John Hesselberth on wed 15 nov 00
Hi Ron,
See some comments below:
Ron Philbeck wrote:
Is this a stable,
>durable,safe glaze? How can I expect it to act in the bucket over
>time? (settling into a hard lump??) I am firing to cone 10 ,
>reduction. The ash is from my wood heater mostly poplar and oak with
>some pine.
>
>Nuka type
>G-200 60
>Ash 50
>Silica 40
>
>Opaque white with lighter color on edges and breaks.
>
I used a generic analysis for wood ash and find this quite low in silica
(1.927) and alumina (0.154). There is nothing in it that is really going
to hurt anyone, but it will not be very durable. That is if my wood ash
analysis is anywhere close to what you actually have.
>
>I also liked the following modification of a Phil Rogers high silica
>glaze that was similar in color and surface to the Nuka type above.
>
>Ash 50
>Silica 40
>G-200 30
>Cornwallstone 30
>RIO 1
>
Ditto this one. Silica is 2.0 and alumina 0.146. Not durable at all.
But it doesn't contain anything that might be considered toxic.
The problem with glazes like this (in addition to not being durable in
their own right) is that pretty soon someone wonders what it would look
like with, say, 5% copper and finds it looks pretty good. Then you will
have a glaze that vinegar will suck the color right out of.
I would recommend you find glazes with silica about 2.5-4.0 and alumina
above 0.25-0.45 if you are going to use them on functional work. Good
luck. John
>Thanks in advance for any help or suggestions.
>Ron Philbeck
>Shelby, NC
>ronpots@shelby.net
>www.cclay.com/rphilbeck
>
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John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"It is, perhaps, still necessary to say that the very best glazes cannot
conceal badly shaped pots..." David Green, Pottery Glazes
Ron Philbeck on wed 15 nov 00
I've been testing ash glazes most of the summer trying to come up with
some ash celadons. I've had little luck there, but did like some of the
high silica plus ash tests that I ran.
I have tested the following on small tiles in several firings and gotten
consistent results. I would like to move on to testing a larger batch,
but thought I'd get some feedback before I did so. Is this a stable,
durable,safe glaze? How can I expect it to act in the bucket over
time? (settling into a hard lump??) I am firing to cone 10 ,
reduction. The ash is from my wood heater mostly poplar and oak with
some pine.
Nuka type
G-200 60
Ash 50
Silica 40
Opaque white with lighter color on edges and breaks.
I also liked the following modification of a Phil Rogers high silica
glaze that was similar in color and surface to the Nuka type above.
Ash 50
Silica 40
G-200 30
Cornwallstone 30
RIO 1
Thanks in advance for any help or suggestions.
Ron Philbeck
Shelby, NC
ronpots@shelby.net
www.cclay.com/rphilbeck
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