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a bone ash glaze

updated wed 19 aug 09


Ellen Currans on mon 17 aug 09

In l991 in an article in The Potter's Network ( 4 times a year from The=3D2=
Potter) I found a wonderful Bone Ash glaze submitted by Jeff Cox who was
then at the 92nd Street YM-YWHA. I used it in many color variations for
about 10 years - until I ran out of a good source of the right kind of=3D20
Bone Ash.
When I was running out, I ordered Bone Ash from 5 or 6 suppliers, and=3D20
from England. Only a few random leftovers from fellow potters actually=3D
worked the same
way, and after a lot of testing, I gave up on that particular glaze. =3D20
I used it
on tile for the bathroom and kitchen in a house we are building, and=3D20
also for tiles for
the window ledges, as well as lots of pots.

You can't count on "bone ash" listed in the supply catalogs as being=3D20
the right kind
to work in this glaze. Some substituted TCP and acted as if they=3D20
didn't even know
about the real stuff. The English bone ash was very coarse and=3D20
obviously didn't work as
well as the finer. What I liked about the glaze was the opalescence=3D20
and fatty surface,
and also the variation from warm white to a bit rusty on the edges. =3D20
Either because of
the clay I was using or the bone ash itself, I also got some small warm=3D2=
iron spots which
were pleasing on the plainer work I made then. The wrong bone ash did=3D20
not have the
fine iron spots and in many cases the glaze did not melt at all.=3D3D0

I found that this glaze takes oxides and stains beautifully and I had 8=3D2=
or 9 buckets of the
stuff in pleasing colors that worked very well overlapped or slip=3D20
trailed on top of each other.

I never had this glaze tested for stability but it has been on my=3D20
counters and a bathroom
sink for 9 years with no scratching or wearing or staining.. I did=3D20
quit using a dark green version
with 5% Masons green stain 6280 because of the lemon test discoloring=3D20
it. I was able to
get soft melon pinks and yellows with this glaze and stains. It would=3D2=
be nice to get
an official opinion on its stability, because it certainly sounds like=3D20
a crazy glaze.


REAL BONE ASH ------ 35
UNISPAR 50 -----------35 (originally Kona F4)
EPK ------------------------15
ZIRCOPAX----------------- 2 (I added this to the original recipe)
BENTONITE--------------- 2 `'' '' '' =3D2=

Application is everything. Too thin and it is more brown. Too thick=3D20
and it is
a rather dull white. Loves an average thickness with good body and=3D20
glaze reduction.
A warm white with the surface breaking into earth tones. It has=3D20
qualities of orange peel
in a salt firing and is nice as a liner. It has a lovely, opalescent=3D20
depth to the glaze.

Thanks to Hank and Peter Pache for the inf
ormation on where to get the=3D20
real stuff.
I may have to try this one again. This sounds quite similar to Hank's=3D2=
=3DC3=3D87orey's Wierd - using
Soda Spar instead of Neph Sye.

Ellen Currans
Dundee, Oregon