Reduction firing?

"Bubbles" wrote in message
...
"Annemarie" wrote in message
...


All glaze materials should be considered toxic, esp when dry, though yeah
lead etc are worse.


The glazes I use are "giftklassefrei", ie. no poison class, and are liquid
paint-on ones.

But that is not a glaze is it, just acrylic paint? Not food safe I would
think. See
http://www.lascaux.ch/english/malhil...2_mediums_.pdf

With the tiny space I have, the dust from the dry clay is
plenty enough, so I try to avoid other dry materials. Though I could
always
go outside and mix a reduction glaze and put it in a pot for painting

A way you can try it a little is in a saggar. Make a large lidded pot
out
of toothy clay fill it with sawdust and pots with reduction glazes. I
have
not personally tried it, but apparently it can work.


I've done a bit of googling about saggar, and the saggar-fired stuff I
have
found looks similar to raku, with burned patches, though these are more
brown than black.

I don't see how I would achieve reduction for the whole piece using that
technique. Also, it seems the burning of "stuff" inside may produce
poisons,
so the pieces wouldn't be food-safe?

Marianne

On Thu, 27 Apr 2006 17:10:08 GMT, "DKat" wrote:

Home Depot gives away bags of Sawdust (just bring in heavy duty plastic
bags) and they will not cut wood that has chemical preservatives in it so
what you get is chemical free (well wood is a chemical but we all now what
I'm talking about). I'm sure Lowes or other such places will happily give
it away as well.


Thanks, great tip!

I'm a bit curious on how in the world you would do this inside an apartment
or house. It is one thing to open up your electric kiln while hot but then
to put your pot in a can with burnables and not smoke up your home.... I
have never heard of anyone doing this until now. Maybe I misunderstood and
the person who suggested it in the first place had their kiln outdoors. Did
I miss something?

Actually, I had forgotten that she was talking about inside an
apartment. ;-)

However, I have heard of people sealing their saggars with
something before firing, but I'm not sure what it was. You
might even get away with using wet clay, if the mating surfaces
were previously coated with kiln wash or something so it
didn't fuse the saggar lid and body together. Anyone know
about this?



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

I can actually imagine doing the saggar reduction (well almost) but the one
that baffled me was suggesting doing a raku firing (taking the hot pot out
of the electric kiln and putting it in a tin trash can with burnables,
inside the house. Perhaps I misunderstood what that poster was actually
saying (can't find message)....

"Bob Masta" wrote in message
...
On Thu, 27 Apr 2006 17:10:08 GMT, "DKat" wrote:

Home Depot gives away bags of Sawdust (just bring in heavy duty plastic
bags) and they will not cut wood that has chemical preservatives in it so
what you get is chemical free (well wood is a chemical but we all now what
I'm talking about). I'm sure Lowes or other such places will happily give
it away as well.


Thanks, great tip!

I'm a bit curious on how in the world you would do this inside an
apartment
or house. It is one thing to open up your electric kiln while hot but
then
to put your pot in a can with burnables and not smoke up your home.... I
have never heard of anyone doing this until now. Maybe I misunderstood
and
the person who suggested it in the first place had their kiln outdoors.
Did
I miss something?

Actually, I had forgotten that she was talking about inside an
apartment. ;-)

However, I have heard of people sealing their saggars with
something before firing, but I'm not sure what it was. You
might even get away with using wet clay, if the mating surfaces
were previously coated with kiln wash or something so it
didn't fuse the saggar lid and body together. Anyone know
about this?



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

"DKat" wrote in message
...
I can actually imagine doing the saggar reduction (well almost) but the one
that baffled me was suggesting doing a raku firing (taking the hot pot out
of the electric kiln and putting it in a tin trash can with burnables,
inside the house. Perhaps I misunderstood what that poster was actually
saying (can't find message)....

People often have portable raku kilns - gas bottle and do it outside, then
the smoke etc when you thrust the piece into combustible material doesn't
matter.

"Annemarie" wrote in message
...

"DKat" wrote in message
...
I can actually imagine doing the saggar reduction (well almost) but the
one that baffled me was suggesting doing a raku firing (taking the hot pot
out of the electric kiln and putting it in a tin trash can with burnables,
inside the house. Perhaps I misunderstood what that poster was actually
saying (can't find message)....

People often have portable raku kilns - gas bottle and do it outside, then
the smoke etc when you thrust the piece into combustible material doesn't
matter.

This started out as Marianne wanting to know about doing reduction firing.
She only has is an electric kiln and not much room. I made the silly
assumption that she was limited to the indoor electric kiln (assume makes an
ass out of u and me.). So how much clearance outdoors do you think you
would need for a small raku kiln (how big a back yard)? Many years ago we
made our own but it wasn't really portable - may have been the heavy, welded
iron frame... You could certainly get away with a very small kiln for raku.
Could it be fired on a patio without burning down the apartment building???
I suppose you could insulate the trash can that you reduce the pot in...

"DKat" wrote in message
...

"Annemarie" wrote in message
...

"DKat" wrote in message
...
I can actually imagine doing the saggar reduction (well almost) but the
one that baffled me was suggesting doing a raku firing (taking the hot
pot out of the electric kiln and putting it in a tin trash can with
burnables, inside the house. Perhaps I misunderstood what that poster
was actually saying (can't find message)....

People often have portable raku kilns - gas bottle and do it outside,
then the smoke etc when you thrust the piece into combustible material
doesn't matter.

This started out as Marianne wanting to know about doing reduction firing.
She only has is an electric kiln and not much room. I made the silly
assumption that she was limited to the indoor electric kiln (assume makes
an ass out of u and me.). So how much clearance outdoors do you think you
would need for a small raku kiln (how big a back yard)? Many years ago we
made our own but it wasn't really portable - may have been the heavy,
welded iron frame... You could certainly get away with a very small kiln
for raku. Could it be fired on a patio without burning down the apartment
building??? I suppose you could insulate the trash can that you reduce the
pot in...

We had a raku kiln that was simply a trash can (nz'ers say rubbish tin
The bottom was cut out, a bit of ceramic fibre wired onto the inside of it,
then on a a few fired bricks you stack your work on small kiln shelves - we
had broken pieces, the gas bottle feeds from underneith, the whole trash can
lid and all is just lifted on and off by two people wearing gloves and with
long tongs. Then when you think it is hot enough lift the lid off and then
plunge the pieces into saw dust - we had it in a large enamel pot and put
the lid on.
We worked in the car park. I would be pretty wary of working on a deck, and
definately not inside. There is quite a lot of info on raku firing on the
net and how to make much better kilns than our trash can one.

"Annemarie" wrote in message
...
But that is not a glaze is it, just acrylic paint? Not food safe I would
think. See
http://www.lascaux.ch/english/malhil...2_mediums_.pdf


Nono. Real glazes.

http://www.rok-keramik.ch/ST1250/_st...ml/st1250.html

Marianne

Reduction misfiring in an electric kiln is bad for the elements for the
following reason:
Every time an Electric kiln is fired with a normal internal atmosphere,
a microscopically thin lair of oxide is formed on the surface of the
element.
Ultimately this layer of oxide does two things, it protects the element
itself from an attack by moisture which combined with heat is highly
corrosive, but it also reduces the working core of the element by the
same amount.
When you produce a reduction atmosphere in the kiln, that thin layer of
oxide is stripped away, leaving the element unprotected, and effectively
shortening its life.
The oxide layer can be replaced by firing the kiln up to about 800
degrees centigrade without anything in it! However some damage will have
been done during the previous firing.

As an addendum to this, most electric kiln manufacturers recommend a low
temperature firing with the kiln empty after replacing any or all of the
elements. To do so definitely increases element life.

Steve
Bath
UK


In article , tigre
writes
One Huge Snip .................................................. .....


Raku is an outside activity.

As far as reduction is concerned. Moth balls thrown into a kiln is a
possible approach. One has to be careful if they are trying this form
of reduction in electric kilns because the reduction process may
reduce/attact the heating element. Silicon Carbide in glazes work
also but needs to be tested out on the particular glaze in mind. Can
cause pinhole or craters which may have cool and interesting effect.
Firing temperature plays an important role in this process too.

Hope this helps




--
Steve Mills
Bath
UK

Hi Steve! it was good to meet you in Mashiko. I am coming to England
in July, 2nd week. Hope to see you!

Back to topic:

Not all electric kilns are created equal. Here in Japan, they tend
to cost much more. One of the reasons are the heavy elements. they
look more like glow bars than they look like thin coiled springs.
Some people have tried coating American style elements with ITC.

At the Mashiko Pottery festival last week, I sat between potters
from Kyoto and Saitama who both had beautiful reduction fired pottery
for sale. They both fire in electric, getting their reduction from
putting a charcoal filled sagger in the bottom of the kiln. I have
some pieces made by the Saitama potter I will try to photograph and put
up for folks to see.

--
Lee In Mashiko, Japan
http://mashiko.org
http://seisokuro.blogspot.com/

Bubbles wrote:
"Annemarie" wrote in message
...
But that is not a glaze is it, just acrylic paint? Not food safe I would
think. See
http://www.lascaux.ch/english/malhil...2_mediums_.pdf


Nono. Real glazes.

http://www.rok-keramik.ch/ST1250/_st...ml/st1250.html

Marianne

Ahh well what I got was in German but it also had in big letters 1250C
so yeah glaze ) When you posted before I googled the name and it
came up with paints ceramics....