Chris Schafale on sat 23 jan 99
Greetings, all.
I have a couple of questions about rutile. First, I recently got a
new batch of rutile. My first batch was labelled just Rutile,
Powdered. My new batch is labelled Rutile, Powdered, Light. I put
some of the new rutile in a new batch of a glaze I had used before,
that was supposed to be a deep cobalt blue. It came out a much
lighter, medium blue instead. My question is, does the light rutile
make that much difference, or does it sound more like I mis-measured?
I know the difference was not due to firing conditions because I had
some of the old glaze in the same kiln load, and it was the familiar
deep vibrant blue.
If the light rutile does make that much difference, is there
anything I can do at this point to rescue this bucket of glaze? The
new color is nice, but it's not what I was aiming for. Would it help
to add more cobalt? Or perhaps a little bit of iron, since the new
rutile may be purer than the old?
Second question: When I mentioned this problem to another local
potter, she said she had heard that there had been a change in the
rutile that is being supplied to ceramic supply houses, and that it
now is a purer form, which gives a different color response. This
was a problem for some potters who had developed lines of work using
the old rutile in their glazes. Has anyone else heard about this
change or know whether it is true??
Thanks for any help.
Chris
Light One Candle Pottery
Fuquay-Varina, NC
candle@nuteknet.com
Marty Anderson on mon 25 jan 99
Hi Chris,
You seem to use a lot of rutile, do you know of a source to get Dark Rutile?
It has a high iron content.
thanks
marty
martya@airmail.net
-----Original Message-----
From: Chris Schafale
To: CLAYART@LSV.UKY.EDU
Date: Saturday, January 23, 1999 5:14 PM
Subject: Rutile questions
----------------------------Original message----------------------------
Greetings, all.
I have a couple of questions about rutile. First, I recently got a
new batch of rutile. My first batch was labelled just Rutile,
Powdered. My new batch is labelled Rutile, Powdered, Light. I put
some of the new rutile in a new batch of a glaze I had used before,
that was supposed to be a deep cobalt blue. It came out a much
lighter, medium blue instead. My question is, does the light rutile
make that much difference, or does it sound more like I mis-measured?
I know the difference was not due to firing conditions because I had
some of the old glaze in the same kiln load, and it was the familiar
deep vibrant blue.
If the light rutile does make that much difference, is there
anything I can do at this point to rescue this bucket of glaze? The
new color is nice, but it's not what I was aiming for. Would it help
to add more cobalt? Or perhaps a little bit of iron, since the new
rutile may be purer than the old?
Second question: When I mentioned this problem to another local
potter, she said she had heard that there had been a change in the
rutile that is being supplied to ceramic supply houses, and that it
now is a purer form, which gives a different color response. This
was a problem for some potters who had developed lines of work using
the old rutile in their glazes. Has anyone else heard about this
change or know whether it is true??
Thanks for any help.
Chris
Light One Candle Pottery
Fuquay-Varina, NC
candle@nuteknet.com
Tom Buck on mon 25 jan 99
Chris:
Your rutile, powdered, light, is still 92% Titanium IV oxide
("dioxide"). What is different is the particle size, the light coloured
powder has very small particles, less than 44 microns (44 micro-metres,
44x10^-6 metres). As a result, the titanium oxide (with its FeO intact)
will more readily blend into the glass matrix, and not be as much of an
adjunct colouring agent as are the bigger regular-grade rutile particles.
You could add some Iron Oxide Black (if you have it), approx one
tenth of the weight of light rutile used, and see if you achieve the
deeper blue colour. In some glaze mixes, eg, Penland Purple, iron oxide
alone will yield a blue colour if the glaze is applied thickly (the colour
comes from the wavelength of light transmitted by / reflected from the
iron silicate, see Cardew, Pioneer Pottery p 140.
Most dealers once sold both rutile coarse and rutile ceramic-grade
(powder, light) and labelled them as such. The trend in the
ilmenite/rutile/zircon operations in Australia, major supplier to
N.America, is to do more processing of the ore to upgrade the products. So
Ozland now ships rutile ceramic grade in amounts that allow the ceramic
market to be served. Where once USA/Canada titanium operations were fed
with raw ilmenite, now they receive both ilmenite (as an upgraded
concentrate) and titanium slag,. The latter, titanium slag, is becoming
the preferred feed to titanium plants, and if they begin with the slag
they no longer isolate rutile during the processing. So scratch one old
source of rutile coarse, and get used to the ultra-fine powder.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
Louis Katz on mon 25 jan 99
In my experience rutile is the single biggest variable in glazes. Buy a
fifty pound bag, bite the bullet. Anytime you order rutile you could be
getting a slightly different material. More posts on clayart have been
made about variation in rutile than any other material. The same variations
occur in other titanium minerals including titanium dioxide produced for
paint pigments.
Louis
> ----------------------------Original message----------------------------
> Greetings, all.
>
> I have a couple of questions about rutile. First, I recently got a
> new batch of rutile. My first batch was labelled just Rutile,
> Powdered. My new batch is labelled Rutile, Powdered, Light. I put
> some of the new rutile in a new batch of a glaze I had used before,
> that was supposed to be a deep cobalt blue. It came out a much
> lighter, medium blue instead. My question is, does the light rutile
> make that much difference, or does it sound more like I mis-measured?
>
> I know the difference was not due to firing conditions because I had
> some of the old glaze in the same kiln load, and it was the familiar
> deep vibrant blue.
>
> If the light rutile does make that much difference, is there
> anything I can do at this point to rescue this bucket of glaze? The
> new color is nice, but it's not what I was aiming for. Would it help
> to add more cobalt? Or perhaps a little bit of iron, since the new
> rutile may be purer than the old?
>
> Second question: When I mentioned this problem to another local
> potter, she said she had heard that there had been a change in the
> rutile that is being supplied to ceramic supply houses, and that it
> now is a purer form, which gives a different color response. This
> was a problem for some potters who had developed lines of work using
> the old rutile in their glazes. Has anyone else heard about this
> change or know whether it is true??
>
> Thanks for any help.
>
> Chris
> Light One Candle Pottery
> Fuquay-Varina, NC
> candle@nuteknet.com
--
Louis Katz
lkatz@falcon.tamucc.edu
NCECA Director At Large
Texas A&M-CC Division of Visual and Performing Arts Webmaster (512)
994-5987
Visit the NCECA World Ceramics Image Database
Richard Aerni on mon 25 jan 99
Marty,
When I was doing my rutile testing and obtained samples from suppliers
all around the country, the darkest by far was from Westerwald Ceramic
Supply in Pittsburgh. Of course this was in 1997, but you may want to
give them a call (they advertise in CM).
Good luck,
Richard Aerni
Marty Anderson wrote:
>
> ----------------------------Original message----------------------------
> Hi Chris,
>
> You seem to use a lot of rutile, do you know of a source to get Dark Rutile?
> It has a high iron content.
>
William Emley on mon 25 jan 99
HOWDY:
in my ceramic tile buisness we make a low fire bone glaze that uses what
seems to be refered to as light rutile. We were accidently sent some rutile
simply labled rutile which when used turned our normally light bone glaze into
an opaque toffee color. As far as I know ther is no way to correct a batch of
glaze that has had these rutiles switched although you might try to add .05 %
iron ox to compensate for the light rutile.
Bruce Girrell on sun 20 feb 05
Greetings, oh wisened ones -
When a glaze recipe calls for rutile or ilmenite and doesn't specify the
form, would you normally assume that the powdered form or the granular form
is being called for?
Our experience with the granular form is that it simply doesn't melt. It
stays as little black specks in the glaze, despite the fact that we often go
to cone 11 or 12. Is there another substance that acts particularly well as
a flux for rutile/ilmenite granules? When Lynne was first taking pottery
classes at a local college she used one of their ilmenite glazes that
produced tan/gold spots on a white background. Despite the fact that we have
the college's recipe we have been unable to reproduce the effect. Powdered
ilmenite colors the whole glaze and granular ilmenite results in little
black specks. What might we be missing?
Bruce "less than wisened today" Girrell
David Hendley on sun 20 feb 05
----- Original Message -----
> When a glaze recipe calls for rutile or ilmenite and doesn't specify the
> form, would you normally assume that the powdered form or the granular
form
> is being called for?
"Rutile" in a recipe means powdered rutile.
Although I've not run across a recipe that calls for simply "illmenite", I
would
assume it is calling for granular illmenite, the much, much more common form
of illmenite. I don't even know of any suppliers that stock powdered
illmenite.
>
> Our experience with the granular form is that it simply doesn't melt. It
> stays as little black specks in the glaze, despite the fact that we often
go
> to cone 11 or 12. Is there another substance that acts particularly well
as
> a flux for rutile/ilmenite granules?
If tan/gold spots is what you're after, you want granular illmentite. If
your
illmenite is not melting enough, maybe you need to use it in a glaze base
with more flux. The notorious "Moonlight", the most well-known spotted
illmenite glaze, is runny at cone 10+. It calls for both rutile and
illmentite
and it is also a finicky glaze, on a par with Floating Blue and copper reds.
David Hendley
Working hard to make sure there is no mug left behind
david@farmpots.com
http://www.farmpots.com
Edouard Bastarache Inc. on mon 21 feb 05
Hello David,
I have 2 types of powdered Ilmenite, one bought years ago from
a supplier and one from a company extracting and processing it,
in our region.
The one coming from the local company is very fine because
it comes from the anti-pollution system of a department called
"Enrichment Plant".
Later,
"Ils sont fous ces quebecois"
"They are insane these quebekers"
"Están locos estos quebequeses"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
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