Karen Sullivan on mon 25 jul 11
I fire a charcoal kiln...
so I fire a kiln that is tumble stacked...
with the pieces held in place with wadding...
I fire to cone 10, and then throw in 100
lbs of charcoal...that filters through the
work...after the charcoal goes in, I throw
in about a gallon of water...
so my hydrogen reduction...
the process brings out color in the
stoneware...
I have looked for info about the process....
Pamela Van Diver at the Smithsonian
published an article about historical
hydrogen reduction practices in
ancient wood kilns...
but it was to technical and I did
not understand the text...
If you would explain what happens to
me...in a way I could understand I would
be grateful...
thanks
karen
John Britt on mon 25 jul 11
Karen,
What was the name of the article?
johnbrittpottery.com
Fredrick Paget on mon 25 jul 11
Karen,
The chemical reaction you initiate when you put water into a hot kiln
containing charcoal is the same as what is known as the producer gas
reaction. The steam from the water introduction reacts with the hot
carbon (charcoal) and makes hydrogen and carbon monoxide. These are
both reducing agents. The Chinese of old did this to make the tiles
used on roofing, They actually built kilns with a depression on the
top where water was pooled and soaked through the roof into the kiln
when at high temperature.
Some years ago I downloaded a PhD dissertation explaning how to
introduce hydrogen to a kiln with out blowing it up. It was said that
if the kiln was filled with air and hydrogen it would explode unless
the hydrogen was less than 5 percent concentration. By filling it
with nitrogen containing 5 percent hydrogen he was able to get
reduction.
Unfortunatly because of changes to the Apple operating systems (3
times over the years) it is burried in files I can access only by
using an ancient Classic Apple system that I don't think I have
turned on for 10 years.
I was always wanting to try this hydrogen reduction but as I have a
history of having blown myself up three times experimenting with
chemicals as a youth I haven't tried it.
At the place I worked for many years as an electrical engineer the
engineer in the next lab had a hydrogen reduction furnace. Our
factory was provided with a piped in hydrogen supply from a huge tank
out in back as we used oxy-hydrogen torches to hand work quartz to
make what are called HMI lamps. These are arc lamps made of pure
quartz (transparent and vitrious). They are used in TV studios.
The lead in wires are sealed to the quartz and are molybdenum. It
had to be clean and oxide free. They used this reduction furnace to
fire the wires in pure hydrogen.
The furnace was a 6 inch electrically heated square fire clay tube
about 4 feet long and was filled with pure hydrogen. There was a
swinging door at each end and hydrogen was escaping and burning at
the ends through cracks. There was a pilot light at each end and it
kept the escaping hydrogen lit. Since there was no oxygen or air
inside it was just burning quietly. When the door was opened to
access the inside the hydrogen escaped faster but it was repentished
by the piped in hydrogen and merely came out as a flame that curved
upward out of the way.
Fred
> I fire a charcoal kiln...
>so I fire a kiln that is tumble stacked...
>with the pieces held in place with wadding...
>I fire to cone 10, and then throw in 100
>lbs of charcoal...that filters through the
>work...after the charcoal goes in, I throw
>in about a gallon of water...
>so my hydrogen reduction...
>the process brings out color in the
>stoneware...
>
>I have looked for info about the process....
>Pamela Van Diver at the Smithsonian
>published an article about historical
>hydrogen reduction practices in
>ancient wood kilns...
>but it was to technical and I did
>not understand the text...
>
>If you would explain what happens to
>me...in a way I could understand I would
>be grateful...
>
>thanks
>karen
--
Fred Paget
Twin Dragon Studio
Mill Valley, CA, USA
fredrick@well.com
Charter Member Potters Council
James Freeman on mon 25 jul 11
A Forward Recoil Energy Spectroscopy (FRES) Test of Hydrogen Reduction as =
a
Strategy for Firing of Chinese Ceramics Author:Levine, TimVandiver, Pamela
B. Mayer, James W. Editor:Vandiver, Pamela B.Druzik, J. R. Madrid, J.
L. G.Freestone,
I. C.Wheeler, G. S. Object Type:Smithsonian staff publicationElectronic
document Year:1995 Citation:Materials Issues in Art and Archaeology IV, pp.
167-186
Hydrogen Reduction as a Strategy for Firing of Ancient Chinese Ceramics
Hydrogen reduction is commonly thought to be a process developed for
European steelmaking practice in the industrial revolution. However, this
firing strategy was used for ceramics in China dating to the 16th century
and probably to the Han dynasty (206 B.C.-A.D. 220) and earlier. A two- to
three-fold increase in hydrogen concentration occurs on the surface of
modern and ancient brick and roof tiles, evidence that they were bathed in =
a
hydrogen-rich atmosphere. This increase was measured using forward recoil
energy spectrometry (FRES), a new technique for semiconductor research
developed at Los Alamos National Laboratory.
The production of gray brick and roof tile has been significant in China fo=
r
two millennia and was used as a way of identifying Chinese installations in
Siberia and on the northern and western frontiers of China, as opposed to
the red brick made by peoples to the west. The first clear literary evidenc=
e
of this special firing procedure is contained in a 17th century A.D. text
that shows water being introduced into a kiln. Study in collaboration with
the Shanghai Institute of Ceramics of similar modern kilns making gray tile
and brick in both urban and village contexts has shown a special
three-regime firing schedule. To achieve the gray color, the kiln is charge=
d
with extra fuel, then closed at the firebox and flue openings, and water is
introduced from a pool on the roof without subsequent introduction of air.
The water dissociates, as has been described for water gas firing or water
smoking in steel production.
The results of this firing produce bricks that are distinctive not only for
their color but for their microstructure, which indicates that further
sintering has occurred, strengthening the bricks. In future studies in
collaboration with the Freer and Sackler Galleries of Art, CAL researchers
hope to investigate the possible presence of this specialized technology in
the Neolithic period in China.
Hope it helps.
...James
James Freeman
"...outsider artists, caught in the bog of their own consciousness, too
preciously idiosyncratic to be taken seriously."
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Mon, Jul 25, 2011 at 1:22 PM, John Britt wro=
te:
> Karen,
>
> What was the name of the article?
>
> johnbrittpottery.com
>
ivor and olive lewis on tue 26 jul 11
To achieve a Water Gas Reaction it is necessary to have a reaction chamber
temperature well above 1000 Deg C (1832 deg F). Free Carbon reduces
superheated steam ( or if you wish Water oxidises Carbon ) and the result i=
s
a mixture of Pure Hydrogen and Carbon Monoxide. This is an endothermic
reaction causing rapid cooling. Energy is needed to effect and support the
reaction which slows down and eventually ceases.
To ensure continuous production of the reducing gases (Hydrogen and Carbon
Monoxide) Air is blown in with the water. This air helps to burn Carbon (as
charcoal). Burning Carbon causes an exothermic reaction and restores the
temperature of the reaction to a more productive and profitable level. The
resulting gas which is fed into the furnace to burn as fuel of into a kiln
to induce reduction transmutations is now rich in Nitrogen and is known as
Producer Gas. Producer Gas has a lower calorific value when compared to
Water Gas.
When I was firing with Oil I would get a build up of carbon in the fire
ports during periods of reduction. I used a weed sprayer and water to
disrupt and dissipate this obstruction.
Ask Tony Clennel about his wet wood firings.
Regards,
Ivor Lewis,
REDHILL,
South Australia
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