Earl Krueger on thu 8 sep 05
On Thu, 2005-09-08 at 12:02 -0500, dannon rhudy wrote:
> I have made many oil-spot glazes at cone 6,
Whaaaaat ???
Everything I've read says that you need to reach a temperature about
cone 9 in order for the iron oxide to auto-reduce, which is what
produces the oil spots.
Is this not true ???
If Dannon says she's done it at cone 6, I'll believe her and go start
making up some test batches. Lots of throwing practice pots have been
waiting for a purpose like this.
One more example of not believing everthing you believe to be true.
--
earl k...
bothell, wa, usa
Dayle on thu 8 sep 05
I just came across the 6/03 'conversation' regarding David Hewitt's (UK)
success with oil spot glazes in oxidation at cone 9. He mentioned that he
would share his recipe with Linda Knapp(UK). I use porcelain clay bodies
and fire in a 3 year old L&L kiln that does not reach a true cone 10 even
with elements in the bottom of the kiln. The latest Sept./Oct. issue of
Clay Times has an article on Dorothy Davis's oil spot glazed pieces. Even
though the recipes given are for cone 10, I noticed that the pieces shown in
the article were all fired at cone 11. Is there a technique for producing
oil spot glazes in oxidation at cone 9?
dannon rhudy on thu 8 sep 05
I have made many oil-spot glazes at cone 6,
oxidation, without difficulty. You just need
to lower the melting point of your glaze to a
temp you can achieve with your kiln. Use
any recipe you have. I've done some Harding
Black recipies (via John Britt article/Clay Times).
regards
Dannon Rhudy
----- Original Message -----
From: "Dayle"
To:
Sent: Thursday, September 08, 2005 9:49 AM
Subject: Oil Spot Glaze at ^9
> I just came across the 6/03 'conversation' regarding David Hewitt's (UK)
> success with oil spot glazes in oxidation at cone 9. He mentioned that he
> would share his recipe with Linda Knapp(UK). I use porcelain clay bodies
> and fire in a 3 year old L&L kiln that does not reach a true cone 10 even
> with elements in the bottom of the kiln. The latest Sept./Oct. issue of
> Clay Times has an article on Dorothy Davis's oil spot glazed pieces. Even
> though the recipes given are for cone 10, I noticed that the pieces shown
in
> the article were all fired at cone 11. Is there a technique for producing
> oil spot glazes in oxidation at cone 9?
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
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> You may look at the archives for the list or change your subscription
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melpots@pclink.com.
>
Tony Ferguson on thu 8 sep 05
Dannon,
Do you have any pictures of these? With details?
Tony
dannon rhudy wrote:
I have made many oil-spot glazes at cone 6,
oxidation, without difficulty. You just need
to lower the melting point of your glaze to a
temp you can achieve with your kiln. Use
any recipe you have. I've done some Harding
Black recipies (via John Britt article/Clay Times).
regards
Dannon Rhudy
----- Original Message -----
From: "Dayle"
To:
Sent: Thursday, September 08, 2005 9:49 AM
Subject: Oil Spot Glaze at ^9
> I just came across the 6/03 'conversation' regarding David Hewitt's (UK)
> success with oil spot glazes in oxidation at cone 9. He mentioned that he
> would share his recipe with Linda Knapp(UK). I use porcelain clay bodies
> and fire in a 3 year old L&L kiln that does not reach a true cone 10 even
> with elements in the bottom of the kiln. The latest Sept./Oct. issue of
> Clay Times has an article on Dorothy Davis's oil spot glazed pieces. Even
> though the recipes given are for cone 10, I noticed that the pieces shown
in
> the article were all fired at cone 11. Is there a technique for producing
> oil spot glazes in oxidation at cone 9?
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Tony Ferguson
...where the sky meets the lake...
Duluth, Minnesota
Artist, Educator, Web Meister
fergyart@yahoo.com
fergy@cpinternet.com
(218) 727-6339
http://www.aquariusartgallery.com
http://www.tonyferguson.net
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dannon rhudy on fri 9 sep 05
Subject: Re: Oil Spot Glaze at ^9
I've gotten quite a number of requests/responses/
remarks regarding the oil spot glazes I have done
at cone 6.
Here's what I did. I read an article in Clay Times
by John Britt. The article was an excerpt from his
book. There was an Oil Spot/Harding Black recipe
in the article, made for cone 9-10 reduction. I took
the glaze and lowered the melt point to try it at cone
6 oxidation. It looked just like it looks at cone 10.
Pics in article, Jan/Feb 2005.
However, I am not sure that it is a true "oil spot".
It has an underglaze, and an overglaze, or two glazes
one put on top the other, and the oil spot effect is
really the under glaze showing through the over glaze.
On two occasions the glaze
broke up in a very interesting way, with tiny freckles of
cream, brown, black, rust and dark blue, where the layering
was. The other oil spot glaze I've tried at cone 6/oxidation
is not my glaze, and in fact I don't know what is in it.
I was sent some pre-mixed powdered cone 10 glaze,
altered it to fire at cone 6, glazed some tests and - they
look like some oil spot glazes I have seen. They do
NOT look like the black-on-black oil spots I have
seen on occasion. Tended more toward a brownish
color with darker brown/black spots. That glaze was
also layered several times to get that effect. Where I
layered it four or more times I got a hare's fur looking
result, rather than oil spot.
I took some of each of these to NCECA/Clayart room,
and folks saw them there. But - I don't have any pics
of them, they were just glaze tests on small cups. I
don't use oil spots right now - I was just curious, and
interested in getting more depth at cone 6.
Pete Pinnell had an article(s) some time back in Clay Times,
on changing melt points of glazes. Very useful.
I have no doubt that most of the folks who asked re:
oil spots at cone 6 know a good deal more about oil
spot glazes than I do.
regards
Dannon Rhudy
Roger W. Cramer on fri 9 sep 05
Dannon:
Can you say some more about the process you used to transition from ^9 to
^6, what materials you used to lower the temperature on the Harding Black
glazes and with what formulas you finally ended up? Thanks in advance for
your response and for opening up what appeared to be a closed issue with
Oil Spot glazes for those of us working at ^6. Roger
Roger W. Cramer
50 Marlboro Street
Newburyport, MA 01950
www.cramerpottery.com
Steve Slatin on fri 9 sep 05
Earl --
To get an oil spot glaze with thermal reduction of
iron does seem to require ^9 or above -- at least John
Britt makes a convincing case for it, and he's tested
the issue to a fare-the-well. But the effect isn't
necessarily the result of iron. Dannon, what's in
that ^6 glaze you're using? Cobalt, maybe?
-- Steve S
--- Earl Krueger wrote:
> On Thu, 2005-09-08 at 12:02 -0500, dannon rhudy
> wrote:
> > I have made many oil-spot glazes at cone 6,
>
> Whaaaaat ???
>
> Everything I've read says that you need to reach a
> temperature about
> cone 9 in order for the iron oxide to auto-reduce,
> which is what
> produces the oil spots.
Steve Slatin --
Drove downtown in the rain
9:30 on a Tuesday night
Just to check out the
Late night record shop
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Jorge Nabel on sat 10 sep 05
Dear Earl, you made the right question for me to jump on this topic.
I work on earthenware, cone 05. And I work with comercial glazes.
Maybe I cannot call what I did Oil spot, but if you see some pieces
I made you wouldnt believe they are so low temperature.
I worked with an iron saturate glaze, about 10% RIO ,on a gas kiln,
oxidized till cone 05 bends, then a 15 minutes hold on reduction,
and then a 2 hours soak at 950ºC in oxidation.
I was really shocked with the results.And also very happy.
You can see a detail on http://www.jorgenabel.com/detalles1.html
Good luck with your experiments.
Jorge en Buenos Aires
"Everything I've read says that you need to reach a temperature about
cone 9 in order for the iron oxide to auto-reduce, which is what
produces the oil spots.
Is this not true ??"
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