will edwards on tue 26 dec 00
Hello,
In regards to Cobalt greens I thought I would lend this information. In m=
ixing
many new glazes I found that adding rutile is where I am seeing the green=
turn
up.
Rutile is TiO2 and a small trace amount of iron according to my analysis.=
Also
I had no zinc in any of the glazes where I got this green.
In one of the mixes I have a great 3-D effect where I have a green backgr=
ound
with a slight blue floating just under a clear. Nice effect!
Also this may answer so many of the questions about the floating blue tur=
ning
to floating green when it is fired to a full ^6 ox.
It does appear to have some realtionship with the rutile. I also have bot=
h
light rutile and tan rutile.
On a white clay it is more pronounced than on an iron bearing clay like
Lizella. So I am pondering that it is the TiO2 that causes the reaction w=
hen
fired to a specific temperature. I don't fire under ^6 so I have nothing =
there
to base the temperature issue on.
I did notice in one of the calculations that Cr203 and V205 is present in=
trace amounts as well as a bit of ZrO. I order in bulk so I will need to =
look
at the latest information when work resumes.
I have read where many people become disillusioned with Floating blue bec=
ause
it turns green many times at ^6. With this information it tells me they m=
ust
be a point where they are certainly some chemical changes that take place=
around that temperature range that is so near the line that the reaction
occurs. It would be most interesting to see a very controlled effort at ^=
5 and
5/1/2 to 7+ in order to fully understand if this is the case?
Of course observations on these recipes have also shown to be different b=
ut
the colorant oxides generally have remained the same. Rutile and cobalt. =
So
the alchemy is once more on. I have to laugh at myself when I think of hi=
tting
the send button because I bet this has been covered. I just didn't find i=
t in
the archives this early in the a.m. where my eyes are hardly working.
William Edwards
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will edwards on thu 28 dec 00
Hello,
I noticed that Albany slip is also high in magnesia and does contain a mi=
nute
amount of TiO2. Ian Currie recently made a good point to me but it would =
take
more analysis for me to fully understand regarding the close association
between certain materials that give green cobalt.
I do think the grid method would ease the strain of hunting out specifics=
but
when you find them and run them on calculations be certain that they are
within limits.
This is all one big balancing act to have good glazes that both look grea=
t and
are food safe and compatable with other mechanicial things such as stove,=
microwaves and dishwashers.
All that would imply that a person is only going for utilitarian use only=
=2E I
understand not all glazes are for such use but until we have everyone pri=
nting
out glazes that are specific in content and context on safety I must cont=
inue
assuming I may eat from those vessels and I really get enough nutrients a=
nd
colloidal minerials as it is.
I use to fire ^10R. I have since moved down to ^6 Ox. I have decided to
dedicate the rest of this life time looking for methods to better underst=
and
Mid-fire range formulations. More people have worked the ^10's over the y=
ears
and found almost every aspect out they could. Cone 6 has delivered to me =
a
group of colors that resemble some of the best ^10 R firings I had. (No b=
right
reds)
Now that more People have access to such kilns and firing ranges you can
understand my need to look at the utilitarian aspect as well as those
delicious ^6 'ers that come out of the fire with zest and sex appeal.
Since I have linked myself with working heavily with mid-range stoneware =
that
does not exclude my research on shifting those 10's down to a lower temp.=
Some
work, some don't!
Alchemy - Fighting the glaze dragon, praying to the kiln Gods and mixing
glazes in a caudren. =
William Edwards
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will edwards on sun 31 dec 00
Hello,
They are some fleeting issues when dealing with certain colors. Grid patt=
erns
show that the usual fix of cobalt green is within a certain range where h=
igh
alumina is at. (Based on sources) If that is correct, if not, someone wil=
l let
me know I hope!
I had worked a recipe to death when I first started looking for cone 6 gl=
azes
that would appeal to the eye and look more like a ^10 glaze so here is on=
e of
my old stand-by's that I called Mossy River Rock Black. It is almost a bl=
ack
but covered with mossy green flecks of color. (Friend of mine won a ribbo=
n at
a juried exhibition dang his time because of that glaze.)Jon Brinley I ho=
pe
your ears are burning.
Alumina is low here but magnesia is high and boron is above 5.00 and of c=
ourse
plenty of iron.
We used it on jugs and things that needed a very old look. It is among
hundreds of glazes I have written, re-written or toyed with since I came =
into
the game.
I also think that many times we over-look some of the other materials lik=
e
magnesia playing a role in some of the colors and trace elements influenc=
ing
them as well.
The only other thing I might add is this glaze has no TiO2 in it except a=
trace. But that mossy green rivulets of color are roaming all over the to=
p of
the near black back-drop. It looses this where tin is applied and will go=
to a
nice brown.
Now you see why I like the term alchemy. About the time we get something =
down
pat something else will change the pattern like magic!
Those who have a small amount of GB left I ask you try this glaze and rep=
ort
back to the group. I am fixing the version now with frits and so far so g=
ood.
(decorative use/no lab work was done) As stated it was limited on the out=
side
of face jugs and other things like flower pots, etc.
Recipe Follows:
William Edwards
Alchemy - Give me that old time alchemy, its good enough for me.
(Mossy River-Rock Black) ^6 Ox.
Flint ( Quartz Silica ) 30.46
Gerstley Borate 25.18
Soda Feldspar 25.18
Talc 14.18
Epk Kaolin 5.00
Cobalt Carbonate 1.50
Red Iron Oxide (ferric) 10.00
Wear NIOSH approved respirators and gloves and now include bonnets or sho=
wer
caps unless you are bald. Bald people like me can use spray adhesive to
attract the dusts to one location and then rub it off with minerial oil.
Right!
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