Paul Steege on wed 14 nov 07
I am puzzled by something happening with an ash glaze I have just =
started using. I have been experimenting with coloring it different =
ways, and I have come up with a blue version and a green version I am =
pleased with. Both were mixed at the same time using the same base =
glaze formula. The base is: 52% unwashed wood ash, 25% custer feldspar, =
15% epk, and 8% ball clay. The green contains an addition of 0.5% Mason =
stain 6223. The blue contains additions of 0.5% cobalt oxide, 0.5% red =
iron oxide, 2% copper carb., and 1% rutile. A month after mixing them, =
I went to glaze some pots and found that the green glaze had not changed =
significantly in terms of how thick it applied to the bisque, but the =
blue glaze required an addition of about a gallon and a half of water =
(to a full five gallon batch) in order to get the right thickness. Two =
days later I went to glaze some more pieces and found it thickened =
again. I had to add two more quarts of water to get it the right =
thickness. Now it takes forever to dry on my pots. Why such a =
difference in consistency between the two glazes? What can be done to =
correct the thickening issue?
Paul Steege
Nevada City, CA
Richard Aerni on thu 15 nov 07
Paul,
This is a relatively common problem when you are using unwashed ash. The
alkaline solubles tend to flocculate (thicken) the glaze to a puddinglike
consistency over time. I add Darvon 7, a couple of tablespoons to a 2000
gram dry batch, and it will keep the glaze stable for a long period of time.
Adding more water to a flocculated ash glaze will totally throw your
quality control out the window. I would think that you might as well pitch
it and mix a new batch, using a deflocculant to stabilize it. I can't think
of a reason in the world why the one glaze would thicken and the other not.
I don't use Mason stains in my ash glazes, but use all the other colorants
you mentioned, in a fairly similar recipe, and have never noticed any of
them having any effect on thickness.
Good luck,
Richard Aerni
Rochester, NY
On Wed, 14 Nov 2007 23:04:12 -0800, Paul Steege
wrote:
>I am puzzled by something happening with an ash glaze I have just started
using. I have been experimenting with coloring it different ways, and I
have come up with a blue version and a green version I am pleased with.
Both were mixed at the same time using the same base glaze formula. The
base is: 52% unwashed wood ash, 25% custer feldspar, 15% epk, and 8% ball
clay. The green contains an addition of 0.5% Mason stain 6223. The blue
contains additions of 0.5% cobalt oxide, 0.5% red iron oxide, 2% copper
carb., and 1% rutile. A month after mixing them, I went to glaze some pots
and found that the green glaze had not changed significantly in terms of how
thick it applied to the bisque, but the blue glaze required an addition of
about a gallon and a half of water (to a full five gallon batch) in order to
get the right thickness. Two days later I went to glaze some more pieces
and found it thickened again. I had to add two more quarts of water to get
it the right thickness. Now it takes forever to dry on my pots. Why such a
difference in consistency between the two glazes? What can be done to
correct the thickening issue?
>
>Paul Steege
>Nevada City, CA
Chaeli Sullivan on thu 15 nov 07
Paul
Just out of curiosity, what cone did you fire this glaze to? And did you fire it in oxidation? Or reduction?
Thanks
Chae
http://claygallimaufry.blogspot.com
Paul Steege wrote:
I am puzzled by something happening with an ash glaze I have just started using. I have been experimenting with coloring it different ways, and I have come up with a blue version and a green version I am pleased with. Both were mixed at the same time using the same base glaze formula. The base is: 52% unwashed wood ash, 25% custer feldspar, 15% epk, and 8% ball clay. The green contains an addition of 0.5% Mason stain 6223. The blue contains additions of 0.5% cobalt oxide, 0.5% red iron oxide, 2% copper carb., and 1% rutile. A month after mixing them, I went to glaze some pots and found that the green glaze had not changed significantly in terms of how thick it applied to the bisque, but the blue glaze required an addition of about a gallon and a half of water (to a full five gallon batch) in order to get the right thickness. Two days later I went to glaze some more pieces and found it thickened again. I had to add two more quarts of water to get it the right thickness.
Now it takes forever to dry on my pots. Why such a difference in consistency between the two glazes? What can be done to correct the thickening issue?
Paul Steege
Nevada City, CA
______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, or change your
subscription settings here: http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
---------------------------------
Never miss a thing. Make Yahoo your homepage.
Dannon Rhudy on thu 15 nov 07
Wood ash glazes made with unwashed ash often gel,
or have other problems over time. I recommend that
you only mix as much as you need for a glaze session.
Adding water simply thins the glaze; the gel occurs
when various substances leach from the unwashed ash.
Don't know why one might and one might not, but in
general ash glazes do not keep long-term. In my
experience.
regards
Dannon Rhudy
Mark Issenberg on thu 15 nov 07
Hey Paul, when I mix ashglaze I mix small batches. My blue ash and my green
ash dont seem to get as thick as my 50/50 redart and ash glaze. I usually dump
my 50/50 batch if im not going to use it for days..But that's just what I
have found using ash glaze.
My $.02
Mark
Potters Council Member
lookoutmountainpottery.com
Rising Fawn Georgia
PS ,, It rained yesterday ,maybe because our governor prayed for it,,no
kidding,it was in the paper
it filled my 330 gallon rain barrel,no kidding
************************************** See what's new at http://www.aol.com
Paul Steege on fri 16 nov 07
Thanks for your help, Mark, Dannon, John, Tom, Richard. Will try the =
Darvan. Chae, I fire to cone 10 reduction.
Lee Love on fri 16 nov 07
On Thu, 15 Nov 2007 17:09:27 EST, Mark Issenberg wrote:
>ash dont seem to get as thick as my 50/50 redart and ash glaze. I usually dump
> my 50/50 batch if im not going to use it for days..But that's just what I
>have found using ash glaze.
This is why I wash my wood ash. Then you don't waste so much.
If you really want the solubles, decant the first wash of the ash and
save it. Dip your pots is the solution, let it dry and then glaze it.
--
Lee In Mashiko, Japan
Bill Merrill on fri 16 nov 07
I have kept wood ash glazes wet over long periods of time without any
problems. I use apple wood ash that is completely burned into a fluffy
light ash. There are no carbon pieces etc. In the ash I use. My son
uses wood to fire his wood fired oven and the ash is considerable and
easy to find. Look for a restaurant in your area that has wood fired
ovens. Maybe they will save the ash for you if you provide a large
galvanized container with a lid. I have got ash from other sources that
was still contaminated with small unburned pieces of wood. I put this
ash on a kiln shelf at the top of an electric kiln. I put about 2
" thick layer. I then heated the kiln to 1200 degrees and then left the
lid of the kiln open about an inch. If you calcine the ash too high in
temperature the ash will stick together in chunks, because the ash is
sinstering together like the particles in a clay.
The person to ask about wood ash is Richard Aerni.
Bill
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Dannon
Rhudy
Sent: Thursday, November 15, 2007 2:30 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: ash glaze quandary
Wood ash glazes made with unwashed ash often gel,
or have other problems over time. I recommend that
you only mix as much as you need for a glaze session.
Adding water simply thins the glaze; the gel occurs
when various substances leach from the unwashed ash.
Don't know why one might and one might not, but in
general ash glazes do not keep long-term. In my
experience.
regards
Dannon Rhudy
________________________________________________________________________
______
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, or change your
subscription settings here: http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots2@visi.com
Lee Love on sat 17 nov 07
On 11/16/07, Richard Aerni wrote:
> I can't think
> of a reason in the world why the one glaze would thicken and the other not.
It has copper carbonate in it. It is possible that it acts as
some kind of electrolyte in the blue glaze.
--
Lee in Minneapolis, Minnesota USA
"Men are born ignorant, not stupid. They are made stupid by
education." -- Bertrand Russell
| |
|
