Lyn Packer on wed 10 sep 97
Hi Everyone, As I only got one reply from my inquiry regarding using rutile
in glazes, sent to the group a week ago, I thought that maybe someone out
there who had the knowledge, and had a bit of experience using this oxide,
would rather write to me personally. So as I didn't put my address on my
last message, have done so this time. In case you have deleted my message,
here is a quick summary of it again. Please bear with me. I am looking to
hear from anyone who has had experience using the different strength
rutiles in glazes. I have read what the books have to say about it, but I'm
sure there is more to know. Is there a limit to the amount of rutile you
can put in a glaze? If I added less would I get more colour? The glaze I am
experimenting with has 8% in it. My first test was lovely - blue speckled
with greens and pink coming through, cream where thick, and tan where thin.
It's a cone 9-10 glaze and I'm using it on a white stoneware body. When I
made up a 2nd test, the colour came out a fine speckled salmon pink with
just a hint of blue. I realise since, that I used a darker rutile. So maybe
that was what changed the colour. I'll be doing another test with the
rutile that I used originally. See what happens. Anyway, sorry about the
LONG summary.
Hopefully I may hear from you, personally if you prefer. Thanks in
ANTICIPATION!!
Lyn in beautiful N.Z., where the lambs are
froliking and the blossom is blossoming.
lyn.packer@clear.net.nz
Richard Aerni on thu 11 sep 97
Lyn,
Perhaps the reason you got so few responses is that rutile is a highly
variable material and how much or what kind to use is really rather a
matter of personal preference, or trial and error.
Rutile is an impure form of titanium dioxide, which can have between 92%
to 95% titania in it. The most common impurity is iron, though it can
also contain tantalum, niobium, chromium and tin. It comes in granular
form, ceramic grade, and dark rutile. The granular rutile imparts a
speckled look to a clay body or glaze (though it will not stay in glaze
suspension easily). The dark rutile and the ceramic rutile are the same
material, I've been told, with the difference being the ceramic rutile
has been calcined. I'm not sure why that would make a difference in the
final result, but in my tests it does, and I personally use the ceramic
grade in my glazes.
I have used glazes that use 8% rutile in them, and they tend to be rather
erratic and prone to pinholing. I most often used them over or under
other glazes, and in one particular case, with a celadon type glaze over
a base slip, I often ended up with amber tones, purples, blues and deeper
browns all on the same pot. So one test does not tell you all that much.
I would go for repeated tests on pots, not tiles, in different firings
and in different parts of the kiln, using the same sample of rutile.
This may actually give you some useful information that might enable you
to repeat your earlier results.
I won't go through all of my experiences with the material, but it seems
to me to be one of those that take you to heaven and then put you through
hell.
Good luck,
Richard Aerni
Lyn Packer wrote:
>
> ----------------------------Original message----------------------------
> Hi Everyone, As I only got one reply from my inquiry regarding using rutile
> in glazes, sent to the group a week ago, I thought that maybe someone out
> there who had the knowledge, and had a bit of experience using this oxide,
> would rather write to me personally. So as I didn't put my address on my
> last message, have done so this time. In case you have deleted my message,
> here is a quick summary of it again. Please bear with me. I am looking to
> hear from anyone who has had experience using the different strength
> rutiles in glazes. I have read what the books have to say about it, but I'm
> sure there is more to know. Is there a limit to the amount of rutile you
> can put in a glaze? If I added less would I get more colour? The glaze I am
> experimenting with has 8% in it. My first test was lovely - blue speckled
> with greens and pink coming through, cream where thick, and tan where thin.
> It's a cone 9-10 glaze and I'm using it on a white stoneware body. When I
> made up a 2nd test, the colour came out a fine speckled salmon pink with
> just a hint of blue. I realise since, that I used a darker rutile. So maybe
> that was what changed the colour. I'll be doing another test with the
> rutile that I used originally. See what happens. Anyway, sorry about the
> LONG summary.
> Hopefully I may hear from you, personally if you prefer. Thanks in
> ANTICIPATION!!
>
> Lyn in beautiful N.Z., where the lambs are
> froliking and the blossom is blossoming.
> lyn.packer@clear.net.nz
David Hendley on fri 12 sep 97
Lyn,
I agree with everything Richard had to say about rutile.
It's pretty unpredictable, but that's what makes it so much fun.
Any amount over 6-8 % will definitely increse the liklihood of pinhole
problems.
Do some line blends and you will be amazed at the difference even 1/2 %
will make.
For a good example look at my web page. Click on "pots", and the first
picture is of three bowls.
They are all the same base glaze.
The blue one has 3% rutile in the glaze, the white one 7%.
Totally different color and look.
Also, high rutile glazes seem to be sensitive to slight differences in
firing temperatures.
If overfired the tiny white crystsals space farther apart and a watery blue
shows up.
Do lots of tests!
David Hendley
Maydelle, Texas
See David Hendley's Pottery Page at
http://www.sosis.com/hendley/david/
Timothy Sullivan on mon 23 jul 01
I've looked at the archives, books, and a variety of web sites, and I'm still
kind of stumped over the color variations that rutile glazes produce. Even
with a single glaze I seem to get huge differences in color and surface
depending upon thickness and from firing to firing. Can anyone please help
me understand how a rutile glaze can be a beautiful lavender glossy glaze in
one firing and a boring satin tan in the next? What are the factors
(chemical and kiln) that affect rutile color variations? Is rutile's color
flux dependent, i.e., one color in a high CaO glaze and another with high
Na2O? Is the color impacted by the amount of alumina present, and/or the
Si:Al ratio? And does rutile's color change with atmosphere?
Thanks in advance for the info.
Tim (frustrated in Atlanta)
Ian Currie on tue 24 jul 01
Hi Tim
You are asking the right questions, which is half the battle! I often think
of titanium dioxide and rutile (titanium dioxide with some iron oxide) as
ceramic spices... they can add interest to an otherwise uninteresting glaze.
The main factor is the titanate crystals that it produces. These often matt
the glaze and also opacify it. Depending on the size of the opacifying
particles (the titanate crystals) you might also get good opalescence.
(This is particularly so in high silica/low alumina glazes.) When this gets
working you will find thickness is important - it always is with
opalescence. Similarly, clay body (especially presence or absence of iron
oxide) is important. Similarly cone number is important... and reducing or
oxidizing especially if using an iron-y clay.
As the glaze moves from opaque (e.g.tan) to opalescent (e.g. lavender), the
surface will become more shiny.
Often glazes that are otherwise a plain colour will break up into
interesting textures with rutile additon. I guess this is how the
needle-like titanate crystals affect the glaze. Anyway it is a crystal
thing and therefore rate of cooling will affect it. Slower cooling will
give more effect.
And certainly the oxides present in the base glaze (flux, alumina and
silica) and their proportions are very important.. If you have access to my
book "Revealing Glazes - Using the Grid Method", you will find some good
illustrations of partial or complete grid tiles that show some of these
effects in the colour plates on pages 87, 89 and 91. I suspect your
lavender gloss/satin tan problem is simply temperature. (Put some cones
near a sample to see what cone number is actually achieved.) Compare photos
F and G on page 89 of my book to show exactly this phenomenon.
Also if you can get hold of a copy of Hamer and Hamer's "Potters'
Dictionary of Materials and Techniques" read up on "rutile" and "titania".
Hope this is some help
Regards
Ian
http://ian.currie.to/
-----Original Message-----
From: Timothy Sullivan
To: CLAYART@LSV.CERAMICS.ORG
Date: Tuesday, 24 July 2001 1:31
Subject: Rutile again
I've looked at the archives, books, and a variety of web sites, and I'm
still
kind of stumped over the color variations that rutile glazes produce. Even
with a single glaze I seem to get huge differences in color and surface
depending upon thickness and from firing to firing. Can anyone please help
me understand how a rutile glaze can be a beautiful lavender glossy glaze in
one firing and a boring satin tan in the next? What are the factors
(chemical and kiln) that affect rutile color variations? Is rutile's color
flux dependent, i.e., one color in a high CaO glaze and another with high
Na2O? Is the color impacted by the amount of alumina present, and/or the
Si:Al ratio? And does rutile's color change with atmosphere?
Thanks in advance for the info.
Tim (frustrated in Atlanta)
Rick Hugel on tue 24 jul 01
I use rutile in a "Rutile Blue" glaze. I think I got it off Cayart. All
my firings are reduction so I can't say anything about oxidization, but I
consistently get a kind of lightly speckled blue. One thing I have
noticed is that the color is dependent on the clay I use. A very fine buff
clay with smooth walls and flat surfaces comes out very pale(almost white),
but if ridges/impressions are present blue dominates where glaze pools. On
the other hand, when used with sandy heavy iron bearing clay, the result is
outstanding and with ridges/impressions and one or two other things I do
the end product doesn't stay on the shelf too long.
Not much, but hope it helps
Rick
>I've looked at the archives, books, and a variety of web sites, and I'm still
>kind of stumped over the color variations that rutile glazes produce. Even
>with a single glaze I seem to get huge differences in color and surface
>depending upon thickness and from firing to firing. Can anyone please help
>me understand how a rutile glaze can be a beautiful lavender glossy glaze in
>one firing and a boring satin tan in the next? What are the factors
>(chemical and kiln) that affect rutile color variations? Is rutile's color
>flux dependent, i.e., one color in a high CaO glaze and another with high
>Na2O? Is the color impacted by the amount of alumina present, and/or the
>Si:Al ratio? And does rutile's color change with atmosphere?
>Thanks in advance for the info.
>Tim (frustrated in Atlanta)
>
>______________________________________________________________________________
>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.
Marvpots@AOL.COM on tue 24 jul 01
Hi Tim:
I recently, and for the first time, had a similar experience with rutile and
in the same firing!
I'll therefore be very interested in any replies you get.
Marvin Flowerman
marvpots@aol.com
Marvpots@AOL.COM on tue 24 jul 01
Re: Comments from Ian Currie:
I experienced what Tim describes in a recent cone 10 reduction firing and
that is what is puzzling to me, particularly when I achieved good reduction
characteristics on most of the other pieces in the kiln. I have been using
my rutile glaze for some time with excellent results in many previous firings
as to color, texture, etc. and this is the first time I experienced this
tan/matte result both inside and outside pieces.
Any further thoughts from you or others would be greatly appreciated.
Marvin Flowerman
Marvpots@aol.com
Tom Wirt/Betsy Price on thu 26 jul 01
Tim...
We've used a Rutile blue for years as you've probably discovered in
the archives...and over the years we've found this to be a notoriously
fickle glaze. We started with a recipe named moonlight from the John
Conrad Glaze Book. A couple of years ago, during an especially
troublesome time with crawling and pinholing, Ron Roy reformulated it
for us getting most of the Gerstley out...still keeping the denim blue
as the basic resulting color.
As you've discovered, thickness of application, firing cycle and
whatever dramatically affect results. Also, this glaze needs to be
deflocculated (we use Darvan 7 at Ron's advice) in order to keep the
amount of water down. You need to be measuring Specific density of
the glaze slop to be able to stand any chance of a consistent color.
Do NOT use a hydrometer for this...measure weight/volume.
Firing affects the color result, but we have found consistent
patterns. The deep lavender is one result, a light blue (where the
glaze is thick) is another. We never get baby poop brown
anymore....for us that was mostly an issue of applying too thin. The
electric blue seems to come up mostly in oxidation and when the glaze
is fired to about cone 9-1/2.
Recently Ron and Tom Buck have again been helping us through a spate
of pinholing and cratering. They have noted that the glaze as we were
using it is seriously short of silica, and this possibly has caused
some of the problems.
Tom reformulated it 3 ways for us getting rid of the gerstly and for
the most part the rutile. I have asked his permission to post these
recipes as well as a bit of discussion he gave as to why he's using
the ingredients (most notably Wollastonite) that he is. These
recipes, if used should be credited to Tom. The discussion is his
copyright.
While I don't know why the blues appear in these glazes, and haven't
seen any knowledgeable discussion of it in 8 years of ClayArt (only
speculation), they do seem to be crystal dependent floating in a clear
matrix. And the firing cycle and application will definitely influence
these. We often saw the electric blue show up on refires to fix
pinholes or crawls.
If you're going to go down the siren path of the rutile blues, be
prepared for variation...it seems to be an inherent part of the glaze
type.
(from Tom Buck)Folks:
when you experience pinholing pitting, the first step is to look
at your glaze recipe. If it contains materials that outgas
substantially
at high cones, then you should substitute via glzcalc for these
materials.
Bad actors are: dolomite, whiting (calcite/limestone), gerstley borate
(and its newer versions that are combos of ulexite and colemanite from
offshore mostly). e.g., Whiting is 56%w CaO and 44%w CO2, and the
decomposition range is above 900 oC (1650 oF); dolomite or CaCO3.MgCO3
behaves in a similar fashion. And the sodium/calcium borate materials
(ulexite, colemanite, gerstley borate) offgas at least 25%w at
lowercones
then when high cones are reached the B2O3 content starts to boil.
Most C10 glazes should not contain B2O3 at much above 0.1 moles,
in fact, B2O3 should be excluded. But if you need to use it, then
accessing it via a frit has merit because it will start to sinter/melt
at mid cones, and become tied up chemically and not thereby be free to
boil as C10 approaches.
So, if a glaze has CaO/MgO + B2O3 in it, I have found that better
glazes result using wollastonite/talc (they have low outgassing) and a
borate frit
bye for now. peace. Tom B.
(from Tom Buck)
while the new mixes do not give the mottling effect ("denim") that
you want, they do confirm that your problem lies in the combination of
Cornwall Stone and Rutile (plus perhaps the Gerstley Borate you have
on
hand). The pinholes come from high-temperature outgassing in a too-
viscous melt.
You say you want the denim effect. Well, the "floating blue"
effect is, as far as I know, only available from rutile. But you may
be
able to get that look by adding some copper oxide, 0.25%w, either
black
oxide or red oxide ...if you use red oxide, you will need a drop or
two of
detergent (dishpan is fine) to counteract the coating on the
particles.
The question remains: are you satisfied that the problem is glaze
based, not claybody based?
til later. peace. Tom B.
Tom Buck Blue 1
My take on Moonlight is similar...too many components, difficult
to blend/disperse well. Which could be the source of its charm, and
the
pinholes. I note the low level of SiO2 in this mix, and think that
some
uneven melting might cause the pinholes. I offer this change:
18 G-200 fs
18 FF 3124
17 Kona F-4 fs
10 Wollastonite
2 Talc
12 Old Mine #4 (or equal)
23 Flint (fine mesh)
plus 3%w Rutile; 1%w Ilmenite; 0.3%w Cobalt Carbonate Basic
This mix takes the gloss up a bit (R=9.6) and lowers the Expansion
(=6.9x10-6). This glaze would have very low outgassing.
>
Tom Buck Blue 2, revised, low outgassing C10R
>
> 18 FF 3134 CaO 0.58 Al2O3 0.45 SiO2 4.26
> 18 G200 fs MgO 0.08 B2O3 0.23 TiO2 0.14
> 17 Kona F-4 K2O 0.11 Fe2O3 0.01
> 9.5 Wollast. Na2O 0.23
> 2.5 Talc Ratio SiO2/Al2O3 = 9.5
> 10 OM#4 Expansion = 7.2x10-6
> 20 Flint
>
> add: 2.8 TiO2 (anatase or paint pigment)
> 0.2 Iron ox. red or black
> 0.5 Ilmenite, coarse\granular
> 0.3 Cobalt carbonate basic
>
>
> Tom Buck Blue 3, revised, low outgassing C10R
>
> 21 G200 fs CaO 0.57 Al2O3 0.48 SiO2 4.44
> 20 Kona F-4 MgO 0.08 B2O3 0.15 TiO2 0.15
> 19 FF3124 K2O 0.13 Fe2O3 0.01
> 11 Wollast. Na2O 0.22
> 2.5 Talc Ratio= 9.2 Expn= 7.2x10-6
> 8.5 OM#4
> 18 Flint
>
> add: 2.9 TiO2 (as above)
> 0.2 Iron ox red or black
> 0.5 Ilmenite, coarse\granular
> 0.3 Cobalt carbonate basic
>
Ron Roy Moonlight - 4 % gerstley. (Revision from Conrad Moonlight)
================
CORNWALL STONE...... 27.00 25.89%
G-200 FELDSPAR G200. 15.50 14.86%
Gerstley Borate............ 4.00 3.84%
F12 (FERRO3134)..... 13.00 12.46%
DOLOMITE............ 2.00 1.92%
SILICA.............. 12.00 11.51%
WHITING............. 6.50 6.23%
OM #4 BALL CLAY..... 18.99 18.21%
RUTILE.............. 3.00 2.88%
*Illmenite........... 2.00 1.92%
*cobalt carb......... 0.30 0.29%
========
104.29
CaO 0.60* 8.66%
MgO 0.06* 0.59%
K2O 0.13* 3.19%
Na2O 0.21* 3.30%
TiO2 0.17 3.40%
ZrO2 0.00 0.03%
Al2O3 0.51 13.26%
B2O3 0.30 5.37%
SiO2 4.03 61.92%
Fe2O3 0.01 0.29%
Cost/kg 1.78
Si:Al 7.92
SiB:Al 8.52
Expan 7.32
----- Original Message -----
From: "Timothy Sullivan"
Subject: Rutile again
I'm still
> kind of stumped over the color variations that rutile glazes
produce. Even
> with a single glaze I seem to get huge differences in color and
surface
> depending upon thickness and from firing to firing.
Richard Aerni on tue 16 sep 03
another rutile post from long ago...
Lyn,
Perhaps the reason you got so few responses is that rutile is a highly
variable material and how much or what kind to use is really rather a
matter of personal preference, or trial and error.
Rutile is an impure form of titanium dioxide, which can have between 92%
to 95% titania in it. The most common impurity is iron, though it can
also contain tantalum, niobium, chromium and tin. It comes in granular
form, ceramic grade, and dark rutile. The granular rutile imparts a
speckled look to a clay body or glaze (though it will not stay in glaze
suspension easily). The dark rutile and the ceramic rutile are the same
material, I've been told, with the difference being the ceramic rutile
has been calcined. I'm not sure why that would make a difference in the
final result, but in my tests it does, and I personally use the ceramic
grade in my glazes.
I have used glazes that use 8% rutile in them, and they tend to be rather
erratic and prone to pinholing. I most often used them over or under
other glazes, and in one particular case, with a celadon type glaze over
a base slip, I often ended up with amber tones, purples, blues and deeper
browns all on the same pot. So one test does not tell you all that much.
I would go for repeated tests on pots, not tiles, in different firings
and in different parts of the kiln, using the same sample of rutile.
This may actually give you some useful information that might enable you
to repeat your earlier results.
I won't go through all of my experiences with the material, but it seems
to me to be one of those that take you to heaven and then put you through
hell.
Good luck,
Richard Aerni
Lyn Packer wrote:
>
> ----------------------------Original message----------------------------
> Hi Everyone, As I only got one reply from my inquiry regarding using
rutile
> in glazes, sent to the group a week ago, I thought that maybe someone out
> there who had the knowledge, and had a bit of experience using this oxide,
> would rather write to me personally. So as I didn't put my address on my
> last message, have done so this time. In case you have deleted my message,
> here is a quick summary of it again. Please bear with me. I am looking to
> hear from anyone who has had experience using the different strength
> rutiles in glazes. I have read what the books have to say about it, but
I'm
> sure there is more to know. Is there a limit to the amount of rutile you
> can put in a glaze? If I added less would I get more colour? The glaze I
am
> experimenting with has 8% in it. My first test was lovely - blue speckled
> with greens and pink coming through, cream where thick, and tan where
thin.
> It's a cone 9-10 glaze and I'm using it on a white stoneware body. When I
> made up a 2nd test, the colour came out a fine speckled salmon pink with
> just a hint of blue. I realise since, that I used a darker rutile. So
maybe
> that was what changed the colour. I'll be doing another test with the
> rutile that I used originally. See what happens. Anyway, sorry about the
> LONG summary.
> Hopefully I may hear from you, personally if you prefer. Thanks in
> ANTICIPATION!!
>
> Lyn in beautiful N.Z., where the lambs are
> froliking and the blossom is blossoming.
Steve Slatin on sun 28 sep 08
Marian --
Granular rutile and dark rutile may cause
pinholing with some glazes. Reasonable
amounts (6% and under) of the ceramic grade
don't seem to do so, at least in my glazes.
Too thick an application of a rutile/
gerstley wash will make a rough surface, and
put bubbles on the surface of your glaze.
A thin application can look like a fireworks
display ...
So like almost everything else in ceramics,
it all depends. I'm sure there are a variety
of satisfactory results with granular, dark,
and ceramic grade rutile. A treatment with
dark or granular rutile over a glaze that
is impervious to flaws like pinholing won't
probably be a problem. If it is, maybe
changing your firing ramps or adding a hold or
increasing the length of the cooling time
will resolve any flaws. If not, and your
glaze isn't runny at all, you might find
that there won't be a pinholing problem
if you reduce your alumina level just slightly.
Or maybe your aesthetic admits of rough surfaces in
your work, in which case a little pinholing or
bubbling wouldn't be a problem anyway ...
Steve Slatin
--- On Sun, 9/28/08, Marian wrote:
> And this brings up something I've wondered about... dark
> or light
> rutile? Which is appropriate with the Magic Wash recipe
> below? When
> rutile is used in a glaze recipe is it normally dark
> rutile? In what
> applications would each of them be appropriate?
>
> Mel, are there any particular kinds of glazes that you
> wouldn't use
> the Magic Wash on? That is... for aesthetic reasons and
> not
> necessarily because a glaze runs?
>
> Sorry for all the questions. This is similar to something
> I learned
> in a class as magic lip goo which we used to address the
> lip of pots.
> But we added some iron oxide to it.
>
>
mel jacobson on sun 28 sep 08
rutile is as close to magic as you can get in
glaze. it turns blue, red, gold, tan, yellow...depending!
it has range, excitement, and adventure.
and, as carol knighten points out in a private
email....even a gridder can make it work perfectly with
good science.
and those of us that have used it for many years understand...
it can be used in a very stable, non runny glaze with tremendous
success. AND IT DOES MAKE THE SURFACE DANCE.
MAGIC WASH, used over any glaze.
one cup of your best glaze/clear/white.
big tablespoon of rutile.
some will add a spoon of sodium silicate. i don't.
or some will add some gertsley...i do often.
use it as a surface paint.
adjust the formula to taste. it is a theory, not a recipe.
mel
from minnetonka:
website http://www.visi.com/~melpots/
clayart site:
http://www.visi.com/~melpots/clayart.html
Mary Starosta on sun 28 sep 08
Mel or anyone, why Gertsley and not Manganese Dioxide? Rutile is a Flux
Right? Gerstley is both Oxide and Flux Right? But Manganese Dioxide becomes
MnO which becomes a flux after 1080C firing or that would be 1976F or a cone
03 and 1/2ish.
Notes http://ceramic-materials.com/cermat/education/155.html
Above 1080C, half of the oxygen disassociates to produce MnO, a flux which
immediately reacts with silica to produce violet colors in the absence of
alumina, browns in its presence. Thus if it is being used in glazes fired
below 1080C it should be considered as MnO2, if above it should be taken as
81.5 MnO and 18.5 LOI.
Glazes and bodies that employ manganese dioxide below its conversion
temperature of 1080C (to MnO) will fire black and purple colors. In glazes,
it will behave in a refractory manner, stiffening the melt.
"rutile is as close to magic as you can get in
glaze. it turns blue, red, gold, tan, yellow...depending!"
Why not go for Violet as well?
Mary Starosta
Colorado Potter
>
> MAGIC WASH, used over any glaze.becomes MnO which becomes a flux after
> 1080C firing.
>
> one cup of your best glaze/clear/white.
> big tablespoon of rutile.
> some will add a spoon of sodium silicate. i don't.
> or some will add some gertsley...i do often.
>
> use it as a surface paint.
> adjust the formula to taste. it is a theory, not a recipe.
> mel
> from minnetonka:
> website http://www.visi.com/~melpots/
> clayart site:
> http://www.visi.com/~melpots/clayart.html
>
--
Mary Starosta
www.StarostaTeam.com
ReMax Alliance
mary@starostateam.com
720-271-7523
Marian on sun 28 sep 08
And this brings up something I've wondered about... dark or light
rutile? Which is appropriate with the Magic Wash recipe below? When
rutile is used in a glaze recipe is it normally dark rutile? In what
applications would each of them be appropriate?
Mel, are there any particular kinds of glazes that you wouldn't use
the Magic Wash on? That is... for aesthetic reasons and not
necessarily because a glaze runs?
Sorry for all the questions. This is similar to something I learned
in a class as magic lip goo which we used to address the lip of pots.
But we added some iron oxide to it.
--- In clayart@yahoogroups.com, mel jacobson wrote:
>
> rutile is as close to magic as you can get in
> glaze. it turns blue, red, gold, tan, yellow...depending!
>
> it has range, excitement, and adventure.
>
> and, as carol knighten points out in a private
> email....even a gridder can make it work perfectly with
> good science.
>
> and those of us that have used it for many years understand...
> it can be used in a very stable, non runny glaze with tremendous
> success. AND IT DOES MAKE THE SURFACE DANCE.
>
>
>
> MAGIC WASH, used over any glaze.
>
> one cup of your best glaze/clear/white.
> big tablespoon of rutile.
> some will add a spoon of sodium silicate. i don't.
> or some will add some gertsley...i do often.
>
> use it as a surface paint.
> adjust the formula to taste. it is a theory, not a recipe.
> mel
> from minnetonka:
> website http://www.visi.com/~melpots/
> clayart site:
> http://www.visi.com/~melpots/clayart.html
>
Ron Roy on wed 1 oct 08
Hi Mary,
Rutile is mostly TiO2 and is not a flux - in fact it is sometimes added to
crystalline glazes where it remains a crystal - giving other crystals a
place to start growing - it's called seeding.
Manganese is one of our more toxic materials - the dust and kiln fumes can
lead to serious problems. Know your materials. I'm not saying don't use it
- just understand what you have to do to protect yourself and others.
RR
>Mel or anyone, why Gertsley and not Manganese Dioxide? Rutile is a Flux
>Right? Gerstley is both Oxide and Flux Right? But Manganese Dioxide becomes
>MnO which becomes a flux after 1080C firing or that would be 1976F or a cone
>03 and 1/2ish.
>Notes http://ceramic-materials.com/cermat/education/155.html
>
>Above 1080C, half of the oxygen disassociates to produce MnO, a flux which
>immediately reacts with silica to produce violet colors in the absence of
>alumina, browns in its presence. Thus if it is being used in glazes fired
>below 1080C it should be considered as MnO2, if above it should be taken as
>81.5 MnO and 18.5 LOI.
>
>Glazes and bodies that employ manganese dioxide below its conversion
>temperature of 1080C (to MnO) will fire black and purple colors. In glazes,
>it will behave in a refractory manner, stiffening the melt.
>
>"rutile is as close to magic as you can get in
>glaze. it turns blue, red, gold, tan, yellow...depending!"
>
>Why not go for Violet as well?
>
>Mary Starosta
>Colorado Potter
>
>
>
>>
>> MAGIC WASH, used over any glaze.becomes MnO which becomes a flux after
>> 1080C firing.
>>
>> one cup of your best glaze/clear/white.
>> big tablespoon of rutile.
>> some will add a spoon of sodium silicate. i don't.
>> or some will add some gertsley...i do often.
>>
>> use it as a surface paint.
>> adjust the formula to taste. it is a theory, not a recipe.
>> mel
>> from minnetonka:
>> website http://www.visi.com/~melpots/
>> clayart site:
>> http://www.visi.com/~melpots/clayart.html
>>
>
>
>
>--
>Mary Starosta
>www.StarostaTeam.com
>ReMax Alliance
>mary@starostateam.com
>720-271-7523
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Mary Starosta on wed 1 oct 08
Thanks "*Light bulb Moment:"* Duh
Mary
On Wed, Oct 1, 2008 at 8:09 PM, Ron Roy wrote:
> Hi Mary,
>
> *Rutile is mostly TiO2 and is not a flux* - in fact it is sometimes added
> to
> crystalline glazes where it remains a crystal - giving other crystals a
> place to start growing - it's called seeding.
>
> Manganese is one of our more toxic materials - the dust and kiln fumes can
> lead to serious problems. Know your materials. I'm not saying don't use it
> - just understand what you have to do to protect yourself and others.
>
> RR
>
> >"rutile is as close to magic as you can get in
> >glaze. it turns blue, red, gold, tan, yellow...depending!"
> >
> >Why not go for Violet as well?
> >
> >Mary Starosta
> >Colorado Potter
>
> *>> MAGIC WASH, used over any glaze.becomes MnO which becomes a flux after
> >> 1080C firing.
> * >>
> >> one cup of your best glaze/clear/white.
> >> big tablespoon of rutile.
> >> some will add a spoon of sodium silicate. i don't.
> >> or some will add some gertsley...i do often.
> >>
> >> use it as a surface paint.
> >> adjust the formula to taste. it is a theory, not a recipe.
> >> mel
> >> from minnetonka:
> >> website http://www.visi.com/~melpots/
> >> clayart site:
> >> http://www.visi.com/~melpots/clayart.html
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
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