ITC stuff will work wonders in
extending the life in reduction. What you have if they are coated is a
little ceramic shell over the element. The element conducts/radiates heat
to the shell, and the shell radiates it into the chamber. So the element
is somewhat protected from the gaseous atmosphere in the chamber.......
depending on the exact gas permeability of the ITC ceramic shell to
reducing agents like H and CO at elevated temperatures.
(Karl...... got the equipment to test this permeability question on the ITC
coatings???)
While in Japan last fall I had the great pleasure of visiting at the Tokyo
College of Art. While there I met Muro-senesi (one of the professors) who
does incredible celadon glazed porcelains. Shimada-sensei (another
professor there whom I went to visit) showed me the kiln he used....... a
rectangular electric with a small wood firebox attached, and a lightweight
pipe flue running outside.
This electric kiln sat right next to a couple of gas kilns and an oil kiln.
He used the electric with the little wood firebox. Stellar celadon
pieces=21=21=21=21=21
The new Axner =22dual fuel=22 electric / gas combo =22Superkiln=22 sounds =
like it
has some promise in this area. It sounds like they are going about it the
right way. They are certainly correctly identifying an open market niche.
=3CBG=3E Can't wait to see one.
Best,
......................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752
JBaymore=40Compuserve.com
PS: Karl Platt's discussion yesterday of the efficiency of electric
conversion from raw fuel to resistance heating at your kiln (in response to
my posting about the woeful inefficiency of electric kilns) is IMHO a real
......MUST READ......=21=21=21 His figure of about 8=25 end efficiency is =
even a
tad lower than the 10=25 that I had understood. Check the archives.
Think about that possible 8=25 -10=25 the next time you turn on an electric
kiln. 90-92=25 of the resources you are consuming are being totally WASTED.
The only benefactor here is the people who own the centralized utilities.
Sobering thought=21
Makes gas, oil, and even (renewable) wood sound like good environmental
choices.
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