Bill Merrill on sun 29 jul 07
The feldspar pieces are 1/8"th to slightly larger. They are not round,
but somewhat flat. I don't want them all the same and they all vary in
size. I wedge the pieces into tea bowls or force it into the clay
surface. Sometimes an Avery slip is brushed over the entire surface of
the form. The spar pops through the slip. The more clear spar looks
clear to start and you can see the layering effect in the piece of spar
before I soak it and fast fire it to about 1200 degrees. The pieces
just separate and are the peeled apart. Most feldspars do not have this
quality. If the spar is glazed over you will still see the spar. It is
especially effective in a soda or wood fired kiln. They have a
Shigaraki look to them. When the spar is clear and put over a glaze, the
glaze shows through and the area looks like an ice field that you can
see though. I fire to cone 10, with the cone bending to 1 o'clock, then
shut off the kiln and the cone bends to 3 o'clock. I usually cool the
kiln for 3 or more days. I start reduction at cone 010 and reduce the
kiln until it is ready to shut off. I fire from 010 to cone 10 in no
less than 8-10 hours. Many of my glazes are matt and the long slow
reduction and cooling benefit my glazes.
I just put slides on a disc and tried to put in the email...it didn't
work for me. I will send you pictures later this week.
Most feldspars are not like the one I use and dig in Wyoming. The are
more opague and don't layer like the Wyoming feldspar. =20
I have a friend in Waynesville. He is a glass blower but is starting to
make pots again. He's a great potter and glassblower. Have you seen
John Nickerson's glass? His web site is www.nickersonglassworks.com
Do you know Bob Brotherton? He also is a potter from the Ashville area.
Bill
-----Original Message-----
From: Curtis Nelson [mailto:curtn@earthlink.net]=20
Sent: Sunday, July 29, 2007 9:24 AM
To: Bill Merrill
Subject: Feldspar Post on Clayart
Bill -
What size feldspar granules are you aiming for when you hammer mill=20
your home-dug feldspar? Random size results, I suppose, but how large=20
would you say are the biggest pieces? Big enough to be able to observe=20
the melting at least, I guess. Two millimeter diameter chunks perhaps?
Since the feldspar melts from being an opaque white to a clear, What=20
does the claybody surface look like after firing? Are the now-clear=20
feldspar granules that are at the surface now visible in their little=20
craters? Would glazing obliterate the coarse surface, or are the=20
resultant depressions deep enough to retain the integrity of the rough=20
pre-fired surface?
In short, what's the bisqued surface look like? What's the glaze-fired=20
surface look like?
What temperature do you have to fire to to get the feldspar to melt?
Separately, when you fast-fire larger chunks of spar previously soaked=20
in water, you obviously have no problem with steam explosions. Is there=20
an explanation for this behavior, or is it a matter of :well, that's=20
the way it is?
What cone are you going to, to get these thin sheets it separates into?
And when you layer the sheets over raw glazes, what result are you=20
getting?
Any answers you can help me with will be much appreciated. Having some=20
knowledge before I start any testing of my own, goes a long way.
Best -
Curtis Nelson
Asheville, NC
Lee Love on sun 29 jul 07
On 7/29/07, Bill Merrill wrote:
> especially effective in a soda or wood fired kiln. They have a
> Shigaraki look to them.
Most examples I have seen trying to duplicate co-shigaraki in
America don't look like shigaraki, because the feldspar is not like
shigarki, which is weathered. I am guessing putting chips in a ball
mill might help.
I bought a 30kg bag of the shigaraki feldspar granuales just
before I left and brought a sample with me. They compare nicely to
the neph sye granuale sample Craig Edwards gave me. I was stunned
when I saw them. Only difference is that there was more a variety of
sizes. The co-shigaraki feldspar is screened out of the clay, sized,
and put back.
I fire co-shigaraki homome from cone 11 to cone 14. I
then buff the surface after firing, so it feels nice to touch.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
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