Paul Lewing on fri 14 may 04
on 5/14/04 2:49 PM, Gaye Sekula at GaSeku@AOL.COM wrote:
> I guess the best way
> would be to say I am looking for ^10 reduction effects in my ^6 oxidation
> kiln.
> Yeah, I know, who isn't and I really do know that I won't be able to
> duplicate them, but I would love to be able to do what I can to get as close
> as I can.
Yeah, that's what I wanted when I made that switch. That was 18 years ago,
and I've decided I like cone 4 oxidation better for what I'm doing now. But
I do miss temmoku, and celadon, and kaki, and... Bottom line is, if you
want it to look like reduction, do reduction. If you're forced to use an
electric kiln, figure out how to use it creatively.
> M^6G's Waterfall Brown is a real good example, but I don't want to be limited
> to just that one glaze.
So use it as a starting point. Try other colorants in it. Do line blends
of other materials into it. Mix it up without one of the ingredients, then
add that ingredient back in increments till you've doubled what the recipe
calls for. Do this with each ingredient. Try other glazes over and under
it.
I like the looks a glaze has when granular ilmenite
> is added, or something that will make it speckled. I know manganese should do
> it, too, but the clay body I use already has both powdered and granular
> manganese that I feel it would be best to steer away from adding any more.
It may only take a very small amount more to make a really interesting
pattern. But you're on the right track here. Almost anything granular can
be added for interest. Try volcanic and wood ash, fine sands or ground
rocks of any kind, like the granite or marble dust you can get from
tombstone makers. Try adding iron as rust flakes. You can even calcine a
glaze until it just barely sinters, then grind it coarsely in a mortar and
pestle, sieve it to about 80 mesh, and add that.
And don't neglect applying layers of color or other glazes in thin or thick
layers. Or the effects of different cooling cycles.
I am in for what
> looks like endless testing.
If you want anything like an interesting or original glaze palette, there is
no way around that.
Oh, and a million dollars if you can spare it!
I'd settle for a dollar a test!
>
> Are my hopes too high?
"Reduction look from an electric kiln" is not too high a hope, it's just
misdirected. Aim instead for "astoundingly beautiful glazes" and forget
whether they look like what you got from a gas or wood or salt kiln.
Paul Lewing, Seattle
Gaye Sekula on fri 14 may 04
Please forgive my asking what may be a very elemental question, but what
ingredient(s), generally, make a glaze reactive? Spectrum has a line of Cone 5
Reactive glazes for use in electric kilns or reduction kilns. I have tried
several of them and really like them. Since there is a "line" there must be a way
for me to develop them, too. Is there anyone out there who wouldn't mind guiding
me in the right direction?
Please feel free to email me directly at gaseku@aol.com.
Thanks in advance!
Gaye
Paul Lewing on fri 14 may 04
on 5/14/04 8:24 AM, Gaye Sekula at GaSeku@AOL.COM wrote:
> what
> ingredient(s), generally, make a glaze reactive?
Gaye, can you be more specific about what you mean by "reactive"?
If what you mean is that these glazes typically bleed dramatically into
other glazes in a streaky or spotty pattern, it's probably not any one
ingredient or combination of ingredients that produces that result. It's
more likely that it's the balance of ingredients, particularly the ratio of
silica to alumina in the "reactive" glaze. If you're familiar with glaze
calculation software you'll know that one of the numbers that they produce
is a SiO2/Al2O3 ratio. Generally speaking, the lower the ratio, the more
matte the glaze surface will be, and the higher it is, the more glossy.
Above a certain point, a higher ratio will generally make a runny glaze.
Most usable glaze recipes have a ratio between 5:1 and 10:1. Lichen glazes
typically have a ratio below 4, and crystal glazes often have a ratio above
20.
For one glaze to bleed dramatically into another, my experience is that the
DIFFERENCE between the Si:Al ratios must be greater than 7. So, for
instance, for a glaze to bleed into a glaze with a ratio of 6:1, the other
glaze must have a ratio higher than 13:1. Since it's hard to have a glaze
that will melt at all with a ratio more than 7 LOWER than a normal glaze, my
guess is that these have glazes have a ratio more than 7 HIGHER than normal.
That means they are very high in silica and very low in alumina.
In practice this means that the "reactive" glaze by itself is likely very
runny. It also means that it is probably not a stable durable glaze.
Whether the overlap would be is anybody's guess.
Paul Lewing, Seattle
Gaye Sekula on fri 14 may 04
Hi Paul,
Thank you for answering my post. I started to answer you privately, but I am
sure there are others out there with the same question. I guess the best way
would be to say I am looking for ^10 reduction effects in my ^6 oxidation kiln.
Yeah, I know, who isn't and I really do know that I won't be able to
duplicate them, but I would love to be able to do what I can to get as close as I can.
M^6G's Waterfall Brown is a real good example, but I don't want to be limited
to just that one glaze. I like the looks a glaze has when granular ilmenite
is added, or something that will make it speckled. I know manganese should do
it, too, but the clay body I use already has both powdered and granular
manganese that I feel it would be best to steer away from adding any more. Not that
I have ruled it out for non-foodware! I realize I will have to be very careful
if I am intending any glaze to be for food use and that I am in for what
looks like endless testing. Oh, and a million dollars if you can spare it!
Are my hopes too high?
Gaye
P.S. Who knows she really needs a gas kiln and a salt kiln and a wood kiln
and a.......
Lee Love on sun 16 may 04
Paul Lewing wrote:
> Yeah, that's what I wanted when I made that switch. That was 18 years ago,
>
>and I've decided I like cone 4 oxidation better for what I'm doing now. But
>I do miss temmoku, and celadon, and kaki, and...
>
Temmoku and kaki can both be fired in oxidation. Kaki was always
fired in oxidation, along with all the other standard Mashiko glazes and
all the Oribe Mino kiln glazes.
Someone asked me off-line if Nuka could be taken to cone 6 (sorry I
didn't make a personal reply, was firing at the time.). It shouldn't
be too hard. Parts of the large noborigama might only reach as low as
this temp. The mat nukas of Hamada's are the preferred nukas. I
believe these are mat because they are underfired. (shhhh! Don't tell
the glaze Police! ;-) . )
I am guessing simply adding some flux to the synthetic
nuka recipe I have shared here would help the melt. Try G.B. or some frit.
--
Lee in Mashiko, Japan http://mashiko.org
http://potters.blogspot.com/ Commentary On Pottery
Ron Roy on fri 21 may 04
Hi Gaye,
I just talked to the head man at Spectrum (Bob) and asked him what is a
reactive glaze.
He said a glaze that has movement - I asked does that mean over fluxed - he
said no - rather that there are certain materials (oxides) that react in a
glaze to give certain effects like mottling and varied surfaces like shiny
and matte - like different phases. Rutile would be an example.
I think this is a phrase that means different things to different people -
I would think it can be related to how a glaze reacts with the clay
underneath it for instance.
It sounds like - slow cooling would make glazes more "reactive" - in other
words have more variation in surface and colour if the above descriptions
are what it really means.
RR
>Please forgive my asking what may be a very elemental question, but what
>ingredient(s), generally, make a glaze reactive? Spectrum has a line of Cone 5
>Reactive glazes for use in electric kilns or reduction kilns. I have tried
>several of them and really like them. Since there is a "line" there must
>be a way
>for me to develop them, too. Is there anyone out there who wouldn't mind
>guiding
>me in the right direction?
>Please feel free to email me directly at gaseku@aol.com.
>Thanks in advance!
>Gaye
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
kruzewski on fri 21 may 04
Dear Ron and Gaye,
I used to use a "reactive" glaze from Johnson and Matthey till they made it
impossible for anyone but big industry to get hold of. Then I had to figure
out how to make it myself - or something like.
Here comes the big thanks to Steve Mills and Mike Bailey who led me by the
nose to a lovely glaze - better than the original. They are the most
generous people.
Rutile is what makes this glaze "react" - and it's just as you describe it.
Except for one interesting point. The original Johnson and Matthey glaze was
lovely in my little top loader, but was paler and "milky" in the bigger
front loader - which of course caused many "continuity" problems. They went
up at the same rate but the cooling in the top loader is much faster. In the
end we - my college tutor Phil Mumford and I- worked out that fast cooling
improved this glaze, and slow cooling negated the reactivity. Cooling has
less of an effect on the new glaze - it's more or less identical in both
kilns.
I would also add that the glazes that use rutile in Ron and Johns cone six
book have some of the qualities of the reactive glazes I've seen and used
and would be a good starting point for your quest.
Jacqui
North Wales
----- Original Message -----
From: "Ron Roy"
> Hi Gaye,
> He said a glaze that has movement - I asked does that mean over fluxed -
he
> said no - rather that there are certain materials (oxides) that react in a
> glaze to give certain effects like mottling and varied surfaces like shiny
> and matte - like different phases. Rutile would be an example.
> It sounds like - slow cooling would make glazes more "reactive" - in other
> words have more variation in surface and colour if the above descriptions
> are what it really means.
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