Marvin Klotz on fri 19 jul 02
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As volunteer lab assistant at our local junior college I have been fussing
for weeks with our ^10 reduction Rutile Pink glaze which suddenly became a
"yucky-yellowy-tan". Since I remembered opening a new bag of Gerstley
Borate just before the problem arose, its the various fluxes in the glaze
that I have been fussing with mostly - without much success. Could I
really just use TiO2 instead of rutile and get the glaze that almost all
the students love back? Rutile is the only coloring oxide in the recipe.
>One problem I am becoming quite certain of is that there is some really
>bad rutile in the hands of some of our suppliers--it must be grossly
>contaminated with iron. If you are finding ANY of your glazes going
>toward a yucky-yellowy-tan when they should be some other color, try
>replacing any rutile in the recipe with the same amount or slightly less
>of TiO2.
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John Hesselberth on fri 19 jul 02
Hi Everyone,
One of the things we get from people who buy our book is a lot of
feedback--mostly positive, but a few problems duplicating our results
here and there.
One problem I am becoming quite certain of is that there is some really
bad rutile in the hands of some of our suppliers--it must be grossly
contaminated with iron. If you are finding ANY of your glazes going
toward a yucky-yellowy-tan when they should be some other color, try
replacing any rutile in the recipe with the same amount or slightly less
of TiO2.
This has shown up several times in our Spearmint glaze which is a cool
green, but you may see the same color problem in a glaze you got from a
friend or in a book or wherever. In the cases where I heard back,
replacing the rutile with TiO2 in Spearmint has solved the problem.
Just one more reason why glazes sometimes don't travel well. I hope this
info helps someone, somewhere solve a problem.
Regards,
John
Rikki Gill on fri 19 jul 02
Do you think one can substitute Titanium dioxide for rutile across the
board, at say 5% less titanium, even in reduction firings? I use rutile
constantly, in every firing, and do notice differences. Thanks for all your
contributions to Clayart You certainly have increased my awareness of
things I don't usually think about. Rikki
----- Original Message -----
From: "John Hesselberth"
To:
Sent: Friday, July 19, 2002 8:11 AM
Subject: Rutile quality
> Hi Everyone,
>
> One of the things we get from people who buy our book is a lot of
> feedback--mostly positive, but a few problems duplicating our results
> here and there.
>
> One problem I am becoming quite certain of is that there is some really
> bad rutile in the hands of some of our suppliers--it must be grossly
> contaminated with iron. If you are finding ANY of your glazes going
> toward a yucky-yellowy-tan when they should be some other color, try
> replacing any rutile in the recipe with the same amount or slightly less
> of TiO2.
>
> This has shown up several times in our Spearmint glaze which is a cool
> green, but you may see the same color problem in a glaze you got from a
> friend or in a book or wherever. In the cases where I heard back,
> replacing the rutile with TiO2 in Spearmint has solved the problem.
>
> Just one more reason why glazes sometimes don't travel well. I hope this
> info helps someone, somewhere solve a problem.
>
> Regards,
>
> John
>
>
____________________________________________________________________________
__
> 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.
>
Ababi on sat 20 jul 02
There is a possible to change titanium into rutile in crystal glazes.
Hopefully I will be
able to tell you more after my next ^6 firing . When I will come up with
the results of a
test has been written not done yet to change rutile to titanium in a well
known recipe.
---------- Original Message ----------
>Do you think one can substitute Titanium dioxide for rutile across the
>board, at say 5% less titanium, even in reduction firings? I use rutile
>constantly, in every firing, and do notice differences. Thanks for all
your
>contributions to Clayart You certainly have increased my awareness of
>things I don't usually think about. Rikki
>----- Original Message -----
>From: "John Hesselberth"
>To:
>Sent: Friday, July 19, 2002 8:11 AM
>Subject: Rutile quality
>> Hi Everyone,
>>
>> One of the things we get from people who buy our book is a lot of
>> feedback--mostly positive, but a few problems duplicating our results
>> here and there.
>>
>> One problem I am becoming quite certain of is that there is some really
>> bad rutile in the hands of some of our suppliers--it must be grossly
>> contaminated with iron. If you are finding ANY of your glazes going
>> toward a yucky-yellowy-tan when they should be some other color, try
>> replacing any rutile in the recipe with the same amount or slightly less
>> of TiO2.
>>
>> This has shown up several times in our Spearmint glaze which is a cool
>> green, but you may see the same color problem in a glaze you got from a
>> friend or in a book or wherever. In the cases where I heard back,
>> replacing the rutile with TiO2 in Spearmint has solved the problem.
>>
>> Just one more reason why glazes sometimes don't travel well. I hope this
>> info helps someone, somewhere solve a problem.
>>
>> Regards,
>>
>> John
>>
>>
>___________________________________________________________________________
_
>__
>> Send postings to clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list or change your subscription
>> settings from http://www.ceramics.org/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
>>
>___________________________________________________________________________
___
>Send postings to clayart@lsv.ceramics.org
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Jeff Tsai on sat 20 jul 02
Hi,
I recall a while back that a rutile colored glaze a friend of mine was using
suddenly came out totally different after a new mixture was made. He figured
out that his recipe called for a "light" rutile as opposed to the rutile he
used (don't know what that kind was called).
Are there "light" and "dark" rutiles, and could such a difference be part of
the problem in recreating your glazes? I didn't pay much attention when this
happened, so this is all I remember.
-jeff
John Hesselberth on sat 20 jul 02
Hi Rikki,
I think you can probably do this substitution routinely. There is, of
course, a little iron in rutile--whether or not it is enough to affect a
reduction firing if it were missing, I don't know--I doubt it, but have
no data. The analyses I've seen are less than 1% iron. I plan to do a
few side by side tests in oxidation to see if I can see in any
meaningful difference between my rutile and TiO2.
I bet Richard Aerni would have a more informed opinion that mine since
he is something of a rutile guru. Hopefully he will chime in.
Regards,
John
On Friday, July 19, 2002, at 07:55 PM, Rikki Gill wrote:
> Do you think one can substitute Titanium dioxide for rutile across the
> board, at say 5% less titanium, even in reduction firings? I use
> rutile
> constantly, in every firing, and do notice differences. Thanks for all
> your
> contributions to Clayart You certainly have increased my awareness
> of
> things I don't usually think about. Rikki
John Hesselberth on sat 20 jul 02
Hi Jeff,
There are several grades of rutile. Richard Aerni looked into this in
depth back in March of this year--see his 3/25/02 post in the archives.
In the past, I haven't seen those differences cause the size of the
color shift we are seeing currently. I have an uneasy feeling there is
a new mine or source involved that is considerably different from the
relatively minor differences we have seen previously--but, again, I have
not data yet--only a suggestion that we all be very careful and
thoroughly test any new rutile we buy before we commit it to a big
production order.
Regards,
John
On Saturday, July 20, 2002, at 04:25 AM, Jeff Tsai wrote:
> Are there "light" and "dark" rutiles, and could such a difference be
> part of
> the problem in recreating your glazes? I didn't pay much attention when
> this
> happened, so this is all I remember.
John Hesselberth on sat 20 jul 02
Hi Marvin,
Only one way to tell. Test, test, test. The rutile issue I am raising
is not "fact". It is based on several observations and should be
regarded more as a "hypothesis". Rutile does have some other impurities
in it also. Chromium dioxide is one if I remember correctly. So your
pink color could be coming from a chrome/tin pink effect. Going to TiO2
would not give that effect if that is what you had.
Regards,
John
On Friday, July 19, 2002, at 10:39 PM, Marvin Klotz wrote:
> Could I
> really just use TiO2 instead of rutile and get the glaze that almost all
> the students love back? Rutile is the only coloring oxide in the
> recipe.
Cheryl Hoffman on sat 20 jul 02
In a message dated 7/20/02 4:27:46 AM Pacific Daylight Time,
marvintax@EARTHLINK.NET writes:
> One problem I am becoming quite certain of is that there is some really
> >bad rutile in the hands of some of our suppliers--it must be grossly
> >contaminated with iron.
Oh No! I recently purchased some new rutile from my local supplier. When I
picked up the bag, I noticed that the color was much darker than the rutile
I
was used to. I asked about it and was told that it was called dark rutile
and should give me the same results as the old stuff. Should I be suspect?
Cher Hoffman, who just spent 3 days preparing glaze line samples with the
new
rutile, trying to get a "pretty pink" glaze for my Mom (if it's not pink,
it's not pretty...she doesn't "get" the beauty of shino)
Linda Knapp on sat 20 jul 02
Yep Yep Yep!
I have done a lot of experiments lately with lots of Ti in glazes. (OK
the reason was because I bought a Ti Bicycle and it was one of those
commemorative things ;-) First thing I came up with was a long line of
tests which I named Baby Poo Brown or Baby Poo yellow. Same glazes with
TiO2 instead of Rutile came out nice.....
Linda
John Hesselberth wrote:
> Hi Everyone,
>
> One of the things we get from people who buy our book is a lot of
> feedback--mostly positive, but a few problems duplicating our results
> here and there.
>
> One problem I am becoming quite certain of is that there is some really
> bad rutile in the hands of some of our suppliers--it must be grossly
> contaminated with iron. If you are finding ANY of your glazes going
> toward a yucky-yellowy-tan when they should be some other color, try
> replacing any rutile in the recipe with the same amount or slightly less
> of TiO2.
>
> This has shown up several times in our Spearmint glaze which is a cool
> green, but you may see the same color problem in a glaze you got from a
> friend or in a book or wherever. In the cases where I heard back,
> replacing the rutile with TiO2 in Spearmint has solved the problem.
>
> Just one more reason why glazes sometimes don't travel well. I hope this
> info helps someone, somewhere solve a problem.
>
> Regards,
>
> John
>
>
____________________________________________________________________________
__
>
> 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.
>
>
Richard Aerni on sun 21 jul 02
Hello everyone,
Just got back from the most grueling show on the face of the earth, and
after an eight hour drive, opening up the house, and unloading the van, the
last thing I want to do is put together a treatise on rutile, which, it
appears, has reared it's head again.
First off, I would urge those concerned to search the archives for some of
my earlier posts on the subject, and see if they answer any of your
questions. As others have probably pointed out (I've not read many of the
hundreds of posts in my mailbox), rutile is a highly variable mineral, and
sometimes slight variations in the impurities can lead to large differences
in the fired quality of the piece.
I've not much new to add on the subject, save a couple of bits. Carla Flati
was extremely helpful a couple of months ago, and sent me many of Standard
Ceramics chemical analyses for their rutile, going back a number of years.
I was struck by the similarities in the titania and the iron content...there
were few major differences. There were what may be small but significant
differences in the quantities of some of the impurities, chrome comes to
mind first. I've not had the time to compile her data with what I've
already got from my suppliers. When I do, I'll post it all to the
list...but it may well not be til sometime in the fall.
The second bit of news is gleaned from an article I came across in the May
18, 2002 issue of The Economist, out of London. Sierra Leone, which is a
source of some very high quality rutile, which has been off the market for
some years now due to political instability, has made great progress in
ending their civil war, and successfully held elections in early May of this
year. At the time of the article, there was great optimism for political
and economic gains in that country (I haven't followed the story since
then). I'll excerpt a brief part of the article that concerns potters:
"Once the electoral euphoria subsides, reality will bite. Last year, the UN
rated Sierra Leone the worst place on earth to live. Peace alters that, of
course, but the next few months will be particularly difficult: with the
rainy season approaching, returnees will have no time to start planting
their rice and cassava, so few will produce much food this year. More
happily, the World Bank predicts that the economy will grow by 7-8% this
year, albeit from a dismally low base.
The country's diamonds, which financed the rebels' war, could now provide
jobs and tax revenues. According to a recent study, diamond exports could,
with enough investment, more than triple over the next four years, to $ 180
mil. Sierra Leone also has one of the world's richest deposits of rutile, a
mineral used in paint, which should be mined again next year."
So, hopefully, we'll get access to this deposit of rutile again with the
next year or two, if things work out right.
OK, that's it from here. I'm going to wade through a few more posts, then
get horizontal.
Best,
Richard Aerni
Bloomfield, NY
Ron Roy on sun 21 jul 02
The definition of rutile allows for certain percentages of iron with the
TiO2 - something like up to 10% iron (I don't know the exact amount) If the
titanium has more than the maximum amount I think it them must be called
illmanite - I don't know where I got this information and I'm not sure I'm
even correct - perhaps others can enlighten us.
Anyway - say you have dark rutile and you wanted to lighten it up but still
have some iron - why not add more titanium by adding in some Titanium
dioxide - I have no idea if this would work. It may even be some titanium
has too may contaminants and diluting it would still not be workable -
worth a test or two to find out I would think.
RR
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
David Hewitt on sun 21 jul 02
I would think that you have every reason to be cautious and test before
you commit it to too much of your work. Your supplier doesn't have to
live with the results of the glaze you mix with this Rutile.
Would your supplier give you an analysis of the material if you asked
him? If you could get this for every supply of Rutile that you buy I
think you would clearly see if there was a difference.
As potters I think we should all press for such information on any
suspect / variable material.
David
In message , Cheryl Hoffman writes
>In a message dated 7/20/02 4:27:46 AM Pacific Daylight Time,
>marvintax@EARTHLINK.NET writes:
>
>
>Oh No! I recently purchased some new rutile from my local supplier. Whe=
>n I
>picked up the bag, I noticed that the color was much darker than the ruti=
>le I
>was used to. I asked about it and was told that it was called dark rutil=
>e
>and should give me the same results as the old stuff. Should I be suspec=
>t?
>Cher Hoffman, who just spent 3 days preparing glaze line samples with the=
> new
>rutile, trying to get a "pretty pink" glaze for my Mom (if it's not pink,
>it's not pretty...she doesn't "get" the beauty of shino)
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Edouard Bastarache on sun 21 jul 02
Hello all,
"The definition of rutile allows for certain percentages of iron with the
TiO2 - something like up to 10% iron (I don't know the exact amount) If the
titanium has more than the maximum amount I think it them must be called
illmanite - I don't know where I got this information and I'm not sure I'm
even correct - perhaps others can enlighten us.
RR"
Different natural ilmenite ores have TiO2
concentrations ranging from about 30% up to 65% but,
never as high as in the different rutiles sold to potters.
QIT-Fer et Titane owns the world's largest ilmenite
deposit and it is located at Lac Tio in northeastern
Quebec, 1,000 miles from here.
The ore is shipped to Tracy (here) where it is processed into
titanium dioxide slags, synthetic rutile, iron pigs, steel billets,
different metallic powders and steel autoparts.
The TiO2 concentration of this ore is in the vicinity
of 27% while there is a mine in Madacascar where
it is close to 65%.
Here is an analysis:
SiO2 10.54
Al2O3 6.70
Fe2O3 32.72
TiO2 25.69
CaO 2.06
MgO 3.76
FeO 12.7
Imputities 5.66
Total 100
So, I would prefer to call them "iron-rich rutile".
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
iandol on sun 21 jul 02
I have samples of mine run Rutile which are transparent pink crystals, =
weighing to about four carats.
Dana tells us that depending on the source it is possible for =
considerable substitution where both Ferric and Ferrous ions ions =
replace Titanium, upwards of 10 per cent. Other elements may also be =
present. Also, since Rutile may occur associated with Ilmenite in "Black =
Sands" there may be contamination from this source.
So it might be a wise precaution to replace the natural mineral with =
refined Titanium oxide if there is any doubt.
One additional point. Rutile is a refractory material and it may require =
a longer period in the kiln to ensure that it is taken into solution =
before cooling starts, especially if it is being used for it's effects =
when fired at cone 6. If these things do not dissolve they cannot make a =
contribution to the anticipated aesthetic effects.
Perhaps it is a mistake to assume that getting to temperature or =
watching a cone bend to a certain degree is enough to ensure a mature =
glaze which conforms to our expectations. But it seems to me that =
Solubility is a factor which is not taken into account when designing =
glazes. There are a lot of assumptions which which go unquestioned or =
are taken for granted as being facts in published glaze theory. We are =
drawn into believing that materials we call fluxes will make a glaze =
recipe melt and the more of them we put in the better the melting =
properties. This is not necessarily true.
Best regards,
Ivor Lewis.
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