Pat Colyar on fri 17 nov 06
OK, Donna, give us a hint here; what cone? Oxidation or reduction?
crabby Pat the ceramics tech, in wet gold Bar, WA
Donna Kat on fri 17 nov 06
We will not get an order in for some time and I would like to try to come
up with a satin opaque yellow - less yellow than sunshine but darker than
cold butter. No brown, green or orange hues. It definitely needs to be
in the yellow family and not cream white but soft and not garrish. I've
done a search but I keep coming up with stains which we don't have. I was
told that yellow ochre would work but it needs another ingredient which
the person did not remember. Anyone know what that might be?
Donna
Ivor and Olive Lewis on sat 18 nov 06
Dear Donna Kat ,
There are four basic compounds that will give some form of yellow; =
Vanadium Pentoxide, Antimony Oxide, Manganese Dioxide (or Carbonate) and =
Praseodymium Oxide. The last gives the brightest purest spectrum yellow. =
See Frank Hamer's Dictionary for all the information.
I have never succeeded in getting a yellow or yellow orange form Iron =
oxides or Yellow ochre.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Donna Kat on sat 18 nov 06
On Sat, 18 Nov 2006 11:04:09 +1000, John Dellow
wrote:
>Donna Kat wrote:
>> We will not get an order in for some time and I would like to try to
come
>> up with a satin opaque yellow - less yellow than sunshine but darker
than
>> cold butter. No brown, green or orange hues. It definitely needs to be
>> in the yellow family and not cream white but soft and not garrish. I've
>> done a search but I keep coming up with stains which we don't have. I
was
>> told that yellow ochre would work but it needs another ingredient which
>> the person did not remember. Anyone know what that might be?
>>
>> Donna
>>
>>
>>
>Donna ,
> look up Woo Yellow in the archives. I did an ian currie 25 step test
>using that recepie and came up with some nice yellows. Its a rutile C10
>glaze. I can send you a scan of the tile . Its on an iron clay
>
>--
>
> John Dellow "the flower pot man"
Thank you, looked it up and am left wondering "why is this a cone 10 glaze
with that much Barium?" Is it because it has so little Flint that it is a
matt and cone 10?
I do oxidation (should have mentioned that - sorry) and cone 6. I imagine
I could turn this into a cone6 rather easily just by making it a stable
glaze but given that the poster mentions that substituting out the barium
with strontium carbonate doesn't give the same coloring I suspect I can't
make this work. By the by, I keep getting conflicting information on
barium being a toxic material. Does anyone know the latest on this?
Glaze name: Woo Yellow
Cone: 9 - 10
Color: Yellow Opaque
Testing: Tested
Surface texture: Stoney Matt
Firing: Reduction
Glaze type: Ba Ca Mg
Recipe: Percent Batch
Kona F-4 Spar 39.29 1964
Barium Carbonate 29.76 1488
Dolomite 14.29 714
EPK 8.33 417
Flint 8.33 417
Totals: 100.00 % 5000 Gm
Also add:
Zircopax 17.86 893
Red Iron Oxide 3.57 178
Comments:
Originally from Clarence Merritt to Gene Lewis - was named Lewis
Yellow. Current recipe from Val Cushing.
Possible Health Hazards:
Barium Carbonate: HIGHLY Toxic-avoid ingestion. Do not use in glazes
intended for use with food.
Maurice Weitman on sat 18 nov 06
At 13:43 -0500 on 11/18/06, Donna Kat wrote:
>Thank you, looked it up and am left wondering "why is this a cone 10 glaze
Hello, Donna,
There are several (many) "woo yellow" glaze references, recipes, and
tests mentioned in the archives, including many for cone 6.
>By the by, I keep getting conflicting information on
>barium being a toxic material. Does anyone know the latest on this?
Where've you been, Donna? There must have been 100 messages about
Barium in early November. Many authoritatively state out how
terribly poisonous or absolutely safe barium is. I'm sure you can
find an answer from which to choose as your very own "latest."
And that's the latest conflicting information from clayart.
Regards,
Maurice
Timothy Joko-Veltman on sat 18 nov 06
On 11/18/06, Donna Kat wrote:
> I do oxidation (should have mentioned that - sorry) and cone 6. I imagine
> I could turn this into a cone6 rather easily just by making it a stable
> glaze but given that the poster mentions that substituting out the barium
> with strontium carbonate doesn't give the same coloring I suspect I can't
> make this work. By the by, I keep getting conflicting information on
> barium being a toxic material. Does anyone know the latest on this?
Barium carbonate (what most potters use) is highly toxic, and is even
used as rat posion. Barium sulfate (the stuff they make you drink in
the hospital to see your innards better) is non-toxic. The barium in
a fired glaze, barium oxide, leaches quite easily, and is toxic,
especially in combination with acids (think lemons and stomach
juices).
If you use glazes with barium carbonate in them, I (and many others
here) would strongly recommend that you not use them on food surfaces
- unless you have had them thoroughly tested, and are sure they leach
practically no barium at all. I myself probably wouldn't even do it,
then ... .
Cheers,
Tim
Donna Kat on sat 18 nov 06
Yes, sorry about that - I know better, just not attending too well. I
thought but did not say, What oxides give yellow in a cone 6, oxidation
firing.
I'm not actually looking for a glaze since I want to use the bases that
we have. As I said, I thought that a small amount of iron or vanadium
might work. Someone mentioned that there is another ingredient that works
with iron to help develop a yellow color but that iron by itself did not
work for her. She was not sure how it was spelled or how to pronounce it
but as she said it, it sounded like one of the rare earth elements. I'm
waiting for her to get back to me on the ingredient she used - being
impatient I thought I would ask.
I have been given 2 glazes which look very promising.
Donna
P.S. I may have opened a hornet's nest when I asked about Barium
(something I never use so I've never investigated until now when one of
the glazes I found used it and I knew that it does impact on the color).
I had read somewhere that people mistakenly think of barium as being
dangerous because of it being radioactive and that this was not true for
what is used in ceramics. After rightly being chastized I went hunting
and this is I think one of the better and easy to read sites on what is a
health hazard in this business.
http://web.princeton.edu/sites/ehs/artsafety/sec12.htm#g
John Dellow on sat 18 nov 06
Donna Kat wrote:
> We will not get an order in for some time and I would like to try to come
> up with a satin opaque yellow - less yellow than sunshine but darker than
> cold butter. No brown, green or orange hues. It definitely needs to be
> in the yellow family and not cream white but soft and not garrish. I've
> done a search but I keep coming up with stains which we don't have. I was
> told that yellow ochre would work but it needs another ingredient which
> the person did not remember. Anyone know what that might be?
>
> Donna
>
>
>
Donna ,
look up Woo Yellow in the archives. I did an ian currie 25 step test
using that recepie and came up with some nice yellows. Its a rutile C10
glaze. I can send you a scan of the tile . Its on an iron clay
--
John Dellow "the flower pot man"
From the land down under
Home Page http://www.welcome.to/jkdellow
http://digitalfire.com/education/people/dellow/
Paul Herman on sun 19 nov 06
Greetings Ivor, and John,
Recently we've been getting yellow colors from iron glazes in the
salt chamber. A dark iron glaze like "Sechrest black" will flash
yellow in light salt, and get honey colored and runny in heavy salt.
Now comes the question, can either of you shed some light on why the
salt helps the yellow develop? To me it looks like some kind of iron
crystals growing in the glaze. Albany slip, when fired in the
anagama, gets yellow flashes from ash.
Inquiring minds need to know.
Best,
Paul Herman
Great Basin Pottery
Doyle, California US
http://greatbasinpottery.com
On Nov 19, 2006, at 7:19 PM, John Britt wrote:
> Ivor,
>
> You can get great yellows from iron oxide:
>
Liisa Reid on sun 19 nov 06
You may be thinking of praeseodymium. It is available as a mason
stain.
Liisa
On Nov 18, 2006, at 6:38 PM, Donna Kat wrote:
> Yes, sorry about that - I know better, just not attending too well. I
> thought but did not say, What oxides give yellow in a cone 6,
> oxidation
> firing.
>
> I'm not actually looking for a glaze since I want to use the
> bases that
> we have. As I said, I thought that a small amount of iron or vanadium
> might work. Someone mentioned that there is another ingredient
> that works
> with iron to help develop a yellow color but that iron by itself
> did not
> work for her. She was not sure how it was spelled or how to
> pronounce it
> but as she said it, it sounded like one of the rare earth
> elements. I'm
> waiting for her to get back to me on the ingredient she used - being
> impatient I thought I would ask.
>
> I have been given 2 glazes which look very promising.
> Donna
>
> P.S. I may have opened a hornet's nest when I asked about Barium
> (something I never use so I've never investigated until now when
> one of
> the glazes I found used it and I knew that it does impact on the
> color).
> I had read somewhere that people mistakenly think of barium as being
> dangerous because of it being radioactive and that this was not
> true for
> what is used in ceramics. After rightly being chastized I went
> hunting
> and this is I think one of the better and easy to read sites on
> what is a
> health hazard in this business.
>
> http://web.princeton.edu/sites/ehs/artsafety/sec12.htm#g
>
> ______________________________________________________________________
> ________
> 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.
John Dellow on sun 19 nov 06
Donna Kat wrote:
>
>
> Thank you, looked it up and am left wondering "why is this a cone 10 glaze
> with that much Barium?" Is it because it has so little Flint that it is a
> matt and cone 10?
>
>I do not know why,I am not the originator of this glaze. The barium does
not bother me as I was only going to use it on the outside of mugs below
the lipline.
John
John Dellow "the flower pot man"
From the land down under
Home Page http://www.welcome.to/jkdellow
http://digitalfire.com/education/people/dellow/
Timothy Joko-Veltman on sun 19 nov 06
On 11/18/06, Donna Kat wrote:
> I'm not actually looking for a glaze since I want to use the bases that
> we have. As I said, I thought that a small amount of iron or vanadium
> might work. Someone mentioned that there is another ingredient that works
> with iron to help develop a yellow color but that iron by itself did not
> work for her. She was not sure how it was spelled or how to pronounce it
> but as she said it, it sounded like one of the rare earth elements. I'm
> waiting for her to get back to me on the ingredient she used - being
> impatient I thought I would ask.
She's probably talking about praseodymium (I don't know how to
pronounce this properly either) ... a "rare earth" or "lanthanide".
You can read more about using it as a colourant in ceramic glazes
here: http://www.ceramicstoday.com/articles/lanthanides.htm, and here:
http://www.lagunaclay.com/news/rare.htm
Cheers,
Tim
Bonita Cohn on sun 19 nov 06
I get a nice ash glaze at cone 10 using yellow ochre...
2% give or take...
Its a softer yellow - kinda "chicken fat" yellow!!
Bonita in San Francisco.
Bonita Cohn
http://www.bonitacohn.com
---------------------------------
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John Britt on sun 19 nov 06
Ivor,
You can get great yellows from iron oxide:
http://www.johnbrittpottery.com/images/IMAGE77.jpg
I have a whole chapter on yellows in my book.
Also, if you get the 5th edition of Hamer and Hamer you will see she/he
lists iron "when bleached in a lime matt glaze" (i.e. ash glazes) gives
yellows.
John Britt
www.johnbrittpottery.com
Des & Jan Howard on mon 20 nov 06
John
Cardew in "Pioneer Pottery" gives a recipe for a calcium/iron yellow.
A version I have used is:
Kaolin 55
Limestone 26.25
Silica 18.75
Red iron oxide 4
Thin dip, Cone 8-9 reduction.
Matt mustard rather buttercup.
Magnesium satin glazes with small amount of iron
under can give yellow crystals. An example of this effect
on p.78 of Ian Currie's "Revealing Glazes".
Des
John Britt wrote:
>Ivor,
>
>You can get great yellows from iron oxide:
>
>http://www.johnbrittpottery.com/images/IMAGE77.jpg
>
>I have a whole chapter on yellows in my book.
>
>Also, if you get the 5th edition of Hamer and Hamer you will see she/he
>lists iron "when bleached in a lime matt glaze" (i.e. ash glazes) gives
>yellows.
>
>
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
Ivor and Olive Lewis on mon 20 nov 06
Dear John,
Thank you for that image. I appreciate you help.
Sorry, but if you class that as yellow there is something wrong with
my eyes for it does not match the Lemon nor the Banana I used for
comparison. Nor does it match the Praseodymium Yellow Stain from Mason
that I use when I require that colour for my work. Would I find
anything like that in the spectrum of sunlight ?.
If I were to describe it I would suggest that it is a traditional
treacle hue.
Had I to imitate it or reproduce it in paint I would start with
Cadmium Orange, then as necessary, reduce the chromatic intensity with
Cobalt Blue, adjust the tonality with titanium white and Burnt Umber
in varying proportions.
I have a strong opinion that there is a need in art instruction to
provide a rationale for the analysis of Hue. In the past the teaching
of Frank Covino has given me a secure foundation in colour appraisal.
His precise way of thinking about Colour is a model worth considering.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
----- Original Message -----
From: "John Britt"
To: ; "Ivor Lewis"
Sent: Monday, 20 November 2006 1:49
Subject: Re: oxides for yellow - not using stains
> Ivor,
>
> You can get great yellows from iron oxide:
>
> http://www.johnbrittpottery.com/images/IMAGE77.jpg
>
> I have a whole chapter on yellows in my book.
>
> Also, if you get the 5th edition of Hamer and Hamer you will see
she/he
> lists iron "when bleached in a lime matt glaze" (i.e. ash glazes)
gives
> yellows.
>
>
> John Britt
> www.johnbrittpottery.com
Donna Kat on tue 21 nov 06
>She's probably talking about praseodymium (I don't know how to
>pronounce this properly either) ... a "rare earth" or "lanthanide".
>You can read more about using it as a colourant in ceramic glazes
>here: http://www.ceramicstoday.com/articles/lanthanides.htm, and here:
>http://www.lagunaclay.com/news/rare.htm
>
>Cheers,
>
>Tim
Yes, that is what it was (I got email tonight). Given that this is an
oxidation firing, that the glaze wanted is an opaque, satin matt.... I'm
guessing this is going to be an interesting adventure.
I have enjoyed the thread and as always have learned something new from
many helpful people.
Thank you all,
Donna
Ivor and Olive Lewis on wed 22 nov 06
Dear Paul Herman,=20
Somewhere along the thread I seem to have inferred it was impossible to =
obtain Yellow from glazes that were tinted with Iron Oxide and I am =
catching a lot of flak over that. All I recall doing is suggesting =
Praseodymium oxide, Vanadium Pentoxide or Antimony oxide. Must say I =
forgot that I have a slate glaze that throws out wonderful yellow =
crystals that seem to derive from Titanium minerals that the slate =
contains. Rutile is another minerals which in glazes will, with =
fractions of Iron oxide, provoke yellow rather than deep brown (Burnt =
Umber) or olive green hues.
Much of what happens in a Salt Glaze Kiln remains mysterious, =
inexplicable, unpredictable. People often speak of "Bleaching", no doubt =
encouraged by our familiarity with Chlorine as bleaching agent. Research =
done by the British Ceramic Research association mid 20 th Century into =
the nature of Salt Glaze Kiln effluent showed that many elements were =
extracted from parent clay and collected as chloride salts. Iron was one =
of these as was Aluminium. Unbelievably, because of the insistence of =
those who speculate about reactions between Salt and Clay and tell us =
there is a reaction between Sodium Oxide and Silica, Silicon Chloride =
was found in effluent gases
Your observations tell me very little. They are in some ways anomalous =
when related to popular dogma about the behaviour of Iron oxides, in =
that they enhance the fluidity of a melt ( I believe Iron oxides are =
regarded as strong fluxing agents at high temperatures). If Iron oxide =
is being removed from a glaze the expectation could be that it would =
stiffen rather than flow more freely.
Searching lists of Iron Compounds seems to indicate Iron Chromate as the =
only yellow crystalline compound that could exist as a residue in a =
glaze. FeO and Fe3O4 are Black. Fe2O3 is red. Other yellow Iron =
compounds are associated with degrees of Hydration or of Iron combined =
with Carbon Monoxide.
Perhaps John has a solution.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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