John L Worner on fri 11 apr 97
Hi!
Does anyone have a reliable recipe for a Chun Blue or other Blue that does well
in
reduction over an iron rich claybody. We currently have a nice Chun that does
well
over white stoneware and porcelain, but on iron rich clays it all but
disappears.
This is what we are currently using:
CHUN BLUE ^ 9-10 RX or OX
Whiting 284 (I guess you could use Wollastonite instead as
described in
Tony Hansen's Magic of Fire)
Custer F. 284.5
Kaoling 221.7
Flint 203.7
Magn. Carb 35.7
Add:
Ultrox 10% 104
Rutile 5% 52
Cobalt OX 1% 10.4 (You can use the carbonate for a greyer tone of blue)
Red Iron Ox 1% 10.4
Anne Worner
Jon Pettyjohn on sat 12 apr 97
Hi Anne,
I have a Chun blue that works well over dark slips and glazes
(tenmoku), I'm not sure though if our materials here in the
Philippines will match yours, but it might be worth a try.
^9-10 R Chun
Raval Feldspar 40.00%
(almost identical to Cornwall Stone)
Whiting 18.00
Kaolin 10.00
Silica 25.00
Titanium Diox. 7.00
+
Iron Ox. 1.00
If too thin the glaze is mauve transparent, if too thick opaque off-white.
The trick is to get the thickness just right to produce the
opalescent blue.
Tenmoku (base glaze for above)
Raval Feldspar 65.00%
Whiting 18.00
rice straw ash 7.00
(Any high silica ash would be a good substitute, grass ash should
work well, rice straw is about 98% silica with high phosphor content)
Silica 10.00
+
Iron Ox. 6.50
I'm anxious to test the recipe you gave too since mine is not so good
on white clays.
Bye,
Jon Pettyjohn Manila jon@mozcom.com
> Does anyone have a reliable recipe for a Chun Blue or other Blue that does wel
> in
> reduction over an iron rich claybody. We currently have a nice Chun that does
> well
> over white stoneware and porcelain, but on iron rich clays it all but
> disappears.
Tony Hansen on sat 12 apr 97
> We currently have a nice Chun that does well
> over white stoneware and porcelain, but on iron rich clays it ...
How about a white slip under the glaze. Iron in clays bleeds into
glazes and changes the appearance rather drastically on many.
--
Tony Hansen, IMC thansen@mlc.awinc.com
Pierre Brayford on sat 12 apr 97
John L Worner wrote:
>
> ----------------------------Original message----------------------------
> Hi!
>
> Does anyone have a reliable recipe for a Chun Blue or other Blue that does wel
> in
> reduction over an iron rich claybody. .......
> Anne Worner
Yes! Ihave been using this glaze for some years - it originated with
Derek Emms and was published in Ceramic Review.
Potash Feldspar 43
Flint (or Quartz) 30
Whiting 20
Talc 5
Kaolin 2
Red iron oxide 1
Colemanite (Gerstley
Borate) 1
__________________________
Needs reduction ^9 - 10 The firing temp affects it considerably.
Works well over Tenmoku type glazes or dark bodies. The colour is an
optical effect and the dark body helps the colour.
June Perry on sat 12 apr 97
Dear Anne:
Just quickly looking at your recipe it should be fine on an iron rich body in
reduction. Normally, you get more color with chun on an iron body because the
iron contributes to the optical blue color of chun glazes. You may not be
reducing enough or early enough. Chuns needs good reduction for good color
development. I have a chun glaze that can look dull ochreish when not
reduced, lavendar when reduced medium and a deep rich purplish blue in heavy
reduction.
Regards,
June
June Perry on sat 12 apr 97
Oh, by the way, without going too much into the technical aspects of it,
wollastonite is not a direct substitution for whiting! Wollastonite contains
calcium and silica and is known to help give brighter colors in glazes, but
it is not a direct substitution for whiting which only contains calcium and
no silica.
Regards,
June
Jan Cannon on sun 13 apr 97
You might try the following Chun (Jun) glaze. I use it over a dark
stoneware body with a white slip and reduction fire to cone 10. I have a
Yuan dynasty Jun shard and this glaze matches it very closely. On my home
page there is an example of the glaze though it looks better in real life.
Chun Type, 1300 C, Reduction (Bell-Hughes)
CUSTER FELDSPAR 48
FLINT 32
WHITING 16
BONE ASH 4
IRON OXIDE RED 1
--------------------------------------------------------
Jan Cannon Tel: 802-425-6320
19 Garen Road jcannon@together.net
Charlotte, VT 05445 http://www.together.net/~jcannon/
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