Lesley Alexander on thu 21 sep 00
Thanks to Craig Martel for the ^10 celadon recipes he's been
posting! One I've been using came out a greenish brown grey (for me),
good consistency, though I'd like it a bit less brown grey. That one
was G-200 feldspar 28.49%, EPK 17.83%, Whiting 15%, Silica 28.58%,
Dolomite 4.43%, Albany slip 4.72%, and red iron oxide .94%.
Recently he has posted a blue celadon. (Blue Celadon: Kingman
spar 55.17, whiting 14.15, silica 30.68, black iron oxide 1%.). I mixed
it with Custer spar, ball milled it with the black iron oxide, and did a
a series adding 2% strontium up to 8%. They all looked the same to me.
It had to be thick to get the blue, but my 8% crazed where pooled in a
dish, so I guess 8% is too much. Maybe he'll have a chance to try it
with other iron oxides, and with barium.... maybe barium goes bluer?
Then there's Deller celadon reviewed by Pete Pinell. My try at that
one crazed pretty severely. My mix crazed and I wanted a food-worthy
product. So, trying to calculate dry percentages (a bit rough!) I tried
a series adding silica, and another adding grolleg, and a third with
both. The silica sample came out a lovely blue, the grolleg slightly
greener and (muddier?) but fatter looking. Can't see that any of them
crazed, but maybe they will accomodate later! .
Just some ruminations from an amateur plodding along. Suggestions
and comments welcome. I'm looking for an interesting glaze to use with
food; do have some fine white liner glazes already. I love the
toasty-brown sticky caramel candy look of Shino when it goes that way,
but such a small percentage delivers a good brown in my updraft
kiln...... so far the successes have held up for me in use. Cheers!
Keiko Suga & Noel Oard Mapstead on thu 21 sep 00
hi lesley
i am currently working with chinese blue jun celadon, using different percetages of
bone ash. i teach a workshop in feb 2001, using human bone ash for a glaze
ingredient
current recipes i am using come from nigel woods recent book 1999,
chinese glazes, here is one for example:
31 buckingham; 12.5 epk; 34 flint; 12 whiting; 4.5 dolomite; 2 red iron oxide; 4
bone ash; .1 magnesium dioxide; .35 titanium dioxide;
apply thick; reduction cone 10; cool slow/apply copper wash over dry glaze for
copper reds
noel oard mapstead
Verna Lucas on fri 22 sep 00
What cone are these please. ^5/6 or ^10, oxidation of reduction.
Thanks
Craig Martell on fri 22 sep 00
Lesley sez:
>Thanks to Craig Martel for the ^10 celadon recipes he's been
>posting!
Hi:
Yer welcome!
>Recently he has posted a blue celadon. (Blue Celadon: Kingman
>spar 55.17, whiting 14.15, silica 30.68, black iron oxide 1%.). I mixed
>it with Custer spar, ball milled it with the black iron oxide, and did a
>a series adding 2% strontium up to 8%. They all looked the same to me.
>It had to be thick to get the blue, but my 8% crazed where pooled in a
>dish, so I guess 8% is too much. Maybe he'll have a chance to try it
>with other iron oxides, and with barium.... maybe barium goes bluer?
Being the total glaze nerd that I am, I did a seger of your substitute with
Custer. As I thought, the potassium was a bit low for a blue celedon, or
what I've seen lately as good blues with high potash/lime fluxes. I redid
the custer blend for you and I'll post it below. If you can get the
potassium at about .3 moles you will get a nice blue celadon. Custer has
about 2% less K in the analysis than Kingman so it throws you off a
bit. The adjustment is close to my original but the Si/Al ratio is a bit
lower. I was looking at about 12/1 as my target. I will also include the
adjusted glaze with the amount of BaCo3 I add to get a nicer blue. I don't
know if barium bothers you in terms of your own health or that of customers
but this is a small addition for a nice effect and I plan to have these
glazes tested for release. I'm betting heavily on "no problem" because
they are high in silica and the alumina is sufficient. See below.
Blue celadon cone 10R
=====================
Custer feldspar..... 63.90 63.90%
whiting............. 13.29 13.29%
silica.............. 22.81 22.81%
========
100.00
CaO 0.58* 8.12%
K2O 0.30* 6.98%
Na2O 0.13* 1.97%
Al2O3 0.46 11.78%
SiO2 4.72 71.07%
Fe2O3 0.00 0.08%
Cost/kg 0.41
Si:Al 10.24
SiB:Al 10.24
Expan 7.52
Blue celadon2 cone 10R
======================
Custer feldspar..... 62.34 62.34%
whiting............. 11.06 11.06%
silica.............. 22.32 22.32%
barium carbonate.... 4.28 4.28%
========
100.00
BaO 0.09* 3.53%
CaO 0.49* 6.79%
K2O 0.29* 6.81%
Na2O 0.13* 1.93%
Al2O3 0.46 11.49%
SiO2 4.67 69.38%
Fe2O3 0.00 0.08%
Cost/kg 0.45
Si:Al 10.25
SiB:Al 10.25
Expan 7.62
These glazes need to be tested before use. Glaze #1 without Barium is food
safe. The glaze with barium should be tested for Ba release and at this
point I can't give it the OK for food use.
Add 1% black iron oxide for a blue celedon to each glaze.
later, Craig Martell in Oregon
| |
|
