Hannah on fri 31 may 02
With all the talk about cobalt green glazes, I decided I should =
contribute a recipe for a cone 9/10 reduction glaze. This will deliver =
the most beautiful, rich, smooth matt, deep green ever. (I don't =
remember where I got it) I achieved the green by brushing a mixture of =
cobalt and water over the glaze. You can also add .5 CoO to the base =
glaze. Sometimes I added both cobalt and .7 CuCo for a blue/green. =
Notice the decimal points before those numbers. I haven't used it in =
maybe 25 years (!) because it can be fickle. Too thin and it will be =
brown, too thick and it will run...alot. It's called Spotted Matt =
because it often forms crystals of a lighter color. Very nice, but =
sometimes it went frosty, which I didn't like. It conforms to what =
the gurus have been saying - that it's necessary to have titanium for =
cobalt to go green. =20
SPOTTED MATT, CONE 9/10 REDUCTION
Potash Feldspar 45
Barium Carb. 18
Kentucky Ball Clay 9
Whiting 8
Rutile 7
Zinc 7
Bone Ash 5
Titanium Dioxide 1
A spotted creamy white base, which will turn a cobalt wash to deep =
green. =20
I would be very interested to hear what results anybody might get.
Warmest wishes to all,
Hannah Brehmer, Lake Tahoe, CA
PS The printer made a typo on the posters - is redoing them! I =
have the tubes and will mail them out as soon as I can.
=20
Ron Roy on tue 4 jun 02
Just a heads up on this glaze - it is unstable and will leach Barium into
food - how fast and how much only testing will tell.
I calculated it with G200 and OM#4 - most times zinc oxide will not be
there at the end of a reduction firing so I calculated it without the ZnO
as well - it's still unstable without the ZnO.
I would not be surprised to see the colour change when in contact with
food. Leaving orange juice overnight - in a cup lined with this glaze would
produce and interesting taste test - but I do not recommending swallowing
any.
RR
>With all the talk about cobalt green glazes, I decided I should
>contribute a recipe for a cone 9/10 reduction glaze. This will deliver
>the most beautiful, rich, smooth matt, deep green ever. (I don't
>remember where I got it) I achieved the green by brushing a mixture of
>cobalt and water over the glaze. You can also add .5 CoO to the base
>glaze. Sometimes I added both cobalt and .7 CuCo for a blue/green.
>Notice the decimal points before those numbers. I haven't used it in
>maybe 25 years (!) because it can be fickle. Too thin and it will be
>brown, too thick and it will run...alot. It's called Spotted Matt
>because it often forms crystals of a lighter color. Very nice, but
>sometimes it went frosty, which I didn't like. It conforms to what the
>gurus have been saying - that it's necessary to have titanium for cobalt
>to go green.
>
>SPOTTED MATT, CONE 9/10 REDUCTION
>
>Potash Feldspar 45
>Barium Carb. 18
>Kentucky Ball Clay 9
>Whiting 8
>Rutile 7
>Zinc 7
>Bone Ash 5
>Titanium Dioxide 1
>
>A spotted creamy white base, which will turn a cobalt wash to deep green.
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