Chris Schafale on sat 21 nov 98
Attention Floating Blue lovers, the rest of you can hit delete --
First let me begin by eating some crow. Some time ago, I unguardedly
bragged that I had been using a floating blue variation that was
working very reliably in a community studio setting (except when it
didn't). So far, so good. However, now that I'm firing on my own,
I'm in the same boat as the rest of the world trying to use this
glaze (no, they wouldn't give me their recipe or firing schedule...).
I have several customers who looove this glaze, so I'm trying to
duplicate the results I used to get at the community studio in my new
kiln at home (same exact kind they use at the studio).
Anyway, I mixed up test batches of every variation I've seen on
Clayart, including those with and without Gerstley Borate, and they
all, without exception, came out that rather unattractive green. You
know the one. Tried a thinner application and a slightly lower final
temp, still green. Based on what I read, I probably need to
go even lower? Anyway, I'm willing to keep playing with
it, but all my recent glaze chem researches make me wonder
-- has anyone ever figured out *why* this blue glaze comes out green
if it's overfired even slightly?? Obviously cobalt stays blue to a
much higher temp than cone 6. Is it something about the rutile?
Would there be any way of increasing the maturing temp without losing
the color? Any ideas? TIA
Chris
Light One Candle Pottery
Fuquay-Varina, NC
candle@nuteknet.com
Sheilah Bliss on sun 22 nov 98
In a message dated 11/21/98 6:47:58 AM, you wrote:
<temp, still green. Based on what I read, I probably need to
go even lower? Anyway, I'm willing to keep playing with
it, but all my recent glaze chem researches make me wonder
-- has anyone ever figured out *why* this blue glaze comes out green
if it's overfired even slightly?? Obviously cobalt stays blue to a
much higher temp than cone 6. Is it something about the rutile?
Would there be any way of increasing the maturing temp without losing
the color? Any ideas? TIA
Chris
Light One Candle Pottery>>
Hi Chris -
I use a Floating Blue glaze and find that a thicker glaze application and a
higher temperature can help..... I've taken it to ^7 with 4-5 brushed on
layers (not dipped) and gotten good results. Could be the clay body I use -
Seattle Pottery Supply's Alpine White (^06-^6) - matters too... don't know
for sure.
Also, my firing cycle is long and slowish. Fire in electric kiln. Usually
do a "low" setting for 6+ hours, and then over the next 4 to 6 hours take it
up to high gradually. Let it cool down as slowly as possible, don't even
crack the lid or check peep-holes 'til the outside of the kiln feels cool.
Heard somewhere that the cool-down makes a big difference in how the colors
develop. Whenever I've tried to do a fast glaze firing, I've been more
disappointed than not, but then, I tend to want to use the neurotic glazes for
some masochistic reason.....
Only time I've gotten disapppointing results is when the glaze coat was too
thin
and when I've dipped rather than brush on the glaze. Could be a peculiarity
of the recipe I use - it's from Chappell's Clay and Glazes book. Here it is:
FLOATING BLUE ^6
Neph. Syen. 473
Gerst. Borate 270
Silica 203
EPK Kaolin 54
Red Iron Oxide 20
Co Oxide 10
Rutile (milled) 40
C.M.C. 10 teaspoons
Hope this helps!
Sheilah Bliss
Bliss Pottery
BlissPots@aol.com
Ron Wright on sun 22 nov 98
Have never ever had this FBG go green. Goes clear when very thin. Looks
terrific on a dark clay body. Well it did go a little green once when I
was in a hurry and didn't mix my glaze, just gave the bucket a quick
shake and went at it. Went green in spots.I think you might want to
check your rutile. If that is too strong or if you put too much in it
might dilute the cobalt. Under magnification my FBG looks blue with a
gazillion white dots in it. Hope this helps.
Recipe at http://www.concentric.net/~wrright
Ron Wright
3 Dogs Pottery
Therese (Terry) Madonia on wed 9 dec 98
from Therese Madonia
----------
> ----------------------------Original message----------------------------
> Attention Floating Blue lovers, the rest of you can hit delete --
>
> First let me begin by eating some crow. Some time ago, I unguardedly
> bragged that I had been using a floating blue variation that was
> working very reliably in a community studio setting (except when it
> didn't). So far, so good. However, now that I'm firing on my own,
> I'm in the same boat as the rest of the world trying to use this
> glaze (no, they wouldn't give me their recipe or firing schedule...).
> I have several customers who looove this glaze, so I'm trying to
> duplicate the results I used to get at the community studio in my new
> kiln at home (same exact kind they use at the studio).
>
> Anyway, I mixed up test batches of every variation I've seen on
> Clayart, including those with and without Gerstley Borate, and they
> all, without exception, came out that rather unattractive green. You
> know the one. Tried a thinner application and a slightly lower final
> temp, still green. Based on what I read, I probably need to
> go even lower? Anyway, I'm willing to keep playing with
> it, but all my recent glaze chem researches make me wonder
> -- has anyone ever figured out *why* this blue glaze comes out green
> if it's overfired even slightly?? Obviously cobalt stays blue to a
> much higher temp than cone 6. Is it something about the rutile?
> Would there be any way of increasing the maturing temp without losing
> the color? Any ideas? TIA
>
> Chris
> Light One Candle Pottery
> Fuquay-Varina, NC
> candle@nuteknet.com
>
From therese Madonia
I have a floating blue recipe that I have used for years. I have played
around with types of rutile and found that variations change the green.
Using light rutile will give a very green color. Using granular (which is
mixed shafes of rutile) or dark rutile will give a definite blue.I Also
use this glaze on a red or dark brown clay. On white clay, you also get
more green. If you want my recipe just e-mail me.
Therese Madonia
begonia@hatrack,net
gracie on thu 10 dec 98
Re: Floating blue going green... okay. here's what I've found.. I always
use whatever color rutile that's handy.. I get beautiful blues no matter
what.. on red clay it's very blue... I use Standard 112.. Still blue.. if
there is anything in the kiln with copper carb..THEN, I get GREEN!! So,
hope this helps... gracie ps..also the kiln will also have "leftover" fumes
from a previous copper based load and it will sometimes creep in my next
load of Floating Blue...
----------
> From: Therese (Terry) Madonia
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Floating Blue -- why the green?
> Date: Wednesday, December 09, 1998 11:39 AM
>
> ----------------------------Original message----------------------------
> from Therese Madonia
>
> ----------
> > ----------------------------Original
message----------------------------
> > Attention Floating Blue lovers, the rest of you can hit delete --
> >
> > First let me begin by eating some crow. Some time ago, I unguardedly
> > bragged that I had been using a floating blue variation that was
> > working very reliably in a community studio setting (except when it
> > didn't). So far, so good. However, now that I'm firing on my own,
> > I'm in the same boat as the rest of the world trying to use this
> > glaze (no, they wouldn't give me their recipe or firing schedule...).
> > I have several customers who looove this glaze, so I'm trying to
> > duplicate the results I used to get at the community studio in my new
> > kiln at home (same exact kind they use at the studio).
> >
> > Anyway, I mixed up test batches of every variation I've seen on
> > Clayart, including those with and without Gerstley Borate, and they
> > all, without exception, came out that rather unattractive green. You
> > know the one. Tried a thinner application and a slightly lower final
> > temp, still green. Based on what I read, I probably need to
> > go even lower? Anyway, I'm willing to keep playing with
> > it, but all my recent glaze chem researches make me wonder
> > -- has anyone ever figured out *why* this blue glaze comes out green
> > if it's overfired even slightly?? Obviously cobalt stays blue to a
> > much higher temp than cone 6. Is it something about the rutile?
> > Would there be any way of increasing the maturing temp without losing
> > the color? Any ideas? TIA
> >
> > Chris
> > Light One Candle Pottery
> > Fuquay-Varina, NC
> > candle@nuteknet.com
> >
> From therese Madonia
> I have a floating blue recipe that I have used for years. I have played
> around with types of rutile and found that variations change the green.
> Using light rutile will give a very green color. Using granular (which is
> mixed shafes of rutile) or dark rutile will give a definite blue.I Also
> use this glaze on a red or dark brown clay. On white clay, you also get
> more green. If you want my recipe just e-mail me.
> Therese Madonia
> begonia@hatrack,net
Lori Pierce on thu 10 dec 98
-----Original Message-----
From: Therese (Terry) Madonia
To: CLAYART@LSV.UKY.EDU
Date: Wednesday, December 09, 1998 12:26 PM
Subject: Re: Floating Blue -- why the green?
>----------------------------Original message----------------------------
>from Therese Madonia
>
>----------
>> ----------------------------Original message----------------------------
>> Attention Floating Blue lovers, the rest of you can hit delete --
>>
>> First let me begin by eating some crow. Some time ago, I unguardedly
>> bragged that I had been using a floating blue variation that was
>> working very reliably in a community studio setting (except when it
>> didn't). So far, so good. However, now that I'm firing on my own,
>> I'm in the same boat as the rest of the world trying to use this
>> glaze (no, they wouldn't give me their recipe or firing schedule...).
>> I have several customers who looove this glaze, so I'm trying to
>> duplicate the results I used to get at the community studio in my new
>> kiln at home (same exact kind they use at the studio).
>>
>> Anyway, I mixed up test batches of every variation I've seen on
>> Clayart, including those with and without Gerstley Borate, and they
>> all, without exception, came out that rather unattractive green. You
>> know the one. Tried a thinner application and a slightly lower final
>> temp, still green. Based on what I read, I probably need to
>> go even lower? Anyway, I'm willing to keep playing with
>> it, but all my recent glaze chem researches make me wonder
>> -- has anyone ever figured out *why* this blue glaze comes out green
>> if it's overfired even slightly?? Obviously cobalt stays blue to a
>> much higher temp than cone 6. Is it something about the rutile?
>> Would there be any way of increasing the maturing temp without losing
>> the color? Any ideas? TIA
>>
>> Chris
>> Light One Candle Pottery
>> Fuquay-Varina, NC
>> candle@nuteknet.com
>>
>>From therese Madonia
>I have a floating blue recipe that I have used for years. I have played
>around with types of rutile and found that variations change the green.
>Using light rutile will give a very green color. Using granular (which is
>mixed shafes of rutile) or dark rutile will give a definite blue.I Also
>use this glaze on a red or dark brown clay. On white clay, you also get
>more green. If you want my recipe just e-mail me.
>Therese Madonia
>begonia@hatrack,net
Knox Steinbrecher on thu 10 dec 98
No pure answers here but another puzzle. I have 2 kilns...both
electric....one with a computer controler and one without. The computer
controled gives me green and the manual gives me blue. Same bucket of
glaze......go figure. I happen to like the green I get. Also the blues.
Makes me feel like I'm firing reduction !!! I have a vivid imagination at
times.
knox in Marietta Ga...where it's getting colder and feeling more like winter.
David Gordon on thu 10 dec 98
Chris,
I've been using the standard Chappell recipe for floating blue for about
three years. Haven't had a problem with it going green since I adjusted
the firing to cone 5 with a 30 minute soak--total firing time approx. 11
hours. If I let it go to cone 6, it turns green.
Good luck,
David
Tom Buck on fri 11 dec 98
Gracie:
The chemistry is a bit weird but basically something akin to the
following is what happens to rutile (TiO2.FeO) in a highfire reduction
firing: the FeO stays as such and the Titanium oxide enhances the blue hue
(white light is reflected back by the FeO molecules as blue light). But
this FeO is touchy; some of it will switch around its crystalline
structure (Does some Fe2O3 form?) fairly easily if nudged. And that is
what copper metal vapour does.
When a pot coated with a copper red glaze (the copper compound in
the glaze mix is usually copper carbonate basic these days), when this pot
is fired to C10+ under reducing conditions, the copper compound goes first
to black copper oxide, then to red copper oxide and finally some of the
red copper oxide is changed to copper metal. At C10 much of the copper
metal goes to vapour (which is why most Cu red glazes use twice the amount
of copper compound than that that actually ends up on the pot as copper
red). And some of this copper metal vapour will touch nearby pots, the
kiln walls, etc., and make a "blush" glaze in some cases. Also, some of
the copper will deposit on rutile-glazed pots and upset the Ti/Fe blue hue
(which some believe comes from a mix of yellow and green), and as a result
the rutile-coated pot will come out of the kiln coloured green rather
than blue.
Tom Buck ) tel: 905-389-2339 & snailmail: 373 East
43rd St. Hamilton ON L8T 3E1 Canada (westend Lake Ontario, province of
Ontario, Canada).
Knox Steinbrecher on sat 12 dec 98
Tom
OK--I follow, but your description was for reduction environment. Floating
blue is an oxidation glaze.....does the same chemistry hold true?
Knox in Marietta Ga
MRS SANDRA L BURKE on sat 12 dec 98
Chris--I can't explain why it goes green, but I can tell you that
when we use it at the school I teach at, a thinner application
results in either a non-descript browm or an ugly green, med
thickness darker blue, thick application pale speckled blue. I have
also noticed that when a pot glazed with a glaze containing alot of
red iron oxide it will flash green on that side. I too have tried all
sorts of things to get the glaze to be consistant (at least most of
the time), Usiing distilled water for instance, etc. Sometimes the
glaze just doesn't want to cooperate----regardless-----which
frustrates my students, they all want a pretty blue-----ah well
wlithout suprises life would be pretty dull.
Sandy B.
please excuse any typos---I slashed my finger on a student pot
yesterday-----Some of them insit on leaving sharp edges no matter
what I say!
| |
|
