Paul Lewing on sun 14 nov 04
on 11/14/04 6:09 AM, Sue Beach at sbeach@IQUEST.NET wrote:
> I fire ^6 electric.
>
> 1) I read in one of Susan Peterson's books that you could mix native clay &
> wood ash 50-50 as a start toward developing an ash glaze. I'm assuming that
> one
> would adjust the ratio of ash to clay up & down based on the results of the
> initial test. I am thinking of using an Albany slip sub for one & perhaps Red
> Art for another. Has anyone tried this that would like to share their
> results?
Susan, at cone 6 you're not likely to get a melted glaze with equal parts
ash and clay. Ms. Peterson is talking about cone 10, at which that's a
reasonable starting point. Wood ash has a lot of silica in it, so it's very
refractory, although ashes vary widely. A better starting point would
probably be 1/3 each ash, clay, and flux of some kind (Neph Sy, frit,
Gerstley Borate or an equivalent). And the Albany will probably melt better
than the Redart.
>
> 2) I read/heard/was told (I forget) that one could just add a % of wood ash
> to
> glazes they already use. What % would you suggest starting with? Should the
> flux ingredient in the original recipe be reduced by the amount of wood ash?
> Or
> should the wood ash be an add on ingredient above the original recipe?
I've done this. Start with a pretty shiny or fluid glaze, as the ash will
stiffen it up. Do a line blend, adding maybe 5% at a time. I settled on
20% ash added to a clear glaze when I did it. It still didn't look like
what you'd call an ash glaze, but it was definitely noticeable, and I used
it for many years. It added a really nice grey tone and a lot of very
variegated speckles.
Happy testing,
Paul Lewing, Seattle
Sue Beach on sun 14 nov 04
I'm getting ready to mix some glaze tests I've been thinking about & had a
couple of questions for the glaze experts. I fire ^6 electric.
1) I read in one of Susan Peterson's books that you could mix native clay &
wood ash 50-50 as a start toward developing an ash glaze. I'm assuming that one
would adjust the ratio of ash to clay up & down based on the results of the
initial test. I am thinking of using an Albany slip sub for one & perhaps Red
Art for another. Has anyone tried this that would like to share their results?
2) I read/heard/was told (I forget) that one could just add a % of wood ash to
glazes they already use. What % would you suggest starting with? Should the
flux ingredient in the original recipe be reduced by the amount of wood ash? Or
should the wood ash be an add on ingredient above the original recipe?
Thanks.
Sue Beach
Potters Council Member
Muncie, IN
who will be testing these glazes in small bowls - insides only
Ivor and Olive Lewis on mon 15 nov 04
Dear Sue Beach,
IF you are running tests in your production ^6 Electric kiln I would
suggest several tiles with line blends covering the range 1-90=> 90-10
(not much point doing the end members). Yes, Native clay with your
ash, but also try your favourite spars, ball clays and a good kaolin
and if you have them.
If nothing worthwhile comes out of that I would go straight on to Quad
blends with four materials rather than try to randomly "tweak" what
may be a promising example from one of these early tests. Two ways to
do this. Either use Ian Curries grid system or use the traditional
selection of four, A melter (Your ash), a stiffener (your native
clay), a glass former (straight silica) and an auxiliary (Could be a
melter such as a frit or a boron compound or something to influence
viscosity such as an alkali earth) and do some 6*6 tiles. If you get
that far I can let you have the matrix for 6*6 where every sample has
four ingredients.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
----- Original Message -----
From: "Sue Beach"
To:
Sent: Monday, 15 November 2004 12:39
Subject: Wood Ash in Glazes - a couple of questions
> I'm getting ready to mix some glaze tests I've been thinking about &
had a
> couple of questions for the glaze experts. I fire ^6 electric.
>
> 1) I read in one of Susan Peterson's books that you could mix
native clay &
> wood ash 50-50 as a start toward developing an ash glaze. I'm
assuming that one
> would adjust the ratio of ash to clay up & down based on the results
of the
> initial test. I am thinking of using an Albany slip sub for one &
perhaps Red
> Art for another. Has anyone tried this that would like to share
their results?
>
> 2) I read/heard/was told (I forget) that one could just add a % of
wood ash to
> glazes they already use. What % would you suggest starting with?
Should the
> flux ingredient in the original recipe be reduced by the amount of
wood ash? Or
> should the wood ash be an add on ingredient above the original
recipe?
>
> Thanks.
>
> Sue Beach
> Potters Council Member
> Muncie, IN
>
> who will be testing these glazes in small bowls - insides only
>
>
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brian on mon 15 nov 04
On 14/11/04 Sue wrote ....
> I read/heard/was told (I forget) that one could just add a % of wood ash to
>glazes they already use. What % would you suggest starting with?
Sue
If you are interested in non functional glazes or textures you might be
interested in the article archived on my site. the illustrations
show the effects of mixing unwashed wood ash with several other
materials using simple volume measurements. Theyb were mostly
achieved at the cone 6 level in electric kilns.
http://www.gartside.info/woodashchart.htm
--
Brian Gartside
http://www.gartside.info
Pukekohe, New Zealand
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