Joseph Herbert on sat 25 oct 97
Marley Wolhud is trying to balance the relative merit of kiln types. So who
doesn t or hasn t? Starting at the most basic part of the question: if you
don t have a kiln, you can t be a potter. Yes, the clay is nice and
necessary, Theory of form and function is invigorating, but if it ain t
fired, it ain t a pot. Watching unfired clay sculpture melt in the rain is
fine for the conceptual art crowd, but it ain t pottery. So There. That
makes the answer to the first part of the question: Yes, you need one (or
access to).
Second part: what kind? Two classes fueled and unfueled (not a real term
since most electricity is produced from burning fossil fueled plants, a
quibble in this discussion). The fueled kilns are chemical reactors. The
atmosphere of the fueled kilns is an active chemical agent in the production
of the ware. This activity can only be partially avoided by placing the ware
in saggars (closed containers) to protect them from the "fuel fumes".
Un-fueled kilns are usually electric ( you can throw solar kilns in this
category) and the kiln atmosphere does not take an active part in the
chemistry of the ware. Since ceramic materials are, by definition, oxides,
the neutral or oxidizing atmosphere of unfueled kilns has no appreciable
chemical effect.
Why are there so many electric kilns advertised? Mostly because they are
easy to make so many people do. The construction and use of electric kilns
is relatively simple. The kiln is an insulated box with electrical
resistance heating elements inside. Depending on the insulation of the kiln
and the melting temperature of the elements, these kilns could
(theoretically) reach any temperature below the melting temperature of the
heating elements. In fact, a kiln that used the radiation from an electrical
arc as the source of heat could reach very high temperatures indeed. (4,000
degrees?) In any event, the kilns that can reach the temperatures we usually
use in our clay adventures are easy to make. The insulating fire brick,
ni-chrome heating elements, other electrical parts, and sheet metal are
easily available. The second part of the urge to manufacture is that these
can be treated as electrical appliances - turn it on - turn it off. Within
limits, the required operator knowledge to successfully fire an electrical
kiln is low. Put the stuff in, leave it on this long, it is hard when it
comes out. Pottery.
Fueled kilns are a different kind of thing. The possible results of firing
are highly variable, the dangers of improper operation of much greater, the
range of effects from firing are much wider. Proper operation is imperative
and operator skill requirement is high. As I said above, a fueled kiln is a
chemical reactor and the operator controls the chemical constitution of the
atmosphere in the kiln which has a great effect (sometimes disastrous) on the
ware inside. The "Reductions" that fueled kiln operators speak of are mostly
real chemical events where the carbon monoxide in the kiln atmosphere draws
oxygen from the body and glaze constituents. The resulting changes are
spectacular - copper red instead of green or brown or black. "Toasty" brown
bodies. On and on. The look of these effects is possible in an electric
kiln but the chemical effect is not.
The range of fueled kilns types and practices is wide. Fuels are mostly
hydrocarbons or wood. People fire with natural gas, heating oil, propane,
LNG, and wood. Other fuel choices, like coal, waste paper, used vegetable
frying oil, manure, straw, saw dust, corn stalks, old tires, or hydrogen are
less frequently used. The choice of fuel is related to the availability of
the fuel, the ease of use, the quality of results and the cost of the
operation. If a troublesome fuel is "free" it is more attractive than an
easy to use fuel that is expensive. There are probably "free fuels" in your
area, if you are willing to go to the trouble of using them.
Fueled kilns range from rapidly fired raku kilns that use natural gas or
propane and fire in an hour to wood fired, oriental type kilns that fire for
days with acolytes constantly in attendance. The results are wildly
different and the effort required is too. Which of these poles you are drawn
to depends on your particular clay dementia.
So many fuels, so little money. There are groups of people who declare that
some particular fuel is, on the basis of aesthetics, philosophy, or elitism,
the best and only "meaningful" fuel to use for firing. There are others that
don t care. The effects produced by the addition of ash from the fuel by
firing for days with selected logs are very attractive and meaningful to
some. Others think you could just spray some ash on and fire it with gas in
14 hours. The actual fuels people end up using in their kilns is very
personal and very much tied to their local environment and economy. There
are more wood fired kilns in rural North Carolina or Pennsylvania than in
Nebraska or New York City. There is a personal economy factor too. Some
fuels are more expensive to use that others and some require very different
kiln designs. Few individuals have a collection of differently fueled kilns.
Some do, but the cost of these adventures is high. The artist doesn t count
the cost, but April is coming.
This is all fine, but what should one buy? If you aren t going to be a
single firer or pit firer, you need an electric kiln for bisquing. It is
possible to use a fueled kiln for bisquing but the ease of use of the
electric kilns makes them the tool of choice for that. The electric you
choose will probably be based on the price and on recommendations of users.
Some electric kilns have troublesome design defects that don t change the
result of the firing but do make them a pain to own.
You might remember that there are many disappointed in the
hoped-for-love-affair with clay. Many of these rejected suitors or brides
left at the alter have purchased electric kilns that they only retain now as
a monument to their lost love. If you find one of these disappointed souls
and offer their symbol of lost art a good home, you can get it pretty cheap.
Do you really care what brand it is if it once contained the entire artistic
dreams of another human?
Joseph Herbert
JJHerb@aol.com
Michelle H. Lowe on sun 26 oct 97
>Why are there so many electric kilns advertised? Mostly because they are
>easy to make so many people do. The construction and use of electric kilns
>is relatively simple.
I have a question about electric kilns.
Last year at a meeting of our local clay club, a couple members talked and
showed slides of their visit to Italy, where they had taken the majolica
course offered each summer. One thing that really made me wonder was the
description of their electric kilns. Apparently the kiln design they had,
enclosed the elements in the channels of softbrick so they are not exposed
to the atmosphere of the kiln, thus enabling the firers to use reduction in
electric firings with ease.
This seems such a simple, logical solution to firing reduction in electric,
it surprises me that no manufacturers have done anything similar in this
country! Is anyone familiar with these types of kilns?
What would be problems inherent with this type of design that would keep us
from using kilns like this?
Mishy, making teapots and pasta plates
Michelle Lowe, potter in the Phoenix desert \|/ |
mishlowe@indirect.com -O- | |
mishlowe@aztec.asu.edu /|\ | | |
|_|_|
http://www.amug.org/~mishlowe ____ |
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( )
<__>
June Perry on mon 27 oct 97
Dear Mish:
Expense could be one of the reasons. Years ago I read about and you can still
find ads for globar elements. These are more expensive than kanthal wire but
are impervious, supposedly, to reduction firings.
One one of my trips to Japan, I visited Kyoto University ceramics department.
They had an electric kiln with these elements that laid flat against the wall
going up and done in a zig zag fashion. They fired with electric and then
finished with wood in this particular kiln. I don't know though if the
elements were globar or kanthal just installed flat instead of wound round or
another form of element. Maybe one of the other clayarters can fill in that
part.
I remember reading about a globar kiln years ago, that had a little pull out
tray for introducing either charcoal briquettes or moth balls as a reduction
medium. I did several tests with both of those and never got good reduction.
Of course this was in my baby step stages of learning pottery twenty five
years ago. I never pursued it past a few tries because it didn't seem worth
the trouble and soon after that I moved out of the city and into the country
and built my first downdraft gas kiln based on one of the kilns in the Daniel
Rhodes book.
Regards,
June
Paul Monaghan on tue 28 oct 97
Michelle H. Lowe wrote:
>
> ----------------------------Original message----------------------------
> >Why are there so many electric kilns advertised? Mostly because they are
> >easy to make so many people do. The construction and use of electric kilns
> >is relatively simple.
>
> I have a question about electric kilns.
>
> Last year at a meeting of our local clay club, a couple members talked and
> showed slides of their visit to Italy, where they had taken the majolica
> course offered each summer. One thing that really made me wonder was the
> description of their electric kilns. Apparently the kiln design they had,
> enclosed the elements in the channels of softbrick so they are not exposed
> to the atmosphere of the kiln, thus enabling the firers to use reduction in
> electric firings with ease.
>
> This seems such a simple, logical solution to firing reduction in electric,
> it surprises me that no manufacturers have done anything similar in this
> country! Is anyone familiar with these types of kilns?
> What would be problems inherent with this type of design that would keep us
> from using kilns like this?
>
> Mishy, making teapots and pasta plates
> Michelle Lowe, potter in the Phoenix desert \|/ |
> mishlowe@indirect.com -O- | |
> mishlowe@aztec.asu.edu /|\ | | |
> |_|_|
> http://www.amug.org/~mishlowe ____ |
> -\ /-----|-----
> ( )
> <__>
Hi Mishy,
Believe it or not it's done everyday in Heat Treat ovens and commercial
corrosive atmosphere kiln/ovens. It's just more expensive. many of
these use Calrod sealed elemnts like the burners on your electric range
or oven.
Paul :-))
BTW download the FREE computer book for your kids and the homeschoolers
from our site.
Paul :-))
--
Paul J. Monaghan email: paul@web2u.com
WEB2U Productions --- http://www.web2u.com
The "COOLEST" Site on the WEB
"The Computer Secrets are hidden at http://www.web2u.com/secret"
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