Sandra K. Tesar on tue 28 apr 98
Does a glaze have alife? I have some glazes Ihave come into that are in
buckets dated '94 - a raku white crackle, a raku "reddish-green" and a
lemon luster. THe results have been varied and inconsistant with the
samples I have run - should I dispose of it or is there someway to
reawaken it to consistancy? Any information would be appreciated. I also
came into several gallon jugs of ^6 glazes which have not been touched in
10 years...and are not rock hard...is it worth while reconstituting these
to play with?
TIA
Sandra Tesar on Keel Mountain
sashart@juno.com
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Mudnjoy on wed 29 apr 98
In a message dated 98-04-28 08:23:54 EDT, you write:
> I also came into several gallon jugs of ^6 glazes which have not been
touched in
> 10 years...and are not rock hard...is it worth while re constituting these
> to play with?
Anything starting with the dirt in your yard is great to play with. When I
glaze I wash everything off in a bucket, let it settle, pour off the water
run, screen it & test the results. I usually test some with clear over, some
dull glazes come to life under clear. You'd be surprised with what you get.
One potter I talked into using this method "harvested" in a year about 10
gallons of a lovely blue green that she used on a large mural. This is a mix
of glazes I do not consider them food safe but great on exteriors tile &
sculpture. Think of the materials you are keeping out of the local water
tables & no disposal hassles. Best of all every kiln unloading has a
surprise, well ...one you can look forward to. Joy In Tucson
David Hendley on wed 29 apr 98
Sandra,
I moved, and put my studio in storage for 6 years.
The glazes were left, ready to use, in 5 gallons buckets.
Six years later, they looked fine, and worked fine.
I still have some of those buckets of glaze (glazes I don't use
very often, but like to have around), and we're now going on
14 years, and they are still fine.
These are all ^10 glazes, containing the usual common ingredents.
Several include gerstley borate, known to be slightly soluable, in small
amounts.
What can it hurt to test what you have?
David Hendley
Maydelle, Texas
At 07:58 AM 4/28/98 EDT, you wrote:
>----------------------------Original message----------------------------
>Does a glaze have alife? I have some glazes Ihave come into that are in
>buckets dated '94 - a raku white crackle, a raku "reddish-green" and a
>lemon luster. THe results have been varied and inconsistant with the
>samples I have run - should I dispose of it or is there someway to
>reawaken it to consistancy? Any information would be appreciated. I also
>came into several gallon jugs of ^6 glazes which have not been touched in
>10 years...and are not rock hard...is it worth while reconstituting these
>to play with?
>
>TIA
>Sandra Tesar on Keel Mountain
>sashart@juno.com
>
>_____________________________________________________________________
>You don't need to buy Internet access to use free Internet e-mail.
>Get completely free e-mail from Juno at http://www.juno.com
>Or call Juno at (800) 654-JUNO [654-5866]
>
nick goodman on wed 29 apr 98
I have seen glazes change character in the bucket- one raku glaze had
crystals on the sides of the bucket and floating on top, but it did not
affect the final product. I have a friend who has redish ^5 glaze that
changed its color a bit over just a few months. I do not know why this
happens--can anyone else tell us?
Nick Goodman
goodhome@dunn.sbceo.k12.ca.us
Joyce Lee on thu 30 apr 98
Can a glaze be "old" at six months? That's how old my bucket of rutile
blue is and it definitely is no longer "blue" on any claybody. However,
the good news is that it no longer seems to "run" either. I still stick
a pot or two glazed from this bucket into every small load of shinos,
hoping for that unbelievably to-get-lost-in rutile look. I think I read
that rutile is likely "tan" in oxidation, so decided I wasn't really
reducing when I fired. Well, I am definitely in reduction in my latest
firings and still......rutile browns. It is a pretty glaze though.
Brown, tan, butterscotchy (I think in terms of food, I'm afraid) with
dabs of burgundy, dark goldy, and sorta' navy-bluey where it breaks. I'm
happy with it but would like my surreal blue back, too. I had ONE really
successful pot with the blue, and it sold at 8:01 a.m. at a Christmas
sale where the doors opened at 8:00. The photographer who took some
pre-sale publicity shots for our local newspaper bought it. The form
was very, very, very ordinary (as well as a little lumpy/dumpy) but
the glaze was extraordinary...in our stretch of the Mojave, anyway.
It was the ONLY successful pot from this glaze, true, but I still have
very successful remnants on several shelves that I can't quite bear to
vanquish. Any guesses as to what happened?
Joyce
In the Mojave getting ready to adios and go back to glazing shinos and
one or two rutile browns.
Tom Buck on thu 30 apr 98
Nick Goodman:
Your query about glaze changes on standing seems to suggest that
glaze ingredients should not follow usual chemical behaviour, namely,
undergo reaction where circumstances permit.
Many raw materials that we use in our glaze recipes are not
totally insoluble (ie, do not dissolve) but undergo slight changes when
placed in water, and some of these changes lead to new crystals (perhaps
new compounds) being formed.
One common problem faced by raku potters is the behaviour of
Gerstley Borate, a mineral from California that is mainly a blend of two
natural minerals/chemicals, namely, ulexite and colemanite. Ulexite is a
hydrated double salt of boric acid, NaCaB5O9.8H2O and colemanite is
hydrated calcium borate, 2CaO.3B2O3.5H20. Both these borate salts are
slightly soluble (moreso in warm/hot water) and release ions that will
subsequently react and form new crystals in the glaze slurry when it is
allowed to stand for sometime. Chief of such crystals is probably borax,
sodium borate decahydrate, Na2O.2B2O3.10H2O, with sodium carbonate
crystals also a likelihood.
When this happens the glaze slurry becomes non-uniform and will
not truly represent the glaze recipe on the unfired pot. Results become
quite unpredictable.
A similar effect can occur with raw materials that have
substantially different particle densities so that one settles out rapidly
and makes the slurry non-uniform.
There is also an effect of materials that dissolve in the water
and stay as such, ie, dissolved solids, and these solutes are carred into
the pores of a soft-bisqued pot, and can then be deposited in the pores
when the water departs. In some cases, these misplaced chemicals can
drastically affect the fired pot.
One can minimize these effects by using, as Tony Hansen advocates,
as much kaolin as possible in the recipe, and in best case to form a gel
that permits a uniform glaze mix and coat on the pot. Perhaps Tony
will elaborate on this effect.
Tom Buck ) tel:
905-389-2339 & snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
On Wed, 29 Apr 1998, nick goodman wrote:
> ----------------------------Original message----------------------------
> I have seen glazes change character in the bucket- one raku glaze had
> crystals on the sides of the bucket and floating on top, but it did not
> affect the final product. I have a friend who has redish ^5 glaze that
> changed its color a bit over just a few months. I do not know why this
> happens--can anyone else tell us?
>
> Nick Goodman
> goodhome@dunn.sbceo.k12.ca.us
>
MLCeramics on fri 1 may 98
I am wondering what the effect of glazes freezing and then defrosting is.
My glazes froze several times when I moved my studio in the past few years. I
recently remixed most of them from scratch because I figure that they probably
had changed a lot by now. My glazes are low-fire and most contain gerstley
borate. After reading Tom's post about Gerstly Borate changing chemical
composition I am glad I remixed them. Meg
Olivia T Cavy on fri 1 may 98
Tom,
Thanks for your explanation. Last November I used a bucket of glaze over
a year old that had been sitting in a cold, freezing basement for several
months. I thought I had mixed it well (but I was cold, too) and the pots
came out with very uneven color (so I doubt I mixed it as well as I
thought). I don't have the glaze here but it may well have contained
gerstley borate.
However, one of the pots glazed was a mug with a smiley face carved on
the outside. (And if you thought Kokopelli was over sold, think of that
smiley face!) The color in the glaze was considerably lighter at the top
of the mug, gradually darkening towards the bottom of the mug.
I ended up with a smiley face with a 5 o'clock shadow which really makes
everyone who sees it smile.
Now I understand why it happened.
Bonnie
Bonnie D. Hellman
Pittsburgh, PA
work email: oliviatcavy@juno.com
home email: mou10man@sgi.net
On Thu, 30 Apr 1998 07:45:31 EDT Tom Buck writes:
>----------------------------Original
>message----------------------------
>Nick Goodman:
> Your query about glaze changes on standing seems to suggest
>that
>glaze ingredients should not follow usual chemical behaviour, namely,
>undergo reaction where circumstances permit.
> Many raw materials that we use in our glaze recipes are not
>totally insoluble (ie, do not dissolve) but undergo slight changes
>when
>placed in water, and some of these changes lead to new crystals
>(perhaps
>new compounds) being formed.
> One common problem faced by raku potters is the behaviour of
>Gerstley Borate, a mineral from California that is mainly a blend of
>two
>natural minerals/chemicals, namely, ulexite and colemanite. Ulexite is
>a
>hydrated double salt of boric acid, NaCaB5O9.8H2O and colemanite is
>hydrated calcium borate, 2CaO.3B2O3.5H20. Both these borate salts are
>slightly soluble (moreso in warm/hot water) and release ions that will
>subsequently react and form new crystals in the glaze slurry when it
>is
>allowed to stand for sometime. Chief of such crystals is probably
>borax,
>sodium borate decahydrate, Na2O.2B2O3.10H2O, with sodium carbonate
>crystals also a likelihood.
> When this happens the glaze slurry becomes non-uniform and
>will
>not truly represent the glaze recipe on the unfired pot. Results
>become
>quite unpredictable.
> A similar effect can occur with raw materials that have
>substantially different particle densities so that one settles out
>rapidly
>and makes the slurry non-uniform.
> There is also an effect of materials that dissolve in the
>water
>and stay as such, ie, dissolved solids, and these solutes are carred
>into
>the pores of a soft-bisqued pot, and can then be deposited in the
>pores
>when the water departs. In some cases, these misplaced chemicals can
>drastically affect the fired pot.
> One can minimize these effects by using, as Tony Hansen
>advocates,
>as much kaolin as possible in the recipe, and in best case to form a
>gel
>that permits a uniform glaze mix and coat on the pot. Perhaps Tony
>will elaborate on this effect.
>
>Tom Buck ) tel:
>905-389-2339 & snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
>(westend Lake Ontario, province of Ontario, Canada).
>
>On Wed, 29 Apr 1998, nick goodman wrote:
>
>> ----------------------------Original
>message----------------------------
>> I have seen glazes change character in the bucket- one raku glaze
>had
>> crystals on the sides of the bucket and floating on top, but it did
>not
>> affect the final product. I have a friend who has redish ^5 glaze
>that
>> changed its color a bit over just a few months. I do not know why
>this
>> happens--can anyone else tell us?
>>
>> Nick Goodman
>> goodhome@dunn.sbceo.k12.ca.us
>>
>
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Sandra K. Tesar on sat 2 may 98
I want to thank the many responses I received regarding old raku glazes
and oold glazes in general. I dumped the raku glaze, remixed the recipe
and got excellent results. The other glazes are on hold while I attend to
a show schedule. Thanks again.
Sandra on Keel Mountain
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lili krakowski on mon 1 feb 10
The one repeated warning about old glazes, as well as stains, is that =3D
many contain ingredients--such as lead, and antimony-- which we no =3D
longer use. Even if you wear your mask, and use rubber gloves when =3D
handling the stuff, and have a vent on your kiln, the fumes do get into =3D
the brick, and are considered a safety issue, as they will re-vaporize. =
=3D
I know NOTHING about the relative dangers, but would check the =3D
manufacturer for content info.
Even in the old days glazes had "stuff" added to them to make them =3D
smoother, easier to apply and so on. If you decide to use them, see =3D
below.
If no one has suggested it yet, add plenty of warm water to the dried up =
=3D
glazes and let sit a generous week. Much of the problem one has with =3D
reclaiming old glazes is from lack of patience.
Stir every few days, just a bit, and after a week or so, sieve though a =3D
regular kitchen sieve YOU KEEP FOR THE STUDIO. Some material may be =3D
like little rocks, which you need to grind or pulverize. When all is =3D
done strain though a regular glaze sieve.
Lili Krakowski
Be of good courage
Randall Moody on mon 1 feb 10
On Mon, Feb 1, 2010 at 1:40 PM, lili krakowski wro=
te:
> The one repeated warning about old glazes, as well as stains, is that man=
y
> contain ingredients--such as lead, and antimony-- which we no longer use.
> Lili Krakowski
> Be of good courage
>
How old are we talking?!? When was the last year that glazes contained lead
and antimony? I seriously doubt that the average glaze on the shelf of your
local potter supply, even if considered "out of date" is old enough to
contain lead or antimony without a very obvious warning on the label.
--
Randall in Atlanta
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