Karl P. Platt on mon 14 apr 97
I just wanted to mention that I gave an exhaustive treatment to making
of Ti (rutile, as it were) blue glazes some time back. This article may
be read by following the magic link below:
http://apple.sdsu.edu/ceramicsweb/articles/tech_handouts/titania_in_glaze.html
Rutile is a highly fugitive material -- I don't care what any sales rep
has to say about it -- *always test the Rutile* before commiting to
production. The article above suggests options to correct difficulties.
Regards,
Karl P. Platt
27 degress south -- where it's autumn and the sunsets are *gasp*
Lili Krakowski on thu 5 feb 98
I have not fired glazes in gas reduction in so long I am not sure I am
even in the ballpark here. But as I seem to recall rutile blue in a gas
kiln is achieved by reduction. i.e. rutile in reduction = blue. For blue
in an electric kiln, to the best of my admitedly-limited knowledge, one
needs a. rutile. b. cobalt. And there a great many glazes will do nicely.
I'd suggest you try several; a zinc containing glaze, a
calcium borate glaze, one that contains tin as well, and do blends.
Lili Krakowski
Tom Wirt on fri 6 feb 98
We use Conrads Moonlight (which was discussed about 6 months ago here)
with about 1/2%cobalt Carb. added. It's a cone 10 glaze. I first
started using it in electric firing, and a year ago switched to gas. At
first in the gas, it was muddier and tended toward rutile blue-green.
Then, experimenting, we cooled the kiln faster to match the curve of the
electrics. Voila, nice sharp crystals and blue. It also seems to be
quite sensitive to temperature, over fire it and it grabs iron from
anywhere and goes blue green or brownish.
I also might note that it is quite sensitive to application. It must go
on thick to develop a good blue. (even sometimes giving almost purple).
Thick in the bucket, double dip as soon as the sheen leaves, dry
completely, then rub lightly everywhere and especially on compund curves.
This is a Cornwall recipe and tends to crawl if not thorughly bonded to
the clay surface. The thickness required doesn't help.
Don't know what it might do at c6 but if you get there, the above notes
might help.
Tom Wirt
Clay Coyote Pottery
Hutchinson, MN
claypot@hutchtel.net
The Slack-DeBrock Family on sat 7 feb 98
Tom- could you share the recipe for Conrad's Blue that you spoke about?
Thanks.
Joan slack-deBrock
riverrun@newnorth.net
Laura Conley on sun 8 feb 98
Could silicon carbide be used for local reduction of rutile in an oxidizing
environment, as it is used for copper?
Laura Conley
Boulder, CO
Lili Krakowski wrote:
> ----------------------------Original message----------------------------
>
> I have not fired glazes in gas reduction in so long I am not sure I am
> even in the ballpark here. But as I seem to recall rutile blue in a gas
> kiln is achieved by reduction. i.e. rutile in reduction = blue. For blue
> in an electric kiln, to the best of my admitedly-limited knowledge, one
> needs a. rutile. b. cobalt. And there a great many glazes will do nicely.
> I'd suggest you try several; a zinc containing glaze, a
> calcium borate glaze, one that contains tin as well, and do blends.
> Lili Krakowski
Tom Wirt on mon 9 feb 98
> Joyce brought up a good pointThe rutile blue Moonlight from Conrad (G375) is r
understand, most rutile blues are.
The way we work around this is to provide a ridge at the foot and, when
Betsy applies the glaze, she takes a stainless rib and carves a taper
into the ridge. Sounds timeconsuming, and is, but it goes pretty fast
after you've done a few. The main time we lose pieces from running now
is where there's an overlap with another glaze, especially Temmoku. But
by keeping it high on the pot, it can be controlled.
Tom Wirt
Lili Krakowski on tue 10 feb 98
I have no idea. I ahve done very little silicon carbide local reduction,
and I do not think I ever saw any suggestions for local reduction except
for copper--i.e. to get copper reds. But there's nothing to prevent your
trying, and God willing, there will be this great wonderful thrilling
Laura Conley Rutile Blue Local Reduction glaze out there.
Lili Krakowski
Michelle H. Lowe on tue 10 feb 98
>Lili Krakowski wrote:
>
>> ----------------------------Original message----------------------------
>>
>> I have not fired glazes in gas reduction in so long I am not sure I am
>> even in the ballpark here. But as I seem to recall rutile blue in a gas
>> kiln is achieved by reduction. i.e. rutile in reduction = blue. For blue
>> in an electric kiln, to the best of my admitedly-limited knowledge, one
>> needs a. rutile. b. cobalt. And there a great many glazes will do nicely.
>> I'd suggest you try several; a zinc containing glaze, a
>> calcium borate glaze, one that contains tin as well, and do blends.
>> Lili Krakowski
I fired cone 6 oxidation pretty exclusively for five years and worked with
many glazes (being a glaze testing maniac). One that I really enjoyed
using, for several years (and I still use it occasionally) was a Rutile
Pale Blue that has no cobalt in it, yet goes most definitely blue in
oxidation. It is a tan mat if it isn't fired high enough and glossy pale
translucent blue (almost celadon-like) at temp. Usually crazes...
Here's the recipe I have-
Pale Rutile Blue cone 6 ox
Gerstley Borate 8.45
Mag Carb 1.86
Whiting 15.30
Wood Ash 14.54
Neph Sy 15.55
Kaolin 10.91
Flint 33.39
Total 100.00
Add:
Rutile 1.69
Mishy, enjoying an unusually cold and rainy Sonoran desert
Michelle Lowe, potter in the Phoenix desert \|/ |
mishlowe@indirect.com -O- | |
mishlowe@aztec.asu.edu /|\ | | |
|_|_|
____ |
http://www.amug.org/~mishlowe -\ /-----|-----
( )
<__>
Tom Wirt on tue 10 feb 98
Hi, This is a compilation of several background messages re: the Conrad
Moonlight.
We use Conrads Moonlight (which was discussed about 6 months ago here)
with about 1/2%cobalt Carb. added. It's a cone 10 glaze. I first
started using it in electric firing, and a year ago switched to gas. At
first in the gas, it was muddier and tended toward rutile blue-green.
Then, experimenting, we cooled the kiln faster to match the curve of the
electrics. Voila, nice sharp crystals and blue. It also seems to be
quite sensitive to temperature, over fire it and it grabs iron from
anywhere and goes blue green or brownish.
I also might note that it is quite sensitive to application. It must go
on thick to develop a good blue. (even sometimes giving almost purple).
Thick in the bucket, double dip as soon as the sheen leaves, dry
completely, then rub lightly everywhere and especially on compund curves.
This is a Cornwall recipe and tends to crawl if not thorughly bonded to
the clay surface. The thickness required doesn't help.
Don't know what it might do at c6 but if you can get it there, the above
notes might help.
One note, I mentioned that it's sensitive to temp. It's happiest
between 9-1/2 and 10-1/2. Also we use it on a white stoneware. On iron
body clays, it tends toward blue green or brown-green...not too pretty.
Conrad G375 Moonlight Blue
Cornwall Stone 63.8%
Gertsley Borate 14.3%
Silica (A-25 best) 7.6%
Whiting 7.6%
Edgar Plastic Kaolin 4.8%
Zinc Oxide 1.9%
Rutile (powdered) 3.2%
Ilmenite (325 mesh best) 2.0% (Mile Hi in Denver has it).
Cobalt Carbonate 0.5%
Likes a fast cooling to develop that electric blue. One dip gives you
brown, two dips a deep blue. Tends to break on ridges. Where real
heavy you get white. Flows quite a bit, especially combined with other
glazes. Watch your bottom feet,try to give it a good foot or a strong
ridge to stop flow. Tapering the bottom edge with a straight edge helps
too. Otherwise your shelf will be a beautiful shade of blue. If thick,
tends to pinhole, likes to dry and be rubbed out before firing.
Tempermental glaze---can crawl just enough to make you crazy generally
under rims and on the inside of rims....probably is thicker there and
shrinks when drying.
To Mix, we've found it best to dissolve the Cornwall first and let set a
bit, then add everything else. Screen through a 40 once and an 80mesh
twice for finest crystalization.
> Joyce brought up a good pointThe rutile blue Moonlight from Conrad (G375) is r
understand, most rutile blues are.
The way we work around this is to provide a ridge at the foot and, when
Betsy applies the glaze, she takes a stainless rib and carves a taper
into the ridge. Sounds time consuming, and is, but it goes pretty fast
after you've done (not had) a few. The main time we lose pieces from
running now is where there's an overlap with another glaze, especially
Temmoku. But by keeping it high on the pot, it can be controlled.
Good Luck. It can be a fantastic rutile blue, best I've seen.
I'll be off the list for a week, at Rosen, but will pull digests during
the week.
Tom Wirt
Clay Coyote Pottery
Hutchinson, MN
claypot@hutchtel.net
Joyce Lee on thu 24 sep 98
Hi Peter,
Are you starting down an interesting and frustrating road! I've had the
tan, the blue, the lavender, the cream, the yellow, and a temoku-like
brown from my one bucket of rutile. Most ran. Am giving up...for now.
When I did get the blue it was stunning and kept me trying just one more
time.. One informed Clayarter (either Craig, Bill, Tony H., Ron, Tom W.
or ?, I think) told me that sometimes the rutile goes to the sides of
the bucket and might need, not only fresh mixing, but a bit more rutile
added from time to time. (I'm becoming accustomed to potters' terms like
"a bit," "occasionally," "enough". Such a contradiction to the precise
physical properties applied to firing and chemistry in measuring glazes.
Part of the charm, eh?)
Joyce
In the Mojave reading posts missed in August and tickled to dicover that
my young friend from the Mojave, Shauna, and HER Support Person, Rick,
are headed for Rick's home state of New York and eventually Alfred.
She's such a potter! We made a video of her teaching me to throw very
large platters. When I first met her she'd never heard of either Alfred
or Clayart. She began corresponding with Karen Gringhuis and met Richard
Aerni. Her direction changed from music and painting to ceramics.
Incredible.
terryh on sat 26 sep 98
------------------
i don't know the original thread of =22rutile blue=22. discussion.
here is how i like rutile blue.
on the clay i use w/ bit of iron, i always get blue w/ rutile blue glaze.
when it's thin, it is whitish:
so, when it breaks over a ridge texture, it creates blue-white split.
if applied over TC white, it creates tan-to-purple modulation.
if applied over Temmoku or Oil Spot Black, it creates real deep and
warm blue, very nice. the blue is different whether it's over temmoku
or oil spot.
if applied over ....., try by yourself. it's fun.
warning: it runs very well, especially over other glazes.
terry hagiwara
e-mail: terry.hagiwara=40halliburton.com (W)=3B terryh=40pdq.net (H)
web: http://www.geocities.com/SoHo/Cafe/3755
Evan Dresel on mon 28 sep 98
This was sent quite a while ago by Karl Platt, who sadly has been silent
recently. Don't know if the link is still good because my comm program is
messed up and I'm avoiding dealing with it until I get a new computer.
-- Evan in W. Richland WA who had a glaze start to craze right out of the
kiln even though it previously passed a freeze-boil test on the same body. Hmm.
At 09:53 AM 4-14-97 EDT, you wrote:
>----------------------------Original message----------------------------
>I just wanted to mention that I gave an exhaustive treatment to making
>of Ti (rutile, as it were) blue glazes some time back. This article may
>be read by following the magic link below:
>
>http://apple.sdsu.edu/ceramicsweb/articles/tech_handouts/titania_in_glaze.html
>
>Rutile is a highly fugitive material -- I don't care what any sales rep
>has to say about it -- *always test the Rutile* before commiting to
>production. The article above suggests options to correct difficulties.
>
>Regards,
>
>Karl P. Platt
>27 degress south -- where it's autumn and the sunsets are *gasp*
>
>
Jean Stephenson on tue 29 sep 98
The message I get says the file is not available or doesn't exist. Rats!
-----Original Message-----
From: Evan Dresel
To: CLAYART@LSV.UKY.EDU
Date: Monday, September 28, 1998 6:01 AM
Subject: Re: Rutile Blue
----------------------------Original message----------------------------
This was sent quite a while ago by Karl Platt, who sadly has been silent
recently. Don't know if the link is still good because my comm program is
messed up and I'm avoiding dealing with it until I get a new computer.
-- Evan in W. Richland WA who had a glaze start to craze right out of the
kiln even though it previously passed a freeze-boil test on the same body.
Hmm.
At 09:53 AM 4-14-97 EDT, you wrote:
>----------------------------Original message----------------------------
>I just wanted to mention that I gave an exhaustive treatment to making
>of Ti (rutile, as it were) blue glazes some time back. This article may
>be read by following the magic link below:
>
>http://apple.sdsu.edu/ceramicsweb/articles/tech_handouts/titania_in_glaze.h
tml
>
>Rutile is a highly fugitive material -- I don't care what any sales rep
>has to say about it -- *always test the Rutile* before commiting to
>production. The article above suggests options to correct difficulties.
>
>Regards,
>
>Karl P. Platt
>27 degress south -- where it's autumn and the sunsets are *gasp*
>
>
terryh on tue 29 sep 98
------------------
addendum: several asked me the recipe i'm using for the rutile blue.
my recipe is as follows:
Rutile Blue
Dolomite 158
Whiting 111
K-spar 300
EPK 168
Flint 263
---------------------------------
total 1000
Rutile 80
(needless to say, in practice, i use 160, 110, 300, 170, 260, and 80.)
terry
terry hagiwara
e-mail: terry.hagiwara=40halliburton.com (W)=3B terryh=40pdq.net (H)
web: http://www.geocities.com/SoHo/Cafe/3755
Michelle Lowe on wed 30 sep 98
At 09:17 AM 9/29/98 EDT, Jean Stephenson wrote:
>----------------------------Original message----------------------------
>The message I get says the file is not available or doesn't exist. Rats!
The article about Rutile (titania) in glazes still exists, you can see it
at this location now-
http://art.sdsu.edu/ceramicsweb/articles/tech_handouts/titania_in_glaze.html
Good luck :)
Mishy
>This was sent quite a while ago by Karl Platt, who sadly has been silent
>recently. Don't know if the link is still good because my comm program is
>messed up and I'm avoiding dealing with it until I get a new computer.
>
>-- Evan in W. Richland WA who had a glaze start to craze right out of the
>kiln even though it previously passed a freeze-boil test on the same body.
>Hmm.
>
>
>At 09:53 AM 4-14-97 EDT, you wrote:
>>----------------------------Original message----------------------------
>>I just wanted to mention that I gave an exhaustive treatment to making
>>of Ti (rutile, as it were) blue glazes some time back. This article may
>>be read by following the magic link below:
>>
>>http://apple.sdsu.edu/ceramicsweb/articles/tech_handouts/titania_in_glaze.h
>tml
>>
>>Rutile is a highly fugitive material -- I don't care what any sales rep
>>has to say about it -- *always test the Rutile* before commiting to
>>production. The article above suggests options to correct difficulties.
>>
>>Regards,
>>
>>Karl P. Platt
>>27 degress south -- where it's autumn and the sunsets are *gasp*
>>
>>
>
>
Michelle Lowe, potter in the Phoenix desert \|/ |
mishlowe@indirect.com -O- | |
mishlowe@aztec.asu.edu /|\ | | |
|_|_|
____ |
http://www.amug.org/~mishlowe -\ /-----|-----
( )
<__>
barbara lund on wed 30 sep 98
What cone is this please? Reduction or Oxidation?
At 09:18 AM 9/29/98 EDT, you wrote:
>----------------------------Original message----------------------------
>------------------
>addendum: several asked me the recipe i'm using for the rutile blue.
>my recipe is as follows:
>Rutile Blue
> Dolomite 158
> Whiting 111
> K-spar 300
> EPK 168
> Flint 263
>---------------------------------
> total 1000
> Rutile 80
>
>(needless to say, in practice, i use 160, 110, 300, 170, 260, and 80.)
>terry
>
>terry hagiwara
>e-mail: terry.hagiwara@halliburton.com (W); terryh@pdq.net (H)
>web: http://www.geocities.com/SoHo/Cafe/3755
>
Penny Hosler on thu 1 oct 98
Jean,
The "apple" part has changed.
http://art.sdsu.edu/ceramicsweb/
Then go to "Class Materials" and "Titania in Glazes"
Penny
-----Original Message-----
From: Jean Stephenson
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, September 29, 1998 6:17 AM
Subject: Re: Rutile Blue
>----------------------------Original message----------------------------
>The message I get says the file is not available or doesn't exist. Rats!
>-----Original Message-----
>From: Evan Dresel
>To: CLAYART@LSV.UKY.EDU
>Date: Monday, September 28, 1998 6:01 AM
>Subject: Re: Rutile Blue
>
>
>----------------------------Original message----------------------------
>This was sent quite a while ago by Karl Platt, who sadly has been silent
>recently. Don't know if the link is still good because my comm program is
>messed up and I'm avoiding dealing with it until I get a new computer.
>
>-- Evan in W. Richland WA who had a glaze start to craze right out of the
>kiln even though it previously passed a freeze-boil test on the same body.
>Hmm.
>
>
>At 09:53 AM 4-14-97 EDT, you wrote:
>>----------------------------Original message----------------------------
>>I just wanted to mention that I gave an exhaustive treatment to making
>>of Ti (rutile, as it were) blue glazes some time back. This article may
>>be read by following the magic link below:
>>
>>http://apple.sdsu.edu/ceramicsweb/articles/tech_handouts/titania_in_glaze.
h
>tml
>>
>>Rutile is a highly fugitive material -- I don't care what any sales rep
>>has to say about it -- *always test the Rutile* before commiting to
>>production. The article above suggests options to correct difficulties.
>>
>>Regards,
>>
>>Karl P. Platt
>>27 degress south -- where it's autumn and the sunsets are *gasp*
>>
>>
>
P.G.Hamer on fri 2 oct 98
Michelle Lowe wrote:
>
> The article about Rutile (titania) in glazes still exists, you can see it
> at this location now-
> http://art.sdsu.edu/ceramicsweb/articles/tech_handouts/titania_in_glaze.html
Can anybody expand on this paper, or provide additional references or
experiences?
I first heard about Ti3+ blues in an all too brief correspondence
with somebody (possibly Karl Platt, the author of this paper) a year
or so ago. This is the first thing I've seen since.
What, if any, is the relationship between Ti3+ blues and the well-
known, but imperfectly understood, Chun blues.
It is possible to get weakish Chun-type blues in glazes that do
not contain Ti. Is it possible to get Ti3+ effects in glazes that
do not show Chun-type properties such as opalescence?
Has anybody investigated Ti3+ and Chun blues spectrographically. The
popular "optical" explanation for Chuns would give a smooth spectra,
while Ti3+ should (presumably) give just a few spectral lines. What
is actually seen, and what fraction of the blue is caused by each
effect?
Why is the black-magic for Ti3+ blues and Chun blues so similar. Why
do both seem to suggest a base glaze supersaturated with a forign
type of glass.
Peter
BTW I don't know if there is one blue effect or two. Or which effect
actually occurs if only one does. At least some of the Chun literature
could easily be reinterpreted as a Ti3+ occuring in small drops of
foreign glass separating out of the base glaze. With the Ti3+ providing
most of the blue, and the drops providing the opalescence. Possibly with
the foreign glass providing optimum conditions for Ti3+ to occur.
Craig Martell on thu 31 oct 02
Hi:
I've been reading the posts on rutile blue glazes.
One thing that folks have been saying about this type of glaze is that they
sometimes get brown and beige pots instead of the blue. So, I was working
at the gallery yesterday and I looked at some of the rutile blue pots that
we have. Some friends of ours do rutile blues with iron reds on a light
iron bearing stoneware. On heavily textured handles, the glaze is light
brown on the raised areas and blue where it pools in the recesses. My
observations tell me that like so many iron and titanium glazes,
application is very important. If rutile blues are applied too thin, there
isn't enough depth for the light refraction to take place and procuce the
blue. There needs to be a certain amount of "body" and depth to this glaze
to allow light to refract in the glaze matrix and then it will show you
"blue light". I've seen chuns do this too. My experience with chun blues
isn't extensive but more than I have with rutile blues. I look at these
glazes a lot though. If a chun is applied thinly, same deal, you don't get
the light refraction "chun blue" effect. As has been discussed, there are
a lot of other factors involved too.
regards, Craig Martell Hopewell, Oregon
Edouard Bastarache Inc. on wed 13 dec 06
My experience with a rutile blue glaze :
http://rutileblue.blogspot.com/
Later,
Edouard Bastarache
Le Fran=E7ais Volant
The Flying Frenchman
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.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/30058682@N00/
http://www.ceramique.com/cerambooks/rayons/technologie.php
Ivor and Olive Lewis on mon 24 sep 07
Dear Friends
In the normal course of events, if you were calculating the Unity =
Formula for a glaze that contained a significant amount of Rutile, how =
would you classify Titanium Dioxide. Should it be put in with the =
Alkalies and Alkali Earths, with the amphoterics like Al2O3, Fe2O3 or =
with the Silica, as an acidic ingredient ?
I would like to know how we consider its function in a glaze. Flux? =
Structural? Glass Former?
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Hank Murrow on mon 24 sep 07
On Sep 23, 2007, at 11:54 PM, Ivor and Olive Lewis wrote:
> Dear Friends
> In the normal course of events, if you were calculating the Unity
> Formula for a glaze that contained a significant amount of Rutile,
> how would you classify Titanium Dioxide. Should it be put in with
> the Alkalies and Alkali Earths, with the amphoterics like Al2O3,
> Fe2O3 or with the Silica, as an acidic ingredient ?
Dear Ivor;
I always consider Titania an RO2 ingredient.
> I would like to know how we consider its function in a glaze. Flux?
> Structural? Glass Former?
As above, with Boron, Silica, and Phosphorus, in the network forming
group.
Their Ionic Potential supports this view, along with how they behave
in the melt.
Cheers, Hank
www.murrow.biz/hank
Edouard Bastarache Inc. on mon 24 sep 07
Hello Ior,
with Silica, as in GlazeChem by Bob Wilt.
Gis la revido,
(A la revoyure)
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://perso.orange.fr/smart2000/livres.htm
http://www.pshcanada.com/Toxicology.htm
http://www.ceramique.com/librairie/
http://www.flickr.com/photos/30058682@N00/
http://myblogsmesblogs.blogspot.com/
Ivor and Olive Lewis on tue 25 sep 07
Dear Edouard,
Thank you for that information.
Can you tell me why this is so ? Hutchinson-Cuff tells us that Titanium =
Dioxide is almost insoluble in a Silicate melt so it would seem to be =
difficult for it to form a glass phase.
Ivor
Ivor and Olive Lewis on tue 25 sep 07
Dear Hank Murrow ,
Thank you for your information. We should put it in the RO2. That seems =
logical.
Your say <<...Their Ionic Potential supports this view, along with how =
they behave
in the melt....>> Is this your observation regarding TiO2?
Is Ionic Potential the same thing as Ionisation Potential, that is, the =
energy needed to remove the first electron from the atom?=20
The phase diagram for SiO2-TiO2 shows that, for all compositions, =
segregation of both compounds takes place during cooling, to give a =
mixture of Cristobalite and Rutile. The fact that Rutile and Titanium =
Dioxide are used as opacifiers seems to indicate that either TiO2 does =
not melt because its melting point is very high in comparison to =
glazing temperatures or it does not dissolved in an alkali-Silicate =
melt.
Best regards,
Ivor
Edouard Bastarache Inc. on tue 25 sep 07
Hello Ivor,
I have no idea why Bob Wilt did so.
If he is still a member of the list,
he could explain why.
Gis la revido,
(A la revoyure)
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://perso.orange.fr/smart2000/livres.htm
http://www.pshcanada.com/Toxicology.htm
http://www.ceramique.com/librairie/
http://www.flickr.com/photos/30058682@N00/
http://myblogsmesblogs.blogspot.com/
John Sankey on tue 25 sep 07
Ivor is correct to question the role of TiO2 in glazes. Appen
found it to have a highly variable thermal expansion coefficient
depending on concentration, which is a strong indication that its
role depends on that.
In fact, the extent of disagreement over the expansions of the
entire RO2 group is unsettling - see
http://sankey.ws/glazeexpansion.html#RO2
for a summary.
I feel it's worth checking the group out further. Anyone who
wants to join me is very welcome.
In this regard, it appears that Appen published in Russian, as
the only source I know of his data is Technology of Enamels,
Vargin, translated from the Russian. There are no references at
all in the translation except for one chapter added by the
translator. If anyone is able to locate Appen's original
publication(s) even in Russian (which I can handle), it would
help the quest a great deal.
--
Include 'Byrd' in the subject line of your reply
to get through my spam filter.
John Hesselberth on tue 25 sep 07
On Sep 24, 2007, at 2:54 AM, Ivor and Olive Lewis wrote:
> In the normal course of events, if you were calculating the Unity
> Formula for a glaze that contained a significant amount of Rutile,
> how would you classify Titanium Dioxide. Should it be put in with
> the Alkalies and Alkali Earths, with the amphoterics like Al2O3,
> Fe2O3 or with the Silica, as an acidic ingredient ?
> I would like to know how we consider its function in a glaze. Flux?
> Structural? Glass Former?
Hi Ivor,
In terms of organizing the presentation of the unity formula I
include it in the same section as silica; however I would never
combine its level with that of silica. It is reported to only be
soluble in a silica melt to about 1% so has very little importance to
the chemistry. Its primarily role from my perspective is as a
crystalization aid by providing "seeds".
It also can have an important effect on the optical properties of a
glaze, but that is probably physics, not chemistry.
Regards,
John
John Hesselberth
www.frogpondpottery.com
"Man is a tool-using animal....without tools he is nothing, with
tools he is all" .... Thomas Carlyle
Hank Murrow on wed 26 sep 07
On Sep 26, 2007, at 6:29 PM, Ron Roy wrote:
> Hi Hank,
>
> I assume you mean alumina - not silica in the network forming group?
>
> RR
No, Ron;
I have always considered Silica, Boron, and Phosphorus to be network
formers, while Al, Ti, Zr, Cr, and Fe2O3 seem like network modifiers.
I base these distinctions/classifications on their Ionic Potential
(valency divided by ionic radius); where an Ionic Potential above 7
would be in the network/glass-forming group, while those with IPs
between 7 and around 3 are network modifiers(stiffeners). Fluxes
(network modifiers also) have IPs below 3, such as Li, Na, K, Mg, Ba,
Ca, Mn, Sr, & Zn, which fall into that category in my experience.
I did a very interesting Currie grid Tile where P2O5 was very
prominent and silica very low........ the result was an area way to
the left of the tile with lovely melts. An effective demonstration of
the Glass forming nature of P2O5. Converted Mr. Currie with it.
Haven't gotten anyone to re-write their calculation software in
recognition of this yet.
Love your work for Clayart!
Cheers, Hank
Ivor and Olive Lewis on wed 26 sep 07
Dear John Sankey,
Thank you for your support on this topic.
Regarding Thermal Expansion, I take you are familiar with Ch 12 of =
"Introduction to Ceramics" by Kingery, Bowen and Uhlmann which relates =
to thermal properties. They give some information that seems useful.
Relating to Titania, on p 99 these authors class Ti in the form M in M0x =
as an "Intermediate" compound and do not list it with the "Glass =
Formers"=20
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ivor and Olive Lewis on wed 26 sep 07
Dear John Hesselberth,
Thank you for your response. I am reaching the same opinion and agree =
that what we experience seems more to do with Physics than Chemistry.
One thing that is becoming clear is that Soda compounded with Silica as =
Na2O.SiO2, one of the Sodium Silicates, has the ability to influence the =
degree to which Titania can be adsorbed into a melt. The effect of this =
seems to be to increase optical refractivity and the glass which forms =
has about 30% TiO2 and an RI of about 1.8, where Quartz is about 1.5.
Best regards,
Ivor
Ron Roy on wed 26 sep 07
Hi Ivor,
In a way it is misleading to include it at all in terms of describing the
glass - as it takes so little part. It is a glass former but does not melt.
On the other hand we found it had an effect on durability.
When I calculate glazes with zircopax (does not melt either) I exclude it -
because the silica does not become part of the glaze - so it does not help
durability in that sense. Calculation programs mistakenly assume the silica
in the zircopax becomes part of the glaze. It does have some influence on
expansion however so I include it in that case.
I do believe that there is something to learn by including TiO2 in the
calculation because of the other characteristics it brings to a glaze. How
much will produce opacity for instance. And it also affects expansion even
though it does not go into solution.
In the case of Rutile - you would certainly like to know how much iron is
added with the rutile.
In the end - it is certainly not a flux or a glaze former at our
temperatures - does that put it in the same class as alumina? It's
beginning to sound like a conversation about boron!
I believe that no matter how we look at the molecular formula we will learn
about glazes.
RR
>In the normal course of events, if you were calculating the Unity Formula
>for a glaze that contained a significant amount of Rutile, how would you
>classify Titanium Dioxide. Should it be put in with the Alkalies and
>Alkali Earths, with the amphoterics like Al2O3, Fe2O3 or with the Silica,
>as an acidic ingredient ?
>I would like to know how we consider its function in a glaze. Flux?
>Structural? Glass Former?
>Best regards,
>Ivor Lewis.
>Redhill,
>South Australia.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on wed 26 sep 07
Hi Hank,
I assume you mean alumina - not silica in the network forming group?
RR
>I always consider Titania an RO2 ingredient.
>
>> I would like to know how we consider its function in a glaze. Flux?
>> Structural? Glass Former?
>
>As above, with Boron, Silica, and Phosphorus, in the network forming
>group.
>
>Their Ionic Potential supports this view, along with how they behave
>in the melt.
>
>Cheers, Hank
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ivor and Olive Lewis on thu 27 sep 07
Dear Ron Roy ,
Thank you for your comments.
With regard to the Fe^2+ content of Rutile, Dana suggests that it will =
be less that 10 % and that there may be Fe^3+ as well.
The TiO2-Al2O3-SiO2 phase diagram makes interesting reading. This shows =
that there is no reaction between Silicon dioxide and Rutile but =
Titanium Aluminate will form in mixtures with less than 80% SiO2, more =
that 10% Rutile and more than 10% Alumina. Which seems to suggest that =
in this environment it has Basic qualities. However, with regard to many =
other bases it has acidic behaviour and forms Titanates.
Not in the same class as Alumina. As far as I know there is a chemical =
reaction between Silica and Alumina when their melt cools which gives us =
Mullite whereas there is no such reaction between Rutile and Silicon =
dioxide.=20
Good to hear from you again.
Best regards,
Ivor
Bruce Girrell on thu 27 sep 07
Ron Roy wrote
> It is a glass former but does not melt.
Are you speaking of rutile, or TiO2?
I have watched rutile melt. It's stubborn, but it melts. And my glazes don't
look their best until it does.
I can agree, however, that the issue here may have more to do with physics
than chemistry.
Bruce Girrell
Ron Roy on sun 30 sep 07
Hi Hank,
OK - I'm interested - how would I calculate the ionic potential for the
following? Do put the fluxes in unity?
3134 - 20
G200 - 20
Dolomite - 20
EPK - 20
Silica - 20
Total - 100
Have you done any testing to find out how stable a high Phosphorus glaze
would be?
P205 has an estimated expansion 15 times that of SiO2 - is your high P2O5
glaze crazing?
RR
>> Hi Hank,
>>
>> I assume you mean alumina - not silica in the network forming group?
>>
>> RR
>
>No, Ron;
>
>I have always considered Silica, Boron, and Phosphorus to be network
>formers, while Al, Ti, Zr, Cr, and Fe2O3 seem like network modifiers.
>I base these distinctions/classifications on their Ionic Potential
>(valency divided by ionic radius); where an Ionic Potential above 7
>would be in the network/glass-forming group, while those with IPs
>between 7 and around 3 are network modifiers(stiffeners). Fluxes
>(network modifiers also) have IPs below 3, such as Li, Na, K, Mg, Ba,
>Ca, Mn, Sr, & Zn, which fall into that category in my experience.
>
>I did a very interesting Currie grid Tile where P2O5 was very
>prominent and silica very low........ the result was an area way to
>the left of the tile with lovely melts. An effective demonstration of
>the Glass forming nature of P2O5. Converted Mr. Currie with it.
>Haven't gotten anyone to re-write their calculation software in
>recognition of this yet.
>
>Love your work for Clayart!
>
>Cheers, Hank
>
>______________________________________________________________________________
>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 melpots2@visi.com
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on sun 30 sep 07
Hi Bruce,
I'm just going by the books - do you mean rutile is no longer an opacifier
- how much do you have in your glaze? Is it reduced?
I'm trying to understand how you can melt rutile - is it high iron?
I have not seen illmanite melt (a high iron form of TiO2) except in am over
fluxed glaze in oxygen.
I'm not saying you don't melt it but I would like to understand why - would
you send me the recipe of the glaze?
RR
>Ron Roy wrote
>
>> It is a glass former but does not melt.
>
>Are you speaking of rutile, or TiO2?
>
>I have watched rutile melt. It's stubborn, but it melts. And my glazes don't
>look their best until it does.
>
>I can agree, however, that the issue here may have more to do with physics
>than chemistry.
>
>Bruce Girrell
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Hank Murrow on sun 30 sep 07
On Sep 30, 2007, at 3:25 PM, Ron Roy wrote:
> Hi Hank,
>
> OK - I'm interested - how would I calculate the ionic potential for
> the
> following? Do put the fluxes in unity?
>
> 3134 - 20
> G200 - 20
> Dolomite - 20
> EPK - 20
> Silica - 20
> Total - 100
Dear Ron;
With the exception of Silica, these are all compounds of ions, and
since the IP applies only to the single positive ion as it
participates in a network, I am not sure how to calculate the rest.
Silica has a valence of +4 and an ionic radius of .39; so 4 divided
by .39 is 10.26....... an IP well into the glass forming realm.
Phosphorus has a valence of 5 and an ionic radius of .35, so it has a
Ionic Potential of 14.29, higher than Silica.
The fluxes are much lower in IP, as in the example of Potassium,
which has a valence of +1 and an ionic radius of 1.33, so an Ionic
Potential of .75....... so it will disrupt a silicon network if
heated to melting. Sodium has an IP of 1, and Lithium 1.3, Barium
1.4, Calcium 2.0, Magnesium 2.6, and Strontium 1.8.
My metaphor for how IP works in the melt is a box of marbles. if the
Silica-sized marbles are next to Oxygen-sized marbles in a
tetrahedral network, it will take a huge amount of shaking(heat) to
loosen the network(box of close-packed marbles). And if you do shake
it up, and then throw in some of those big K or Na ions, they will
disrupt the close-packed network and lower the energy required to
melt the network.
>
> Have you done any testing to find out how stable a high Phosphorus
> glaze
> would be?
Not on a wide scale, but Cory's Weird is stable in testing so far. In
addition, I have been using plates glazed with it(32% bone ash) for
40 years with NO change in appearance......... looking like they just
came out of the fire. I could send you one to check out if you will
send it back.
>
> P205 has an estimated expansion 15 times that of SiO2 - is your
> high P2O5
> glaze crazing?
Sometimes. Seems to be fine on some clays though. Very clay-dependent.
Cheers, Hank
www.murrow.biz/hank
Ivor and Olive Lewis on mon 1 oct 07
Dear Ron and Hank,
Kingery and his co-authors give a list of elements that contribute to =
Oxides of the form MOx and classes them as Glass Formers, Intermediates =
and Modifiers.The data presented allows us to consider Valance, =
Dissociation Energy, Coordination number and Single Bond Strength. It =
would seem to be the latter parameter that governs the ability of an =
oxide to form a glass structure.
Titanium is at the top of the list of Intermediate Ions, pushed out of =
the Glass formers by Zirconium.
Lists of Compounds give us some insight. Titanium Dioxide, as TiO2, =
appears to have Amphoteric qualities since it can form Titanates with =
several metals including Manganese and Iron.
Phase diagrams also give some interesting insights. Titanium Dioxide is =
soluble at elevated temperatures is molten Sodium Silicate forming a =
compound which would appear to be Na2O.TiO2.SiO2 that has a melting =
point of 970 deg C.=20
But closer to home in the realms of glaze technology is information from =
the Na2O-CaO-Al2O3- SiO2-TiO2 system. Depending on composition the =
solidification temperature can be as low as 1200 deg C and well within =
the potters firing range at 1300. Information suggests that samples =
throughout the range of mixtures will solidify as Glasses.
This indicates to me that rather than melting, Rutile and possibly =
Titanium dioxide will dissolve in an aggressively fluxed silicate =
fusion.
By the way, Chappell's Floating Blue has 4% Rutile, 2% RIO and 1% Cobalt =
Oxide. So what are the odds on Rutile doing no more than modify a harsh, =
strident Cobalt blue.
Best regards to you both,
Ivor Lewis.
Redhill,
South Australia.
Bruce Girrell on mon 1 oct 07
Ron Roy asked about the rutile glazes that I use (his post is below my sig)
My observations are based on drawrings that I use along with cones to judge
when a firing is complete.
I pull the first ring when I hit ^10 and continue until microscopic
examination of the drawring shows that the rutile has melted.
We have achieved our most successful results using Pete Pinnel's Cash Blue
layered over Rutile Blue 51 from Big Creek Pottery. Since the
Rutile Blue 51 recipe is heavy in iron, you can't really see into it very
well. It is a dark brown at ^10. We also use Cash Blue over Woo Blue, which
is also heavy in iron.
My observations, then, are based on examination of the Cash Blue layer,
which is quite transparent at ^10. The drawrings are dipped like the pots:
RB51 first, then CB on top, though I tilt the rings, first one way for the
RB51, then the
other for the CB, as I dip them so that there is a little bit of each glaze
that is
single layer. Melting in the single layer portion appears to be no different
from that
in the layered portion. Other experiments indicate that the thickness of the
RB51 is not very important, but that the CB should not be thin. Otherwise
the glaze does not flow properly and I consider flowing to be important in
achieving the effect that I like.*
Cash Blue, cone 10 (from Pete Pinnell)
47.3 Nepheline Syenite
14.2 Gertsley Borate
27.5 Flint
9.3 Whiting
1.7 Zinc Oxide
+4 Rutile
#51 Rutile Blue, from Big Creek Pottery, Davenport, California, 1973
Thanks also to David Hendley
Custer Feldspar .....357
Flint.....436
Whiting.....159
Kaolin.....137
Red Iron Oxide.....50
Rutile.....50
These glazes are fired in reduction along with other glazes that like
reduction. I start a sooty environment below 500C for the purpose of
promoting carbon trapping in our shinos. As I get above red heat I open the
damper to improve combustion efficiency, but (since my Oxyprobe has died)
keep the environment reducing enough that a kitchen match held at a peep
hole will not burn after the oxidizers in the match head are consumed. This
level of reduction is maintained until completion of the firing (rutile is
melted) at which point I cut back on the burners and slowly allow the kiln
to move into oxidation as it cools.
If the melting were due to fluxing by the iron content, wouldn't we expect
ilmenite to melt better than rutile? My observations parallel yours - I have
observed only marginal melting of ilmenite, though the particle size of the
ilmenite is much larger than that of my rutile.
I would appreciate any comments you have regarding these glazes. I can send
you photomicrographs if you are interested.
Bruce Girrell
* Often this flow results in the glazes running off the pot and I was
doubting if I was doing things "right". The layering of the two different
types of glazes and the high temperatures - up to ^13 - made me wonder if
there weren't a better way. But two pieces of evidence indicate that I might
be doing at least some of the right things.
One gallery in Traverse City carries pieces made by Bill Campbell. Bill
Campbell seems to have rutile blues nailed. In some verbiage that the
gallery has regarding his work, Bill mentions that he layers his glazes.
Nice to know that. It probably doesn't mean much to most people who read
that info sheet, but it meant a lot to me.
The second piece of information came when I was visiting the exhibits at
NCECA this year in Louisville. I was talking to the people who were selling
Advancer kiln shelves. At some point in the conversation the sales rep
pulled out a photo a kiln, loaded with Advancer shelves. Lo and behold, it
was Bill Campbell's kiln and the glazes were running off of the pots and on
to the shelves. Although the sales rep was enthusiastically explaining how
the glaze simply pops off of the shelves, I was ecstatic to see that someone
who was getting good rutile blue results was doing it a lot like I was.
Ron's post:
> I'm just going by the books - do you mean rutile is no longer an opacifier
> - how much do you have in your glaze? Is it reduced?
>
> I'm trying to understand how you can melt rutile - is it high iron?
>
> I have not seen illmanite melt (a high iron form of TiO2) except in am
over
> fluxed glaze in oxygen.
>
> I'm not saying you don't melt it but I would like to understand why -
would
> you send me the recipe of the glaze?
Chic Lotz + keith Montgomery on tue 2 oct 07
Thanks for the great debate on rutile blues! I love finding out what
others have learned.
I've been watching my rutile blue glaze for years.........its one of
my favorites. What I noticed is the rutile finally seems to "melt"
in heavy reduction around cone 12. (in a wood firing is best.)
That's my favorite.
From what I've observed.......that's when it appears to move from
opacity to transparency. Its transparent where thin on the
surface......... and bluish white opaque where thick in the crevices
of a texture. If its in a kiln spot that didn't get hot enough OR
reduced enough.........then the rutile remains opaque. I agree with
Bruce....my rutile glaze doesn't look its best until the rutile
"melts"...........those are my racers! Sometimes a second firing can
turn a mediocre one into a racer.
Chic Lotz
www.GlazeBasics .com
Ron Roy wrote
> It is a glass former but does not melt.
Bruce Girrell wrote:
Are you speaking of rutile, or TiO2?
I have watched rutile melt. It's stubborn, but it melts. And my
glazes don't
look their best until it does.
I can agree, however, that the issue here may have more to do with
physics
than chemistry.
Bruce Girrell
Ron Roy on wed 3 oct 07
Hi Hank, thanks for this.
So if you don't calculate - how do you use IP for glazes except to describe
what happens. Can you use it to predict durability and/or expansion?
RR
>Dear Ron;
>
>With the exception of Silica, these are all compounds of ions, and
>since the IP applies only to the single positive ion as it
>participates in a network, I am not sure how to calculate the rest.
>Silica has a valence of +4 and an ionic radius of .39; so 4 divided
>by .39 is 10.26....... an IP well into the glass forming realm.
>Phosphorus has a valence of 5 and an ionic radius of .35, so it has a
>Ionic Potential of 14.29, higher than Silica.
>
>The fluxes are much lower in IP, as in the example of Potassium,
>which has a valence of +1 and an ionic radius of 1.33, so an Ionic
>Potential of .75....... so it will disrupt a silicon network if
>heated to melting. Sodium has an IP of 1, and Lithium 1.3, Barium
>1.4, Calcium 2.0, Magnesium 2.6, and Strontium 1.8.
>
>My metaphor for how IP works in the melt is a box of marbles. if the
>Silica-sized marbles are next to Oxygen-sized marbles in a
>tetrahedral network, it will take a huge amount of shaking(heat) to
>loosen the network(box of close-packed marbles). And if you do shake
>it up, and then throw in some of those big K or Na ions, they will
>disrupt the close-packed network and lower the energy required to
>melt the network.
>>
>> Have you done any testing to find out how stable a high Phosphorus
>> glaze
>> would be?
>
>Not on a wide scale, but Cory's Weird is stable in testing so far. In
>addition, I have been using plates glazed with it(32% bone ash) for
>40 years with NO change in appearance......... looking like they just
>came out of the fire. I could send you one to check out if you will
>send it back.
>>
>> P205 has an estimated expansion 15 times that of SiO2 - is your
>> high P2O5
>> glaze crazing?
>
>Sometimes. Seems to be fine on some clays though. Very clay-dependent.
>
>Cheers, Hank
>www.murrow.biz/hank
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Hank Murrow on wed 3 oct 07
On Oct 2, 2007, at 10:37 PM, Ron Roy wrote:
> Hi Hank, thanks for this.
>
> So if you don't calculate - how do you use IP for glazes except to
> describe
> what happens. Can you use it to predict durability and/or expansion?
Dear Ron;
No, I don't use Ionic Potential to determine expansion or durability.
I find it very useful in explaining to myself how things melt or
don't melt. By the way, Phosphorus, as used in Cory's Weird at cone
10R, seems to be the most durable glaze I have used. I think P2O5 is
a fascinating glass former, and it has a permanent honored place on
my glaze bench. the problem is getting sources other than bone ash.
Cheers, Hank
>> Dear Ron;
>>
>> With the exception of Silica, these are all compounds of ions, and
>> since the IP applies only to the single positive ion as it
>> participates in a network, I am not sure how to calculate the rest.
>> Silica has a valence of +4 and an ionic radius of .39; so 4 divided
>> by .39 is 10.26....... an IP well into the glass forming realm.
>> Phosphorus has a valence of 5 and an ionic radius of .35, so it has a
>> Ionic Potential of 14.29, higher than Silica.
>>
>> The fluxes are much lower in IP, as in the example of Potassium,
>> which has a valence of +1 and an ionic radius of 1.33, so an Ionic
>> Potential of .75....... so it will disrupt a silicon network if
>> heated to melting. Sodium has an IP of 1, and Lithium 1.3, Barium
>> 1.4, Calcium 2.0, Magnesium 2.6, and Strontium 1.8.
>>
>> My metaphor for how IP works in the melt is a box of marbles. if the
>> Silica-sized marbles are next to Oxygen-sized marbles in a
>> tetrahedral network, it will take a huge amount of shaking(heat) to
>> loosen the network(box of close-packed marbles). And if you do shake
>> it up, and then throw in some of those big K or Na ions, they will
>> disrupt the close-packed network and lower the energy required to
>> melt the network.
>>>
>>> Have you done any testing to find out how stable a high Phosphorus
>>> glaze
>>> would be?
>>
>> Not on a wide scale, but Cory's Weird is stable in testing so far. In
>> addition, I have been using plates glazed with it(32% bone ash) for
>> 40 years with NO change in appearance......... looking like they just
>> came out of the fire. I could send you one to check out if you will
>> send it back.
>>>
>>> P205 has an estimated expansion 15 times that of SiO2 - is your
>>> high P2O5
>>> glaze crazing?
>>
>> Sometimes. Seems to be fine on some clays though. Very clay-
>> dependent.
>>
>> Cheers, Hank
>> www.murrow.biz/hank
>
>
Ivor and Olive Lewis on mon 15 oct 07
Dear Bruce Girrell,=20
I have been studying your description of the way you prepare your draw =
rings and would like to ask about the nature of the blue colouration .
Is the nature of your blue, in terms of Hue, Intensity and Tonal value, =
variable? Is the blue neutral without nuances of green or violet? Is it =
a strong colour or weak and pale? is the tone light or dark? Please =
confirm that your best effect is a truly transparent glaze.=20
Do you get the same effect where there is only Cash Blue as you do where =
there is only #51 Cash blue?
Is the nature of the colour different where there are layers of =
differing glaze ?
How would the hue, intensity and tone compare to say a standard =
transparent glaze with 1.0% Cobalt oxide? or Cobalt bottle glass Or =
something like Cobalt blue oil paint.
In asking these questions I wish to eliminate the possibility that =
colour is due to a Chun effect induced by Gerstley Borate and have a =
clear understanding of the power of the blue you observe.=20
Best regards,
Ivor
mel jacobson on tue 9 sep 08
i find the subject from david hendley and `smarty pants` girrell fascinating.
i hope others read it and understand it.
layers...thickness, i bit over fired. a great base glaze.
all make for interesting glazed pots.
rutile is a maverick glaze. it does many things, for
many potters. hard to duplicate. each finds
a system...if you can. it does make crystals.
i think the campbell pottery is a mix of rutile blue and
crystal glazes...almost all in one. (oxymornon)
it is really interesting.
i am one of those folks that really admires bill campbell.
he is just out there, doing his thing...making money with
pots...hires good people. he does not give a sh** what others
think. does what he wants to do...sells what people want
and sells a great deal of it. he has a great formula and sticks
with it. just does not get caught up in philosophy and bs.
he is an old time potter. he knows what he is about.
it would be fun to compare check books with some of the
`holier than thou` types. i do admire folks that make pots.
and know what they are doing.
mel
from minnetonka:
website http://www.visi.com/~melpots/
clayart site:
http://www.visi.com/~melpots/clayart.html
KATHI LESUEUR on tue 9 sep 08
On Sep 9, 2008, at 6:47 PM, mel jacobson wrote:
>
> i am one of those folks that really admires bill campbell.
> he is just out there, doing his thing...making money with
> pots...hires good people. he does not give a sh** what others
> think. does what he wants to do...sells what people want
> and sells a great deal of it. he has a great formula and sticks
> with it.
He's also incredibly generous with his time and knowledge. I've
visited his studio several times,. There was no question he wouldn't
answer. No technique he wouldn't explain. Those who bash him instead
of learning from him lose out in the end.
Kathi
Bill Merrill on tue 30 sep 08
Over the last few months there has so much been written about "floating
Blue". The whole street fair scene is a mass of "Floating Blue". Has
anyone done line blends on that glaze using different materials?
Blending the blue with matt glazes can be quite beautiful. Blending the
blue with satin mats and glossy glazes also produce some great results.
Porcelain or stoneware bodies will change those glazes greatly. Like
any glaze there seems to be a run of potters using a particular glaze.
Shaner Red was a glaze like that. For the most part potters got a green
from it rather than red. It was mysterious and took certain firings,
the proper thickness, a not too dark iron bearing body and the proper
firing schedule and final temperature to achieve a good, clear iron red.
The thing is to work on developing a glaze from the original that works
for you. Glaze testing isn't merely taking a glaze from a book, mixing
it and putting it on a pot. It takes more than that too achieve your
dream glaze.
=20
Many years ago there was a light tone rutile being made. It was a
beautiful orange color. It didn't change the glaze much, but I like to
decorate glazes using colemanite (60) and rutile(40). The light tone
rutile was discontinued so I called the manufacturer=20
and found that the light tone rutile was re-fired to a
low temperature. I fired some regular rutile to about 1300 degrees
Fahrenheit and it looked like the orange light tone rutile. I liked it
because it showed up on the glaze better than the regular rutile.
=20
. =20
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Loren JOnes on wed 21 apr 10
We are using a rutile blue glaze at the high school I work at. It is Rutile=
=3D
Blue II listed in John Britts book on high fire glazes. We=3DA0have been g=
et=3D
ting really bad results lately. It comes out this dirty clear with some mil=
=3D
ky blue=3D0Awhere it is thickest. What does this glaze want to be happy? Is=
t=3D
his too thin an application? Is it not being reduced at the right time/temp=
=3D
? Can any of you shed some light on this. The students are big fans of it a=
=3D
nd would like to see it come out like the test tiles!=3D0ACuster Spar=3DA0=
=3DA0 3=3D
0%=3D0AWhiting=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA011.1%=3D0ASilica=
=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3D
=3DA0=3DA0=3DA0=3DA0=3DA0=3DA026.3%=3D0AEPK=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=
=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0 16.=3D
8%=3D0ADolomite=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA015.8%=3D0ARutile=3DA0=3DA=
0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3D
=3DA0=3DA0 8.0%=3D0AThanks for any and=3DA0all help. Loren=3DA0=3D0A=3D0A=
=3D0A
Sumi von Dassow on thu 22 apr 10
Loren
I don't know if this is relevant, but a couple of years ago I noticed my
rutile glazes losing some of their color. Especially a pink (oxidation)
glaze started washing out. I decided that the composition of recent
rutile deposits coming out of the mine are lacking in some component
that produces the colors that we potters like. Rutile is impure ore of
titanium, containing small amounts of iron, vanadium and chrome. I
started mixing up my own substitute for rutile using titanium with small
amounts of these oxides added; it fixed my pink, anyway.
Sumi
> We are using a rutile blue glaze at the high school I work at. It is Ruti=
le Blue II listed in John Britts book on high fire glazes. We have been get=
ting really bad results lately. It comes out this dirty clear with some mil=
ky blue
> where it is thickest. What does this glaze want to be happy? Is this too =
thin an application? Is it not being reduced at the right time/temp? Can an=
y of you shed some light on this. The students are big fans of it and would=
like to see it come out like the test tiles!
> Custer Spar 30%
> Whiting 11.1%
> Silica 26.3%
> EPK 16.8%
> Dolomite 15.8%
> Rutile 8.0%
> Thanks for any and all help. Loren
>
>
>
>
>
>
--
Sumi von Dassow
www.herwheel.com
sumi@herwheel.com
Lis Allison on fri 23 apr 10
On Thursday 22 April 2010, you wrote:
>.... Rutile is
> impure ore of titanium, containing small amounts of iron, vanadium and
> chrome. I started mixing up my own substitute for rutile using
> titanium with small amounts of these oxides added; it fixed my pink,
> anyway.
Would you share your recipe or at least a ballpark suggestion of what to
mix up? I am having a lot of trouble with a favourite glaze and I think
the problem is the rutile. In addition to not having its usual mottling
effect, it is also causing the glaze to hardpan, which it has never done
before and I've used it for 15 years.
Lis
--
Elisabeth Allison
Pine Ridge Studio
www.Pine-Ridge-Studio.blogspot.com
Sumi von Dassow on fri 23 apr 10
Lis
I don't mind sharing, but it's at the studio where I won't be until
Tuesday. However, it's something on the order
of 100 grams of titanium dioxide plus one or two grams each of vanadium
and chrome, plus 5 grams
of red iron oxide. I use that one to one as a substitute for rutile. No,
come to think of it, I substitute it for half
the rutile just to get whatever else is in rutile. I hope I remember on
Tuesday to write it down and bring it home.
Oh, and try my cure for hard-panning: one percent pearl ash added to the
glaze. It's water-soluble so you can
easily add it to an already mixed up glaze, and it's worked for every
glaze I've ever tried it in, without changing
the fired result at all.
Sumi
> On Thursday 22 April 2010, you wrote:
>
>
>> .... Rutile is
>> impure ore of titanium, containing small amounts of iron, vanadium and
>> chrome. I started mixing up my own substitute for rutile using
>> titanium with small amounts of these oxides added; it fixed my pink,
>> anyway.
>>
>
> Would you share your recipe or at least a ballpark suggestion of what to
> mix up? I am having a lot of trouble with a favourite glaze and I think
> the problem is the rutile. In addition to not having its usual mottling
> effect, it is also causing the glaze to hardpan, which it has never done
> before and I've used it for 15 years.
>
> Lis
> --
> Elisabeth Allison
> Pine Ridge Studio
> www.Pine-Ridge-Studio.blogspot.com
>
>
>
--
Sumi von Dassow
www.herwheel.com
sumi@herwheel.com
Sumi von Dassow on sun 2 may 10
Lis and Elaine
Sorry, it took me a few days to remember to bring home the recipe for my
rutile substitute. Rutile has lots of impurities
including uranium, zirconium, tin, aluminum, niobium, and others, but I
use 100 grams of titanium plus 5 grams of red iron oxide,
and .5 grams each of vanadium and chrome as a substitute.
Sumi
>
>> .... Rutile is
>> impure ore of titanium, containing small amounts of iron, vanadium and
>> chrome. I started mixing up my own substitute for rutile using
>> titanium with small amounts of these oxides added; it fixed my pink,
>> anyway.
>>
>
> Would you share your recipe or at least a ballpark suggestion of what to
> mix up? I am having a lot of trouble with a favourite glaze and I think
> the problem is the rutile. In addition to not having its usual mottling
> effect, it is also causing the glaze to hardpan, which it has never done
> before and I've used it for 15 years.
>
> Lis
> --
> Elisabeth Allison
> Pine Ridge Studio
> www.Pine-Ridge-Studio.blogspot.com
>
>
>
--
Sumi von Dassow
www.herwheel.com
sumi@herwheel.com
Steve Slatin on tue 4 may 10
Not to be too pretentious about this (but, one
hopes, *just* pretentious enough) but rutile
is a material primarily distinguishible by
its native crystalline structure (a tetragon,
or cube) rather than by its occasional and
highly variable inclusions of trace materials.
One characteristic of all of the members of
the group of minerals to which rutile belongs
is what's called "ease of twinning" -- the=3D20
ability to form a second, daughter, crystal
from the original crystal instead of growing
a larger and larger single crystal.
If you use rutile for a glaze that does not
depend largely on the crystalline structure
of the glaze, but rather on the chemicals from
which the crystals are formed, then you may
readily substitute titanium dioxide and iron
oxide as a substitute. That crystalline
characteristic, though, may be the key to
many of the better rutile glazes.
FWIW, I've experimented with substitutions,
and never found a glaze with 2% or less rutile
that didn't substitute satisfactorily with
titanium and iron. OTOH, every glaze that I
tried with 6% or more seemed very different
with a substitution. Floating blue especially.
Steve Slatin --=3D20
--- On Sun, 5/2/10, Sumi von Dassow wrote:
> Lis and Elaine
>=3D20
> Sorry, it took me a few days to remember to bring home the
> recipe for my
> rutile substitute. Rutile has lots of impurities
> including uranium, zirconium, tin, aluminum, niobium, and
> others, but I
> use 100 grams of titanium plus 5 grams of red iron oxide,
> and .5 grams each of vanadium and chrome as a substitute.
>=3D20
> Sumi
> >
> >> .... Rutile is
> >>=3DA0 impure ore of titanium, containing small
> amounts of iron, vanadium and
> >>=3DA0 chrome. I started mixing up my own
> substitute for rutile using
> >>=3DA0 titanium with small amounts of these oxides
> added; it fixed my pink,
> >>=3DA0 anyway.
> >>
> >
> > Would you share your recipe or at least a ballpark
> suggestion of what to
> > mix up? I am having a lot of trouble with a favourite
> glaze and I think
> > the problem is the rutile. In addition to not having
> its usual mottling
> > effect, it is also causing the glaze to hardpan, which
> it has never done
> > before and I've used it for 15 years.
> >
> > Lis
> > --
> > Elisabeth Allison
> > Pine Ridge Studio
> > www.Pine-Ridge-Studio.blogspot.com
> >
> >
> >
>=3D20
>=3D20
> --
> Sumi von Dassow
> www.herwheel.com
> sumi@herwheel.com
> =3D0A=3D0A=3D0A
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