Joyce Lee on fri 12 apr 02
Unloaded a bisque firing in which I'd
placed a 4 hear old "shino" pot (ugly, squat, yucky) on which the =
"shino" had fired a bilious light green over oatmeal.
A couple of years ago I refired it in the
original ^10 reduction ...... results: no discernible change. In this =
bisque firing at ^06,
however, the glaze is orange ..... inside and out ..... not rust, and =
not as orange as the fruit .... but definitely a shino orange. =20
The pot continues to be heavy, squat etc .... the only interest I have =
in it is its glaze history. I've refired copper reds in bisque loads at =
^06
with happy results usually, but=20
never shino. Does anybody have any idea what happened? Is this a =
common
occurrence? I'm planning to do the same to every pot presently wearing a =
glaze which didn't meet expectations ..... most are shinos. I've had =
much GOOD luck with shino, too, I hasten to add .....
Joyce
In the Mojave still rolling slabs ..... I want
some Good Looking large wall plaques/plates to hang on the new lattice=20
fences ... not too many..... tacky ..... only a couple..... figure I'll =
probably have to fire
a dozen or so to get the ones I envision.... maybe not ..... maybe more =
....
claywork is SUCH an Exact Science.....
Dannon Rhudy on fri 12 apr 02
At 10:12 AM 04/12/2002 -0700, you wrote:
>Unloaded a bisque firing in which I'd
>placed a 4 hear old "shino" pot ..... In this bisque firing at ^06,
>however, the glaze is orange ..... .......
Joyce, the bisque fire gives time for the iron in the shino
to migrate to the surface and make that orange color. Sometimes
refiring in bisque can help shino that is unsatisfactory; doesn't always
work. That's why Hank Murrow holds his shino firings at around
2000F or so on the cool-down. Makes yummy stuff.
That is a VERY thin layer of color, by the way.
regards
Dannon Rhudy
inside and out ..... not rust, and not as orange as the fruit .... but
definitely a shino orange.
>
>The pot continues to be heavy, squat etc .... the only interest I have in
it is its glaze history. I've refired copper reds in bisque loads at ^06
>with happy results usually, but
>never shino. Does anybody have any idea what happened? Is this a common
>occurrence? I'm planning to do the same to every pot presently wearing a
glaze which didn't meet expectations ..... most are shinos. I've had much
GOOD luck with shino, too, I hasten to add .....
>
>Joyce
>In the Mojave still rolling slabs ..... I want
>some Good Looking large wall plaques/plates to hang on the new lattice
>fences ... not too many..... tacky ..... only a couple..... figure I'll
probably have to fire
>a dozen or so to get the ones I envision.... maybe not ..... maybe more
....
>claywork is SUCH an Exact Science.....
>
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Hank Murrow on fri 12 apr 02
Joyce wrote;
>Unloaded a bisque firing in which I'd
>placed a 4 hear old "shino" pot (ugly, squat, yucky) on which the
>"shino" had fired a bilious light green over oatmeal.
>A couple of years ago I refired it in the
>original ^10 reduction ...... results: no discernible change. In
>this bisque firing at ^06,
>however, the glaze is orange ..... inside and out ..... not rust,
>and not as orange as the fruit .... but definitely a shino orange.
>
>The pot continues to be heavy, squat etc .... the only interest I
>have in it is its glaze history. I've refired copper reds in bisque
>loads at ^06
>with happy results usually, but
>never shino. Does anybody have any idea what happened? Is this a common
>occurrence? I'm planning to do the same to every pot presently
>wearing a glaze which didn't meet expectations ..... most are
>shinos. I've had much GOOD luck with shino, too, I hasten to add
>.....
Dear Joyce;
Firing a shino pot again to C/010 or more is pretty much
equivalent to doing an oxidizing soak during the
cooling.........giving the iron crystals a chance to grow at exactly
the temp they like to grow at. The trick is; you have to have the
reduction in the first place for the soak to work. The small amount
of iron in the shino must be reduced to make it active in the melt
and available for later re-oxidation in the cooling.....or re-firing
as in your case.
BTW, sometime take one of those clunkers that has the nice
shino firecolor and break it. My bet is that the glaze is white just
under all that red!
Cheers, Hank
Jocelyn McAuley on fri 12 apr 02
What fun refiring Joyce!
I had a quick question: you mentioned refiring copper-reds this way
successfully... are you reducing when you bisque fire? Does a successfull
refire of your reds, mean you get a red pot?
--
Jocelyn McAuley ><<'> jocie@worlddomination.net
Eugene, Oregon http://www.ceramicism.com
Hank Murrow on fri 12 apr 02
>At 10:12 AM 04/12/2002 -0700, you wrote:
>>Unloaded a bisque firing in which I'd
>>placed a 4 hear old "shino" pot ..... In this bisque firing at ^06,
>>however, the glaze is orange ..... .......
>
>Joyce, the bisque fire gives time for the iron in the shino
>to migrate to the surface and make that orange color. Sometimes
>refiring in bisque can help shino that is unsatisfactory; doesn't always
>work. That's why Hank Murrow holds his shino firings at around
>2000F or so on the cool-down. Makes yummy stuff.
>That is a VERY thin layer of color, by the way.
>
>regards
>
>Dannon Rhudy
>
Dear Dannon;
Pamela Vandiver and I did many scans with the SEM (scanning
electron microscope) and the microprobe on my shino samples four
years ago. We could find no evidence of a concentration of iron at
the surface. The concentration remained remarkably equal throughout
the entire glaze thickness. It IS very difficult to not believe that
iron is concentrated, especially when you can see white just under
that red color if you break one open. We believe that the iron that
IS at the surface is available for re-oxidation during cooling or
subsequent refiring. It seems that a miniscule amount (less than 1%)
is all it takes to produce the red color.....if the firing conditions
and glaze chemistry permit. Most of that iron is from impurities
mostly in the lithium-bearing compounds (lepidolite, spodumene,
petalite, etc.) and the kaolins. I was SO convinced that the iron was
'moving' to the surface........but testing blew that theory away.
It IS true that irony bodies will give stronger color, but
once the iron is in the glaze, it appears to be uniformly distributed.
Cheers, as always, Hank in Eugene
Liz Willoughby on sat 13 apr 02
Hi Joyce, I too have refired shino pots in the bisque at 04. They
did come out more orange, but noticed that there was some pitting
going on. Then Hank was talking a while back about his refiring
shinos or holding the temp going down during a glaze firing at 1950
-2000 F. for a couple of hours, (I think). Anyway, I had some very
black and some very boring looking peachy shinos that I refired
together in my electric kiln. I took it up to 1950 and held it there
for 2 hours, and I was very happy with the results. The peachy
shinos because deeper in color, had more life in them, but the black
sooty looking shinos lustred and became gold in color. Really a
pleasant surprise, and very successful. Not all the black burned
away, just some, with this wonderful gold color in between.
I figured I had nothing to lose, and really did not expect such good
results.
I think if you have enough pots to load your electric kiln you should
take it up higher than bisque, 1950 at least, hold for 1 1/2 - 2
hours and you will like the results even more.
Good luck, Liz
Joyce says:
>Unloaded a bisque firing in which I'd
>placed a 4 hear old "shino" pot (ugly, squat, yucky) on which the
>"shino" had fired a bilious light green over oatmeal.
>A couple of years ago I refired it in the
>original ^10 reduction ...... results: no discernible change. In
>this bisque firing at ^06,
>however, the glaze is orange ..... inside and out ..... not rust,
>and not as orange as the fruit .... but definitely a shino orange.
Liz Willoughby
RR 1
2903 Shelter Valley Rd.
Grafton, On.
Canada
K0K 2G0
e-mail lizwill@phc.igs.net
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