Pam on mon 11 oct 04
I think I may have found my answers in a paper posted here way back when.
It looks like the answer is to add titanium dioxide, as some rutile batches
are heavier in the iron, lighter in Ti20 than others. Boron also is a
factor.
Check out this link for some rutile answers:
http://grafik.sdsu.edu/ceramicsweb//articles/tech_handouts/titania_in_glaze.html
(c) 1994 Karl Platt
I see testing testing testing in my near future..........
Pam on mon 11 oct 04
Once upon a time, before I joined my guild, they had lovely rutile blues
(^10 reduction). Then, without changing the recipe, the blue turned to
caramel, and the glaze crazed. Other glazes needing reduction were fine, so
it is not a reduction problem. I was told that they ran many tests, and
could only conclude that something in the recipe was corrupted/contaminated.
For a while, we used this glaze anyway, changing it's name to "Carmel",
because even though it was not blue, it did interesting things over other
glazes, particularly copper red. We eventually pulled this glaze out of the
studio though, because it was runny, and a runny glaze paired with student
potters made for lots of kiln shelf scraping :-(
Recently, not knowing the full story of our guild's problems with rutile
blues, I have been testing some rutile recipes and getting the exact same
thing, instead of a variegated blue like pictures I see of rutile blues, I
get a clear, yellowish color.
My next idea is to do a line blend with a graduated increase of rutile. We
shall see how that goes.
What I am wondering is, has anyone else had troubles with rutile, and if so
did you find a solution? This has been a problem for a long time, and our
stock of chemicals has been refreshed/replaced many times, from a reputable
supplier. Could it be our city water? In recent years the h2o dept. has been
buffering our very acidic water, so when it comes out of the tap it is off
the scale in the alkaline direction (over 10 ph per my aquarium test kit)
but plunges to 5 or 6 ph within 24 hours
Pam
pam@cresswells.com
John Rodgers on mon 11 oct 04
Pam, I can't address specific problems with rutile, but I will tell you
this.
Floating Blue at cone 6 is my principle blue glaze. It uses rutile. I
ran completely out of my old stock of rutile and of floating blue glaze,
and had to buy new rutile before I could mix new glaze. The new batch
of glaze with the new rutile in it IS NOT as good as it was before. The
varigation is minimal, which is a disappointment. And no matter how I
fire this new batch, or apply this new batch. It ain't like it use'ta as
the lil boy sez.
Regards,
John Rodgers
Chelsea, AL
Pam wrote:
>Once upon a time, before I joined my guild, they had lovely rutile blues
>(^10 reduction). Then, without changing the recipe, the blue turned to
>caramel, and the glaze crazed. Other glazes needing reduction were fine, so
>it is not a reduction problem. I was told that they ran many tests, and
>could only conclude that something in the recipe was corrupted/contaminated.
>For a while, we used this glaze anyway, changing it's name to "Carmel",
>because even though it was not blue, it did interesting things over other
>glazes, particularly copper red. We eventually pulled this glaze out of the
>studio though, because it was runny, and a runny glaze paired with student
>potters made for lots of kiln shelf scraping :-(
>Recently, not knowing the full story of our guild's problems with rutile
>blues, I have been testing some rutile recipes and getting the exact same
>thing, instead of a variegated blue like pictures I see of rutile blues, I
>get a clear, yellowish color.
>My next idea is to do a line blend with a graduated increase of rutile. We
>shall see how that goes.
>What I am wondering is, has anyone else had troubles with rutile, and if so
>did you find a solution? This has been a problem for a long time, and our
>stock of chemicals has been refreshed/replaced many times, from a reputable
>supplier. Could it be our city water? In recent years the h2o dept. has been
>buffering our very acidic water, so when it comes out of the tap it is off
>the scale in the alkaline direction (over 10 ph per my aquarium test kit)
>but plunges to 5 or 6 ph within 24 hours
>Pam
>pam@cresswells.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.
>
>
>
Darlene Yarnetsky-Mudcat Pottery on tue 12 oct 04
Hi Pam!
I had a simple cone 6 tan glaze. Used it for 2 years at least.
Suddenly around March it stopped working. I was clueless. Thought I
had made a mixing mistake. Remixed, fired, still different. Repeated
again. same result. I thought I had gotten into a different bag of
iron. Got new bag. Still no problem. Finally ordered a new bag of
rutile. Just when I had gotten used to the new glaze, there it was,
the glaze I had lost. I had bought rutile from a different supplier
and while it had no noticable effect on all of my other glazes, it
affected just this one. When I got rutile from the original supplier
again it worked the same.
I seem to remember a long ongoing discussion a few years back about
just this problem - someone needed a certain rutile and how crucial the
rutile was to his glazes. I think it might have been Richard Aerni.
It's been a while. I think rutile is one of our more variable
materials to begin with.
So the answer to the question is yes, this could be part of your
problem. To check the water, maybe try some water from a different
source. Even a couple of gallons of bottled water.
It is also possible that some other material in the recipe changed. Or
even someone could have mislabeled a material or filled a bin wrong. I
suspect some of the glaze gurus will have more ideas for you.
Best of luck!
Darlene Y. in Madison Indiana, USA where we are forecast for 4 days of
rain after more than 4 weeks without!
Gail Phillips on tue 12 oct 04
Maybe I will have trouble with rutile, too - while combining all of my glaze materials from various sources, I noticed that the rutile I dumped from a small container into my big one was quite a bit lighter in color. This remains to be seen.
- Gail Phillips, Praying Mantis Pottery (.com)
Finally ordered a new bag of
> rutile. Just when I had gotten used to the new glaze, there it was,
> the glaze I had lost. I had bought rutile from a different supplier
> and while it had no noticable effect on all of my other glazes, it
> affected just this one. When I got rutile from the original supplier
> again it worked the same.
Cynthia Bracker on tue 12 oct 04
Hi Pam,
Did your trouble start around the beginning of this year? My guess is
you are talking about the Kansas City Clay Guild, which would make us
the supplier. I looked into their purchasing records and they have
always ordered Light Tone Ceramic Grade Rutile. In December of 2003
(the last time they ordered rutile), whomever placed the order got
Milled Rutile. The biggest difference is that the former has a good
deal of more pure titanium than the latter. My guess is that this could
be what's making the difference.
You might try testing the same glaze with different rutiles and see what
happens. Also, call or e-mail me with the recipe. I'll let you know if
there are any other materials that the Guild has changed recently.
Good luck!
Cindy
Pam wrote:
>Once upon a time, before I joined my guild, they had lovely rutile blues
>(^10 reduction). Then, without changing the recipe, the blue turned to
>caramel, and the glaze crazed. Other glazes needing reduction were fine, so
>it is not a reduction problem. I was told that they ran many tests, and
>could only conclude that something in the recipe was corrupted/contaminated.
>For a while, we used this glaze anyway, changing it's name to "Carmel",
>because even though it was not blue, it did interesting things over other
>glazes, particularly copper red. We eventually pulled this glaze out of the
>studio though, because it was runny, and a runny glaze paired with student
>potters made for lots of kiln shelf scraping :-(
>Recently, not knowing the full story of our guild's problems with rutile
>blues, I have been testing some rutile recipes and getting the exact same
>thing, instead of a variegated blue like pictures I see of rutile blues, I
>get a clear, yellowish color.
>My next idea is to do a line blend with a graduated increase of rutile. We
>shall see how that goes.
>What I am wondering is, has anyone else had troubles with rutile, and if so
>did you find a solution? This has been a problem for a long time, and our
>stock of chemicals has been refreshed/replaced many times, from a reputable
>supplier. Could it be our city water? In recent years the h2o dept. has been
>buffering our very acidic water, so when it comes out of the tap it is off
>the scale in the alkaline direction (over 10 ph per my aquarium test kit)
>but plunges to 5 or 6 ph within 24 hours
>Pam
>pam@cresswells.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.
>
>
>
>
| |
|
