Debbie on fri 31 dec 04
Hi Mel,
Thank you for the post and pictures. This is awe inspiring work.
It seems that the clay color (seen at the bases) is very nice as well. This
is usually a down fall for oxidation work. Are you doing anything special to
the clay to achieve this besides "heavy iron"?
They are really beautiful!
Best Wishes, Debbie
>
> it is all fired in oxidization, or as close
> as i can get in my kiln.
> all fired to cone 11+.
> >
> From:
> Minnetonka, Minnesota, U.S.A.
> web site: my.pclink.com/~melpots
> or try: http://www.pclink.com/melpots
> new/ http://www.rid-a-tick.com
>
mel jacobson on fri 31 dec 04
remember, this is a glaze system that is part
of the joe and mel (mj, god, my stamp will work.)
jiang chinese glaze study. china/1125 a.d.
it is all fired in oxidization, or as close
as i can get in my kiln.
all fired to cone 11+.
the unique quality of the red is from the quality
of the iron oxide that joe has used.
we are using six different iron oxides.
the blue is iron blue crystal formation.
when one fires oxy...new colors that many
potters did not know exist emerge. (don't throw
away your electric kiln....it may become the most favored
method of firing in the next decade...
(joe koons is a ceramic engineer/chemist that has
worked for laguna clay for years.)
we fire down these kilns at 1900F for three hours.
we want the cool down to be long and slow. we are using
standard temmoku recipes...in fact, ron roy black magic is
a perfect glaze in this study. a good otto heino black. alfred
temmoku...they are all mostly the same. but, we fire
in oxidation. cone 11+
i have sent john britt a private email about
using ochre/yellow iron to get a very nice
yellow. john has done a great deal of study
in this area...oil spot etc. he is a very bright fellow.
john singer is also doing some testing for us.
he is a real `smartypants`(using his own glazes). susan karrasch has done
some electric firing for us too. cone 11.
this is very hard for many people to get into
their brains. so many potters that joe has worked
with have reduced and ruined the study.
heavy reduction of these glazes is awful.
i was very fortunate early on to realize we had
to control reduction. that was the lucky guess by
me. my dear friend rick mahaffey from washington
even dropped me a note about a friend finding the
early pots stuck in a sagger. and, without question
many of the early wood fired chinese kilns did not have
heavy reduction...they did not like it. saggers and open
flame/heavy oxygen was most favored. today's potters
that fire in wood look for ash, reduction, etc for the
that sort of quality. remember, the wonderful ming
celedons were fired in wood fired kilns. they sure
did not want runny ash. clarity...clean design, clear
glazes. (iron/celedon)
all of our work is done with only iron. no other chemical
oxides are being use. that is the point of the entire
study. see what iron does. we are going to do copper
this summer. another 400-600 pots.
we are just getting rolling.
the clay bodies are all heavy iron. just like the
old chinese pots...heavy iron clay/heavy iron glaze.
mel
kiln is full...76 pots all the same glaze.
same thickness, same layers.
we will see.
pilots are on.
From:
Minnetonka, Minnesota, U.S.A.
web site: my.pclink.com/~melpots
or try: http://www.pclink.com/melpots
new/ http://www.rid-a-tick.com
John K Dellow on sat 1 jan 05
mel jacobson wrote:
> remember, this is a glaze system that is part
> of the joe and mel (mj, god, my stamp will work.)
> jiang chinese glaze study. china/1125 a.d.
>
What you have got mate is tomato red . In Aussie we call it Shiga`s tomato red . Shiga Shigeo was a Japanese potter who lived and worked in Australia for about 10 years ,late 1960`s to 1970`s.Yes oxidation.
John Dellow "the flower pot man"
From the land down under
Home Page http://www.welcome.to/jkdellow
http://digitalfire.com/education/people/dellow/
sincultura13 on sat 1 jan 05
I have a quick question...
Mel said: "...don't throw
away your electric kiln....it may become the most favored
method of firing in the next decade..."
Are there special kilns that fire to cone 11+? If so, I'd love to
get my hand on one of them eventually. Building a wood kiln or
having a gas kiln in my area is almost impossible...
thanks in advance
Sincultura
John Britt on sat 1 jan 05
I have used a wonderful kiln by Paragon called the Dragon. It is made for
cone 10 oxidation and crystalline glazes. I am sure Arnold Howard could
tell you more, but it has heavy duty elements and 3 in soft fire bricks.
Hope it helps,
John Britt
www.johnbrittpottery.com
John Britt on sat 1 jan 05
John and others,
Yes, I agree with you that these are what we traditionally call =93tomato
reds=94 or =93kaki=94 or =93Ohata kaki=94, or =93persimmon=94, =93Iron reds=94=
, =93Iron
saturates=94, etc. It can be quite confusing to the beginner. There are many=
recipes out there already. Some also contain bone ash(Approximately 5-10%)
and lithium carbonate (approximately 1-3%) to assist the orange color.
There are already so many names for this type of glaze and my concern is
that calling a glaze =93Red Temmoku=94 will only further confuse potters. If=
we call this =93Red Temmoku=94 then we should call the same base with =BD%
iron =93Blue Temmoku=94 not Blue Celadon. And then we well have to have Oliv=
e
temmoku, Green Temmoku, Clear Temmoku=94, etc.
I have many of these recipes in my book and on page 73 there is a nice
photo of a Tracy Dotson Platter with Bailey=92s Iron Red Glaze. These are
all fired in O1 or O2. (Two firing cycles listed in the book) These can
easily be adjusted to include an oxidation soak at 1900 F as Mel suggests.
Incidentally, you can also refire kaki glazes, which have gotten brown
from too much reduction, to bisque temperature (1700 =96 1900 F), including
a soak, in either electric or gas and get an orange color. You are just
reoxidizing the iron.
Another thing on substituting types of iron, often people forget that
types of iron have varying purity, from approximately 85% - 99%. For
example, there are many sources/forms of red iron oxide, some are stronger
than others. Bayer makes some iron pigments that are very pure, synthetic
red and yellow iron. Another source is Spanish red iron, made from
bacterial digestion. Others sources of iron include: black iron, crocus
martis, barnard clay, burnt umber, sienna, etc. So direct substitution or
forms of iron is possible be it will yield different colors as the amount
of iron and impurities (silica, alumina, manganese dioxide, etc) will
vary. Then they will report that they put in 11% iron and not report the
type so you try it and don=92t get the same result. One of the best things
to do is to run line blends with the various sources of iron oxide on the
same base. (1% increments) This will clearly illustrate difference in the
purity of the iron.
John Britt
www.johnbrittpottery.com
bonnie staffel on sat 1 jan 05
OK Mel, a question came to mind. Are you firing to Cone 11 but in gas
oxidation? All of us poor schmucks who have Cone 10 electric kilns drooling
over such glazes, looks like back to the drawing board to reduce the
maturation of the glaze to fit our firing peak. Any magic answers from
those who have the RO programs on their computers? I have only done a few
Cone 10 oil spot glazes. Might be a good project for this winter to explore
Temmoku.
Warm regards,
Bonnie Staffel
http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
Charter Member Potters Council
Ivor and Olive Lewis on sun 2 jan 05
Dear Bonnie Staffel,
Happy belated birthday wishes. Hope you have a great year.
Those refractories of your cone 10 kiln will stand another couple of
cones without suffering destructive catastrophic stress.
But if you are worried about working at cone 11 when you usually work
at cone 10, then add in a slower ramp or run up to the final
temperature to add another hour or two hour of thermal work into the
glaze.
As I see things, the virtue of Mel"s current work is that he is making
certain that all of his ingredients get time to dissolve in the melt,
especially those substances that are, in truth, refractory at 1350=BA
Celsius. This ensures all materials, including those that leach from
the hot clay beneath, are all present in solution when the chemistries
that take place during his cooling schedule commence. This means,
besides having layers of differing or dissimilar glazes, he is
introducing additional layers of chemical and physical complexity.
I am sure that if someone wished to experiment they could get cone 11
glazes to melt fired to the temperature of a cone 6 firing. How? Quite
simple. Sit with the kiln for the additional time to get the joules
into the clay. Could be six, may be twelve hours. The alternative is
to "doctor" a glaze with a boron flux, between 3 - 5%
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Lee Love on sun 2 jan 05
John Britt wrote:
>John and others,
>
>Yes, I agree with you that these are what we traditionally call “tomato
>reds” or “kaki” or “Ohata kaki”, or “persimmon”, “Iron reds”, “Iron
>saturates”, etc. It can be quite confusing to the beginner. There are many
>recipes out there already. Some also contain bone ash(Approximately 5-10%)
>and lithium carbonate (approximately 1-3%) to assist the orange color.
>
I think Tomato is a good name for the iron reds. Thanks for the lithium tip John. I was intending on trying bone ash with mashiko kaki to make it more red. But adding lithium might help too.
Here is a photo of a matchawan with Hamada's red Kaki. I always figured he added something like bone ash to make it more red:
http://images8.fotki.com/v132/photos/1/199764/1600951/23-vi.jpg
--
in Mashiko, Japan http://mashiko.org
http://www.livejournal.com/users/togeika/ WEB LOG
http://public.fotki.com/togeika/ Photos!
John Britt on sun 2 jan 05
Lee,
Bone ash is what helps to make traditional Kaki's orange. I have a section
on this in my book under Iron glazes. The glazes charts are there so you
can see at a glance what the glaze type has in common. Then, in the firing
instructions you see that if you fire in heavy reuction they will be
brown. But in O1 and O2 they will be bright orange or leopard spotted
depending on the glaze. I have tiles to illustrate it.
I really know nothing about mashiko glazes, I only know that the Fake
Mashiko in the book makes a carmel glaze in reduction and an oil spot in
oxidation. Lots of possibilities.
I have taken an oil spot like Coleman Oil Spot and added bone ash (5% or
so? Can't remember precisely but I did a 1% increment line blend up to
10%) to get orange oil spots. Real nice. You could do the same with your
recipe and when you find something you like with the bone ash do another
with Lithium carbonate in 0.5% increments up to 5% or so. Be sure to try
oxidation.
Let us know what happens,
John
www.johnbrittpottery.com
Ivor and Olive Lewis on mon 3 jan 05
I have been wondering about this Iron Red.
I was introduced to it by John Coulter, a South Australian lecturer,
more than twenty years ago and there is no doubt it is a wonderful
glaze when the strident hue is contrasted against something dark, a
fact which accounts for the "presence" of the Pots Mel illustrates.
There seems to be a general folk lore opinion that Phosphorus
intensifies the hue and drifts it towards orange and we are now told
that Lithium carbonate has a similar effect.
So, the question is, can this be accounted with a chemical explanation
or is it a physical thing to do with optical qualities. Any answers
out there ? ?
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Ben on mon 3 jan 05
Ivor wrote:There seems to be a general folk lore opinion that Phosphorus
intensifies the hue and drifts it towards orange.
In a recent conversation about this with Jim Robinson He indicated (if I
understood him correctly) that phosphorous (as sometimes boron?) forms an
"immiscible" glass within the glaze, perhaps primarily affecting the ability
of the iron to remain in solution on cooling (as opposed to the optical
quality of boron clouding based in different refractory indices). It was,
to be sure a speculative conversation. Food for thought.
Ben
Back in so cal after 5 weeks in Ashland.
More Rain in Cal in 5 days than we saw the whole time up north!
Ivor and Olive Lewis on tue 4 jan 05
Dear Ben,
I would like to see Thin Section Micrographs or examine cross sections
of some of these glazes. Without some form of concrete evidence we are
just guessing about the processes of formation and the identity of the
materials which form during cooling.
Perhaps we should recall that they are styled as "Saturated Iron
Glazes". So other question to ask relate to firing temperature and
chemical reactivity. If it is high, will all of the Iron Oxide
dissolve in a silicate melt? Does the excess Iron react with
Phosphoric Pentoxide ? What are the consequences of these changes?
Thanks for your contribution.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
.
> Ivor wrote:There seems to be a general folk lore opinion that
Phosphorus
> intensifies the hue and drifts it towards orange.
>
> In a recent conversation about this with Jim Robinson He indicated
(if I
> understood him correctly) that phosphorous (as sometimes boron?)
forms an
> "immiscible" glass within the glaze, perhaps primarily affecting the
ability
> of the iron to remain in solution on cooling (as opposed to the
optical
> quality of boron clouding based in different refractory indices).
It was,
> to be sure a speculative conversation. Food for thought.
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