Christine Fennimore on tue 17 sep 96
Bob:
Here's a couple that I have tried and added to my regulars (both come from
clayart folks).
Moonlight: (Cone 10-Reduction)
Cornwall Stone 63.8
Gerstley Borate 14.3
Flint 7.6
Whiting 7.6
EPK 4.8
Zinc Oxide 1.9
Rutile 3.2
Powdered Ilmenite 2.0
Long Beach Blue (Cone 10 - Reduction)
Whiting 19.49
Custer 63.55
EPK 16.96
Cobalt Carb .85
Rutile 4.0
If you are looking for a shiny glaze try the Moonlight. If you want a soft
matt blue, try the Long Beach Blue. The Long Beach is terrible if applied
too thin. The Moonlight will run if applied to thick.
Good luck.
--------------------------------------
Chris Fennimore
Native American Rights Fund
Boulder, CO
Joyce Lee on sun 8 feb 98
Are the two rutile blues posted to Clayart apt to run? I've tried
several rutiles but when they developed into a gorgeous blue glaze, they
also ran terribly...or I should say they ran very well, indeed. Do
these two run all over the shelves, also, and, if so, does anybody know
how that might be corrected? Help from anybody would be appreciated.
Thank you.
Joyce
In the Mojave...grey skies again...incredible.
Mo and Les Beardsley on mon 9 feb 98
Joyce Lee wrote:
>
> ----------------------------Original message----------------------------
> Are the two rutile blues posted to Clayart apt to run? I've tried
> several rutiles but when they developed into a gorgeous blue glaze, they
> also ran terribly...or I should say they ran very well, indeed. Do
> these two run all over the shelves, also, and, if so, does anybody know
> how that might be corrected? Help from anybody would be appreciated.
> Thank you.
>
> Joyce
> In the Mojave...grey skies again...incredible.
Dear Joyce...
Rutile Blue II at cone 7 is a nice cream
at cone 7 1/2 it is breaking blue
at cone 8 it is blue
at cone 8.5 ( cone 9 down half) it is a good blue
at cone 9 it starts to run
at cone 10 it is off the pot.
This is on a constant white body such as porcelin (pardon the spelling)
in a down draft kiln running for a reasonable time...not too many extra
hours...such as 6-7 hours.
Regards
Les Beardsley
John & Anne Worner on fri 25 sep 98
Hi there!
I am jumping in with both feet here - so if I am way off course, please,
Tony or Ron or someone with years more experience with glaze chemistry -
correct me. I'm pretty new at this, but I am seriously hooked!
A friend and I have recently been discussing how to get the rutile
blues. I recognize your original formula as Glossman Rutile - the
formula we have has an added 5% of copper carbonate - probably because
getting blues from rutile are so hard to control.
Anyway, you did stiffen your melt considerably in your revision, maybe a
bit too much! However, you drastically lowered your calcium content. I
have noticed that rutile blues have high calcia in their formulas.
I have seen the original Glossman's fired in reduction on porcelain and
it
is a gorgeous glaze. You are right though: it runs and it also crazes
so you
would want to get it amended for that very reason.
It will be interesting to read the responses to this post. If you get
anything
interesting off-list, let us all know. 'kay.
I have attempted a revision and if you do test this before we get around
to it here, please let me know the results - and the Clayart list too.
Anne Worner
Spring, TX - praying Georges doesn't head this way!
1.Your original formula:
30.00 CUSTER FELDSPAR
15.80 DOLOMITE
11.10 WHITING
16.80 EPK KAOLIN
26.30 FLINT
8.00 RUTILE
CaO 0.62* 13.09%
MgO 0.25* 3.77%
K2O 0.10* 3.40%
Na2O 0.04* 0.96%
TiO2 0.29 8.62%
ZrO2 0.00 0.08%
Al2O3 0.32 12.54%
P2O5 0.00 0.04%
SiO2 2.52 57.33%
Fe2O3 0.00 0.18%
Cost/kg 0.50
Si:Al 7.76
SiB:Al 7.76
Expan 7.59
2. Your revised formula:
60.00 CUSTER FELDSPAR
10.00 DOLOMITE
20.00 EPK KAOLIN
10.00 TALC
8.00 RUTILE
CaO 0.20* 3.25%
MgO 0.47* 5.53%
K2O 0.23* 6.21%
Na2O 0.10* 1.75%
TiO2 0.34 7.93%
ZrO2 0.00 0.07%
Al2O3 0.61 17.91%
P2O5 0.00 0.05%
SiO2 3.28 57.06%
Fe2O3 0.00 0.23%
Cost/kg 0.50
Si:Al 5.41
SiB:Al 5.41
Expan 7.66
Revision of original Glossman Rutile (Green) ^8-10
14.55 DOLOMITE
27.62 CUSTER FELDSPAR
10.87 WOLLASTONITE
23.02 EPK KAOLIN
23.94 FLINT
8.00 RUTILE
5.00 *Copper Carbonate
CaO 0.60* 10.89%
MgO 0.26* 3.34%
K2O 0.10* 3.01%
Na2O 0.04* 0.84%
TiO2 0.32 8.23%
ZrO2 0.00 0.08%
Al2O3 0.43 14.04%
P2O5 0.00 0.06%
SiO2 3.05 59.23%
Fe2O3 0.01 0.28%
MnO 0.00* 0.01%
Cost/kg 0.61
Si:Al 7.16
SiB:Al 7.16
Expan 7.20
Tony Hansen on mon 28 sep 98
I'm pretty ignorant on this subject.
I've always gotten good rutile blues on both iron and buff bodies
so I never suspected the involvement of iron in making the blue.
I just assumed that fluid calcium rich glazes formed blue cystals
with rutile. However now that you mention it this does not work
with titanium. My rutile supply varies in iron content and come
to think of it so has the shade of my rutile blues.
One thing that has troubled many potters is the tencency of
fluid rutile blues to blister. Anyone know why?
--
T o n y H a n s e n thansen@digitalfire.com
Don't fight the dragon alone http://digitalfire.com
Calculation/Database Software for Ceramic Industry
Don MacDonald on tue 29 sep 98
While on the subject of Rutile Glazes, does anyone know why some rutile
glazes, usually the more matt variety, cause your pots to be full of
static cling for the first couple of days after they are unloaded from
the kiln? This is not a problem, just a curiousity, but I would love to
know why it happens. I have seen it occur with pieces coming out of
three different gas fired reduction kilns, the only common denominator
seems to be rutile.
June
Tony Hansen wrote:
>
> ----------------------------Original message----------------------------
> I'm pretty ignorant on this subject.
> I've always gotten good rutile blues on both iron and buff bodies
> so I never suspected the involvement of iron in making the blue.
> I just assumed that fluid calcium rich glazes formed blue cystals
> with rutile. However now that you mention it this does not work
> with titanium. My rutile supply varies in iron content and come
> to think of it so has the shade of my rutile blues.
>
> One thing that has troubled many potters is the tencency of
> fluid rutile blues to blister. Anyone know why?
>
> --
> T o n y H a n s e n thansen@digitalfire.com
> Don't fight the dragon alone http://digitalfire.com
> Calculation/Database Software for Ceramic Industry
Ron Roy on wed 30 sep 98
Hello the group - Peter Hamer has some difficulty posting to the list and
asked me to post this for him. If you have advice for him so that he can
post to ClatArt please contact him.
Ron,
I tried to post this contribution to the thread, but I never seem to
succeed for bit.list groups. I wonder if you could post it for me?
Peter Hamer pgh@nortel.co.uk
---------------------------------------
Re: The source of rutile blue????
A very good discussion of this is contained in a chapter on "Chun"
blues towards the back of ...
Staneware glazes: a systematic approach
Ian Currie
The effect occurs when the glaze composition lies just between that
for an opaque and transparent glaze. The blue colour is "optical"
(rather than a solution colour) and caused by small inclusions in
the glaze (bubbles? beads of phosphorus glass?).
Applying the main glaze over a red iron-rich one maximises the effect,
probably for several reasons. The red background makes the blue more
visible, and there are almost certainly efffects caused by the boundary
between the glazes. I'm uncertain if any boundary effect is
fundamentally different from that achievable in a single glaze; or
if it just gives a thin region of changing properties which maximises
the chance of the mix being right somewhere. Right almost certainly
requires the inclusions to be the right size relative to the wavelength
of light, so is quite critical -- and probably influenced by relatively
minor changes in the firing cycle.
BTW the chun effect can occur independently of other effects: copper
red plus chun gives copper flambe; adding a little cobalt gives an
additional solution blue effect (some people would regard this as
cheating).
Peter
Curries glaze test-tile experiments (detailed in his book) indicate
that chun effects can occur in a wide range of glaze types; but always
over a fairly small range of compositions.
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Tom Buck on thu 1 oct 98
Tony:
There follows an outline of one scenario that will account for
the blisters on your Rutile glazes.
Wherever a sizeable paint industry exists, there often will be
close-by a chemical plant processing either Ilmenite or Rutile ores
to make Titanium Dioxide, the paint industry's preferred pigment
for white coatings. (Other industries also use these materials).
In North America, 20+ years ago there were 15 plants making
TiO2 mostly from Ilmenite (perhaps two using Rutile ore). At some
point in Ilmenite conversion, Rutile is sometimes recovered
separately from TiO2. Ilmenite deposits were found widely in North
America whereas Rutile occurred only in Virgina and Quebec.
Ilmenite is a mineral with an analysis of approximately 62%
TiO2 and 26% Fe2O3 (but the iron acutally exists in the crystal as
repeating units of FeO). Although silica and alumina make up much
of the 10-12% gangue (unwanted material), it is likely the ore
could also contain fluorides, sulfides, carbonates and sulfates. If
ceramic grade Rutile is recovered from Ilmenite then some of these
impurities will also be in the Rutile but to a lesser extent since
Rutile (from Ilmenite) is typically 92% TiO2 and 2%+ Fe2O3 (as
FeO). However, some Rutile ore is also sold as such to other
industries, and it can contain up to 10% Fe2O3 and a corresponding
amount of gangue.
So, there likely are at least four sources of Rutile that
could be bought by potters, and each could have different
impurities. One should regard Rutile as "uncertain" in composition,
ie, another "gerstley borate" to puzzle potters.
If your Rutile contained some Cryolite (Na3AlF6) or Fluorspar
(CaF2) or Fluoro-silicates, then these minerals would account for
the blisters you are seeing on your Rutile glazes. Many fluorine
compounds do not begin to out-gas until quite high temperatures are
reached, somewhat above the 1000+ degrees Celsius of Limestone
(Whiting) and Dolomite. (The sulfur compounds would change and out-
gas at lower temperatures).
Your only recourse is to find Rutile from a different plant
and hope it has less Fluorine compounds as contaminants.
Good tests. Til later. Regards. Tom.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
On Mon, 28 Sep 1998, Tony Hansen wrote:
> ----------------------------Original message----------------------------
> I'm pretty ignorant on this subject.
> I've always gotten good rutile blues on both iron and buff bodies
> so I never suspected the involvement of iron in making the blue.
> I just assumed that fluid calcium rich glazes formed blue cystals
> with rutile. However now that you mention it this does not work
> with titanium. My rutile supply varies in iron content and come
> to think of it so has the shade of my rutile blues.
>
> One thing that has troubled many potters is the tencency of
> fluid rutile blues to blister. Anyone know why?
>
> --
> T o n y H a n s e n thansen@digitalfire.com
> Don't fight the dragon alone http://digitalfire.com
> Calculation/Database Software for Ceramic Industry
>
Paul Huel on fri 2 oct 98
------------------
Tony and Tom,
I am also experiencing some blisters in a glaze that I use 2=25 rutile
in, the blisters do not seem consistent, but they do seem to occur
near the top of the kiln where it may cool a little quicker, I also
notice that they are worse when I first mix up a batch of glaze. What
percent of rutile are you using Tony in the glazes that you are having
trouble with? Thanks Tom Buck for the info on rutile.
Paul
=3E----------------------------Original message----------------------------
=3ETony:
=3E There follows an outline of one scenario that will account for
=3Ethe blisters on your Rutile glazes.
=3E Wherever a sizeable paint industry exists, there often will be
=3Eclose-by a chemical plant processing either Ilmenite or Rutile ores
=3Eto make Titanium Dioxide, the paint industry's preferred pigment
=3Efor white coatings. (Other industries also use these materials).
=3E=3E ----------------------------Original =
message----------------------------
=3E=3E I'm pretty ignorant on this subject.
=3E=3E I've always gotten good rutile blues on both iron and buff bodies
=3E=3E so I never suspected the involvement of iron in making the blue.
=3E=3E I just assumed that fluid calcium rich glazes formed blue cystals
=3E=3E with rutile. However now that you mention it this does not work
=3E=3E with titanium. My rutile supply varies in iron content and come
=3E=3E to think of it so has the shade of my rutile blues.
=3E=3E
=3E=3E One thing that has troubled many potters is the tencency of
=3E=3E fluid rutile blues to blister. Anyone know why?
=3E=3E
=3E=3E --
=3E=3E T o n y H a n s e n thansen=40digitalfire.com
=3E=3E Don't fight the dragon alone http://digitalfire.com
=3E=3E Calculation/Database Software for Ceramic Industry
=3E=3E
Edouard Bastarache on fri 2 oct 98
Hello Tom,
i dont know where there is a Rutile mine in Quebec.
But there is an Ilmenite mine in northeastern Quebec at Havre St-Pierre,
the ore is shipped to Tracy where it is processed to :
1-titanium dioxide slag of different grades(different concentations of
TIO2),
2-iron pigs,
3-still billets,
4-steel auto parts(Quebec Metal Powders).
The name of the company is QIT-Fer et Titane.It is owned by Rio Tinto Zinc.
Two plants making titanium dioxide are also located in our region for
obvious reasons,
they supply many customers in eastern Canada and USA(paint and paper
companies etc.)
1-Kronos in Varennes,about 30 miles from Tracy
2-Tioxide of Canada in Tracy, Tioxide makes a grade of TiO2 that is called
"rutile".
By the way Kronos is in the process of buying Tioxide's plant in Tracy.
Later,
Edouard Bastarache
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
----------
> De : Tom Buck
> A : CLAYART@LSV.UKY.EDU
> Objet : Re: Rutile Blues
> Date : 1 octobre, 1998 10:07
>
> ----------------------------Original message----------------------------
> Tony:
> There follows an outline of one scenario that will account for
> the blisters on your Rutile glazes.
> Wherever a sizeable paint industry exists, there often will be
> close-by a chemical plant processing either Ilmenite or Rutile ores
> to make Titanium Dioxide, the paint industry's preferred pigment
> for white coatings. (Other industries also use these materials).
> In North America, 20+ years ago there were 15 plants making
> TiO2 mostly from Ilmenite (perhaps two using Rutile ore). At some
> point in Ilmenite conversion, Rutile is sometimes recovered
> separately from TiO2. Ilmenite deposits were found widely in North
> America whereas Rutile occurred only in Virgina and Quebec.
> Ilmenite is a mineral with an analysis of approximately 62%
> TiO2 and 26% Fe2O3 (but the iron acutally exists in the crystal as
> repeating units of FeO). Although silica and alumina make up much
> of the 10-12% gangue (unwanted material), it is likely the ore
> could also contain fluorides, sulfides, carbonates and sulfates. If
> ceramic grade Rutile is recovered from Ilmenite then some of these
> impurities will also be in the Rutile but to a lesser extent since
> Rutile (from Ilmenite) is typically 92% TiO2 and 2%+ Fe2O3 (as
> FeO). However, some Rutile ore is also sold as such to other
> industries, and it can contain up to 10% Fe2O3 and a corresponding
> amount of gangue.
> So, there likely are at least four sources of Rutile that
> could be bought by potters, and each could have different
> impurities. One should regard Rutile as "uncertain" in composition,
> ie, another "gerstley borate" to puzzle potters.
> If your Rutile contained some Cryolite (Na3AlF6) or Fluorspar
> (CaF2) or Fluoro-silicates, then these minerals would account for
> the blisters you are seeing on your Rutile glazes. Many fluorine
> compounds do not begin to out-gas until quite high temperatures are
> reached, somewhat above the 1000+ degrees Celsius of Limestone
> (Whiting) and Dolomite. (The sulfur compounds would change and out-
> gas at lower temperatures).
> Your only recourse is to find Rutile from a different plant
> and hope it has less Fluorine compounds as contaminants.
> Good tests. Til later. Regards. Tom.
>
> Tom Buck ) tel: 905-389-2339
> & snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
> (westend Lake Ontario, province of Ontario, Canada).
>
> On Mon, 28 Sep 1998, Tony Hansen wrote:
>
> > ----------------------------Original
message----------------------------
> > I'm pretty ignorant on this subject.
> > I've always gotten good rutile blues on both iron and buff bodies
> > so I never suspected the involvement of iron in making the blue.
> > I just assumed that fluid calcium rich glazes formed blue cystals
> > with rutile. However now that you mention it this does not work
> > with titanium. My rutile supply varies in iron content and come
> > to think of it so has the shade of my rutile blues.
> >
> > One thing that has troubled many potters is the tencency of
> > fluid rutile blues to blister. Anyone know why?
> >
> > --
> > T o n y H a n s e n thansen@digitalfire.com
> > Don't fight the dragon alone http://digitalfire.com
> > Calculation/Database Software for Ceramic Industry
> >
Ron Roy on sat 3 oct 98
Hi Gang,
When I read Tom's disertation on the possible reasons for rutile producing
bubbles it occured to me that firing it up to glaze temp might be a way of
taming it - any reasons not to try this?
If you are tempted to try it - just do a small amount first - I think I am
right in assuming it will not melt - right?
Come to think of it maybe even a bisque firing might be enough - best to
not pile it up but rather a thin layer on a refractory plate
> If your Rutile contained some Cryolite (Na3AlF6) or Fluorspar
>(CaF2) or Fluoro-silicates, then these minerals would account for
>the blisters you are seeing on your Rutile glazes. Many fluorine
>compounds do not begin to out-gas until quite high temperatures are
>reached, somewhat above the 1000+ degrees Celsius of Limestone
>(Whiting) and Dolomite. (The sulfur compounds would change and out-
>gas at lower temperatures).
> Your only recourse is to find Rutile from a different plant
>and hope it has less Fluorine compounds as contaminants.
> Good tests. Til later. Regards. Tom.
>
>Tom Buck ) tel: 905-389-2339
>& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
>(westend Lake Ontario, province of Ontario, Canada).
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Tony Hansen on sun 4 oct 98
> What percent of rutile are you using Tony in the glazes
> that you are having
> trouble with?
5-8%
--
T o n y H a n s e n thansen@digitalfire.com
Don't fight the dragon alone http://digitalfire.com
Calculation/Database Software for Ceramic Industry
June Perry on sun 13 oct 02
It seems that you aren't getting enough reduction. When I fired my rutile
blues, I started reduction early (usually around 1550-1650F and sometimes
even earlier)and maintained reduction throughout the firing.
Just a thought: are you using the same clay body?
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/index.html
June Perry on tue 29 oct 02
Dear Ivor,
I never reduced on cooling, nor did I fire down. I used a Geil fiber kiln
which cooled fast! I've done many chun tests over the years and what I found
was that a fairly thick application of the glaze with early reduction and
good periods of reduction throughout worked well. Some firings had alternate
periods of heavy reduction and neutral atmosphere and others had reduction
heavy and light throughout and I got good rutile blues either way.
I also think as I said, that having some early melters in there like zinc and
maybe the boron too, helped with these chuns.
It has been said by Tichane and other that chuns get their blue through the
optical effect of those little bubbles forming,etc. which I think would be
why you need a not too thin application of the glaze.
I noticed that the glaze the Clayarter posted that wasn't going blue didn't
have any boron or zinc and that may account for why even with good reduction
and the proper coloring oxides he wasn't getting the blue. That could be a
clue or just a coincidence.
One of these days when I get time I'd like to use the Ian Currie method to do
a bunch of rutile blue tests. I think one could garner a great deal of
information this way; but first I'd have to buld myself a little reduction
kiln again!
Warmest regards,
June
Kris Bliss on mon 17 feb 03
dear ingeborg
try a small batch with distilled water.=20
the other thing, if you were on city water at the old house, there may =
have been traces of soda ash from the treatment plant...that's what i =
found. my fix was to go to mom's house and get city h2o...in your case, =
maybe add a trace of soda ash to your water.
Also with your soak, let the temp drop 50 degrees and soak one hour.=20
next, make sure you have ceramic rutile not milled.=20
then, make sure you are using the same silica.
when you refire the pits and bubbles, put a drop of glaze in the =
holes...
hope this helps
kris in sunny anchorage, where there is no snow.
Lily Krakowski on tue 18 feb 03
Kris: If you need some snow, I can UPS a couple of tons.
I am with you on testing any badly performing glaze with distilled water.
But what is the difference between "ceramic [and] milled rutile" ?
Kris Bliss writes:
>... make sure you have ceramic rutile not milled.<
____________________________________________________________________________
__
>
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Kathi LeSueur on fri 11 may 07
Some time ago I posed the question, would calcining rutile help with the
pitting problems so many of us have who fire cone 10 reduction.
Yesterday I took the first tests out of the kiln. As I had hoped there
is no pitting on the surface. I weighed out the amount I needed for a
small batch of a problem glaze and then calcined the rutile to cone 05
during a bisque firing.
I'll now mix up a larger batch and test it on other forms. Perhaps we
might have the answer to those rutile blues.
Kathi
>
>
>
Tom at Hutchtel.net on sun 13 may 07
Kathy...We'll be waiting with whatever. I recently did some tests for Ron
Roy, and it seemed that his sub of EPK for the usual ball clay ( we use OM4)
also helped. (Also gave a better blue). It wasn't a direct sub, we
balanced the other oxides with Insight.
Tom
Subject: rutile blues
> Some time ago I posed the question, would calcining rutile help with the
> pitting problems so many of us have who fire cone 10 reduction.
> Yesterday I took the first tests out of the kiln. As I had hoped there
> is no pitting on the surface. I weighed out the amount I needed for a
> small batch of a problem glaze and then calcined the rutile to cone 05
> during a bisque firing.
Mimi Patrick on sat 26 may 07
Hi All - I too was having trouble with rutile blues on some Muddox clay from
Sacramento that I was using. The glaze suddenly became very pitted with
unhealed bubbles. Refiring the pieces did not help. I tried the same
glaze, same batch on some Laguna clay and it was fine. I strongly suspect
something in the clay out-gassing some kind of bad stuff. Maybe this will
help you.
Mimi Patrick
Argenta Earth & Fire Co.
www.nevpotter.com
Gene Arnold on mon 8 sep 08
Is there a special method required to get rutile to turn blue in =
reduction firings??? I see a lot of cone 10 reduction rutile blue =
recipes around, but every one I try comes out a very ugly milky green. =
Do they require heavy reduction?? Thick or thin application?? Just =
trying to figure out what I'm doing wrong.=20
Thanks!!!
Gene=20
mudduck@mudduckpottery.net
www.mudduckpottery.net
John Britt on mon 8 sep 08
Gene,
Try the O2 firing cycle in my book (page 109). Amazingly enough it work=
s!
And try the Rutile 11 it is a beautirul glaze. Oxidized firing with some
reduction at peak.
(Send replies to jbritt@main.nc.us For some reason I can't post from
that address.)
John Britt
www.johnbrittpottery.com/wks.htm
David Hendley on mon 8 sep 08
I have been firing rutile blues in my wood kiln for many years.
They can be tricky. I still can't get them to come out like I
want them all the time.
I agree completely with everything John Britt writes in his
book on pages 109-110.
It is imperative to run a line blend to find the optimum amount
of rutile needed for the best blue. Even less than a 1% difference
in the amount of rutile can make a difference. How much you
need depends on your circumstances, probably most
importantly, your firing.
For example John's Rutile Blue II has 8% rutile. In my glaze
base, in my kiln, 8% rutile would yield a white (ivory) glaze.
My rutile blue has only 3% rutile in it.
I treat rutile blue the same as copper red. In fact, I use the
same glaze base for both. See the "pottery" page of my
website for a photo of a red bowl and a blue bowl, side by side.
They are glazed with the exactly the same glaze, except the
blue bowl has 3% rutile in the mix.
www.farmpots.com/pottery.htm
The rutile blue mugs at the top of the page, by the way, have
a cobalt blue underglaze, with rutile blue over it, to produce
the extra deep blue. The blue bowl does not.
I think reduction is essential for the best, deep dark rutile
blues, the same conditions that produce copper reds. I base this
on the fact that when I have a good copper red firing I also have
great rutile blues. When my reds are not so good, the rutile
blues are not either. This would be a R1 firing in John's book.
Also, like copper reds, you want to apply a thick glaze coating.
David Hendley
Maydelle, Texas
david(at)farmpots(dot)com
http://www.farmpots.com
----- Original Message -----
Is there a special method required to get rutile to turn blue in reduction
firings??? I see a lot of cone 10 reduction rutile blue recipes around, but
every one I try comes out a very ugly milky green. Do they require heavy
reduction?? Thick or thin application?? Just trying to figure out what I'm
doing wrong.
Thanks!!!
Gene
mudduck@mudduckpottery.net
www.mudduckpottery.net
Bruce Girrell on tue 9 sep 08
Rutile blues are sensitive to application thickness. Test several different=
thicknesses.
Rutile has a high melting point, so don't try to cut your firing short; mak=
e sure you get a good solid cone 10. I have taken a liking to using draw ri=
ngs to determine when my rutile has actually melted and I don't shut down u=
ntil I see that the crystals have melted. If the rutile doesn't melt, the c=
olor is very muddy. I sometimes find the firing going to cone 12 to get a c=
omplete melt.
I have also learned two "secrets".
One is that iron seems to be required for a good rutile blue. Some people u=
se an iron wash under the glaze, some incroporate the iron into the glaze.
The second secret is that rutiles blues need to flow.
I accomplish these objectives by layering a low melting rutile glaze over a=
higher melting iron bearing glaze. Pete Pinnell's Cash Blue over top of Wo=
o Blue seems to work pretty well. Be sure that you have adequate kiln wash =
on your shelves!!!
Although most of what I know about rutile blues comes from my own experimen=
tation, I did manage to pick up a couple of hints from Bill Campbell. Bill =
Campbell has nailed rutile blue. The hint first came when I was looking at =
some of his pots in a gallery near where I live. Campbell had supplied some=
text for the gallery and it mentioned something about the difficulty of de=
aling with rutile glazes and that Campbell layers his glazes. The second hi=
nt came when I was at NCECA in Louisville. I was checking out the display o=
f Advancer kiln shelves and they noted that you should not apply kiln wash =
to the shelves unless you are using porcelain, in which case you should app=
ly kiln wash. They had some pictures of - guess who - Bill Campbell's kiln =
loaded with Advancer shelves. I looked closely at the photo and it was clea=
r that his glazes run like crazy.
So someone who is getting rutile glazes to work for him uses layering and u=
ses runny glazes. It's not much, but it does corroborate my findings.
Bruce Girrell
Edouard Bastarache on sat 4 oct 08
To Bill Merrill
Hello,
I have tested 1 recipe of rutile blue,
one with the standard light rutile :
http://rutileblue.blogspot.com/
and 1 with local 120 mesh synthetic rutile
derived from the refining of Quebec ilmenite :
http://ugsrutile.blogspot.com/
As you will see thickness of application is critical,
the same goes for the amount of rutile used; and
naturally they were fired in reduction.
As you will see, anything goes,
Gis la revido
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
Canada
http://www.flickr.com/photos/30058682@N00/
http://pagesperso-orange.fr/smart2000/livres.htm
http://www.flickr.com/photos/potier/20321056/
http://myblogsmesblogs.blogspot.com/
----- Original Message -----
From: "John Britt"
To:
Sent: Friday, October 03, 2008 9:44 PM
Subject: Re: iron blue glazes
Not to go against what anyone has said, but I have glaze guarantees and
actual recipes with common materials and mixing, application and firing
instructions in my book. You don't need a higher potassium feldspar than
Custer and for that matter, as I show with test tiles in my book, you can
get nice blue celadons with sodium feldspars!
It will definitely save you a lot of struggle and get you some beautiful
blue celadons.
I also have a glaze chemistry class and a celadon firing class if you need
it.
Let me know if you need some help at - jbritt@main.nc.us
(For some odd reason I cannot post at this address anymore, so I have to
log in at my wife's email. She really doesn't care about Clayart posts.)
Or you can go to my website for my email,
John Britt
www.johnbrittpottery.com/wks.htm
www.ncclayclub.blogspot.com
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