Lynne Antone on fri 22 oct 99
Hi gang,
Thanks for all of the suggestions on curing my pottery bloating problems.
Will let you know how things work out.
Now onto another dilema. I have one glaze which is forming crystals. I just
mixed up a new batch approx. three weeks ago and when I went to add the new
glaze to the small amount left from the last mix, I noticed the crystals in
the top of the leftover mix. They are in two shapes. One is a rectangular
shape, approx. .25" thick and .5" long by .25" wide and also mostly six
sided, very flat ones, just beautiful. My husband dropped some off to a
friend and he said it was a first for him, but had no idea just by looking
what was happening. He questioned the use of salts, but says it doesn't look
like we used any. The new batch is now forming the same crystals, in a much
shorter time.
Here is the recipe:
Deep Purple---10#s
cone 6
Gerst. Borate---355.8
Whiting---507.6
Neph. Sy---606.0
Flint---1380.5
Custer Spar (Kingman)---1140.1
Lithium carb---154.0
Magnesium Carb---72.3
Cobalt Carb---25.7
Tin Oxide---205.3
Chrome oxide---7.3
Bentonite---85.5
Total 4540.0
I got this from a couple of posts a couple of years ago and really like it.
It comes out a nice deep purple breaking light blue in cone 6 oxidation and a
sky blue in reduction. When I mix with my paint mixer and drill, it gets
almost foamy. After I dip the pots in, I have a lot of pits to smooth out,
but have also fired without smoothing them out and they fire to a nice
finish. I use rain water for my liquid and keep the Specific Gravity to
around 1.4.
What's happening? I don't want to have to strain this glaze every time I use
it. I was told after straining to heat the crystals in water to remelt them
and add back to the mix, so at least I can get the same glaze. But strain
every time?
Thanks for any help, as always,
Lynne Antone
Olympia WA
Pottery by Dai on sat 23 oct 99
Hi, Lynne - A fellow potter says she has trouble with crystals in a glaze of
hers that also contains lithium---especially if it's cool or cold where
she's storing it. But, not being intot the science of glazes, I don't know
how you'd get rid of the lithium (if that's the problem) and still make the
glaze work. Do you have the recipe for the Deep Purple ^6 in "percent"
form? TIA.
Dai Scott in Kelowna, B.C., where we were treated to Northern Lights while
soaking in the hot tub last night.
>Deep Purple---10#s
>cone 6
>
>Gerst. Borate---355.8
>Whiting---507.6
>Neph. Sy---606.0
>Flint---1380.5
>Custer Spar (Kingman)---1140.1
>Lithium carb---154.0
>Magnesium Carb---72.3
>Cobalt Carb---25.7
>Tin Oxide---205.3
>Chrome oxide---7.3
>Bentonite---85.5
>Total 4540.0
Bob Freitas on sat 23 oct 99
Hi to All,
Lynne,
You may have calcium crystals, which can form both somewhat rectangular crystals
and the six-sided flat ones you mentioned. Hard water is usually the main
culprit, tho' sulfides may be a catalyst. Since your in Olympia, a volcanic
area, there may be enough sulfides to do it, 'course, if your using rainwater,
there shouldn't be any problem. I had the same problem with a glaze mixed in
Calistoga, California, using well water. The crystals settled in a two inch
layer in the bottom of the bucket over night! Took a major portion of the
calcium out. Warm water may not solve the problem. Not sure what to tell you to
do, we tried water softener, but that adds things to the glaze that must be
compensated for.
Sorry this couldn't be of more help,
Bob
central California, where summer doesn't want to leave!
Lynne Antone wrote:
> ----------------------------Original message----------------------------
> Hi gang,
>
> Thanks for all of the suggestions on curing my pottery bloating problems.
> Will let you know how things work out.
>
> Now onto another dilema. I have one glaze which is forming crystals. I just
> mixed up a new batch approx. three weeks ago and when I went to add the new
> glaze to the small amount left from the last mix, I noticed the crystals in
> the top of the leftover mix. They are in two shapes. One is a rectangular
> shape, approx. .25" thick and .5" long by .25" wide and also mostly six
> sided, very flat ones, just beautiful. My husband dropped some off to a
> friend and he said it was a first for him, but had no idea just by looking
> what was happening. He questioned the use of salts, but says it doesn't look
> like we used any. The new batch is now forming the same crystals, in a much
> shorter time.
>
> Here is the recipe:
>
> Deep Purple---10#s
> cone 6
>
> Gerst. Borate---355.8
> Whiting---507.6
> Neph. Sy---606.0
> Flint---1380.5
> Custer Spar (Kingman)---1140.1
> Lithium carb---154.0
> Magnesium Carb---72.3
> Cobalt Carb---25.7
> Tin Oxide---205.3
> Chrome oxide---7.3
> Bentonite---85.5
> Total 4540.0
>
> I got this from a couple of posts a couple of years ago and really like it.
> It comes out a nice deep purple breaking light blue in cone 6 oxidation and a
> sky blue in reduction. When I mix with my paint mixer and drill, it gets
> almost foamy. After I dip the pots in, I have a lot of pits to smooth out,
> but have also fired without smoothing them out and they fire to a nice
> finish. I use rain water for my liquid and keep the Specific Gravity to
> around 1.4.
>
> What's happening? I don't want to have to strain this glaze every time I use
> it. I was told after straining to heat the crystals in water to remelt them
> and add back to the mix, so at least I can get the same glaze. But strain
> every time?
>
> Thanks for any help, as always,
> Lynne Antone
> Olympia WA
Michael Banks on sat 23 oct 99
It is likely that the crystals result from reactions between the soluble
components of the gerstley borate and one or more of the more soluble
carbonates in the glaze, most likely the lithium carb. For example, Li ions
from the lithium carb could replace the Ca ions in the colemanite portion of
the gerstley borate, to form lithium borate and calcium carbonate (calcite).
The calcite will precipitate as it is very insoluble, and may in fact be
your flat hexagonal crystals. These cation swapping reactions between
soluble salts move in the direction producing the least soluble salt, as it
is constantly removed by precipitation.
Other likely possible crystals are borates less soluble than ulexite or
colemanite (the two common constituents of gerstley borate). I don't have
solubility data for lithium borate (one possible product), perhaps another
clayarter can provide this?
Positive ID of the crystals could be determined by a mineralogist, or
chemist, or XRD analysis. As a first step try putting the crystals in dilute
hydrochloric acid and see if they fizz.
Michael Banks,
Nelson,
New Zealand
> ----------------------------Original message----------------------------
> Hi gang,
>
> Thanks for all of the suggestions on curing my pottery bloating problems.
> Will let you know how things work out.
>
> Now onto another dilema. I have one glaze which is forming crystals. I
just
> mixed up a new batch approx. three weeks ago and when I went to add the
new
> glaze to the small amount left from the last mix, I noticed the crystals
in
> the top of the leftover mix. They are in two shapes. One is a rectangular
> shape, approx. .25" thick and .5" long by .25" wide and also mostly six
> sided, very flat ones, just beautiful. My husband dropped some off to a
> friend and he said it was a first for him, but had no idea just by looking
> what was happening. He questioned the use of salts, but says it doesn't
look
> like we used any. The new batch is now forming the same crystals, in a
much
> shorter time.
>
> Here is the recipe:
>
> Deep Purple---10#s
> cone 6
>
> Gerst. Borate---355.8
> Whiting---507.6
> Neph. Sy---606.0
> Flint---1380.5
> Custer Spar (Kingman)---1140.1
> Lithium carb---154.0
> Magnesium Carb---72.3
> Cobalt Carb---25.7
> Tin Oxide---205.3
> Chrome oxide---7.3
> Bentonite---85.5
> Total 4540.0
>
> I got this from a couple of posts a couple of years ago and really like
it.
> It comes out a nice deep purple breaking light blue in cone 6 oxidation
and a
> sky blue in reduction. When I mix with my paint mixer and drill, it gets
> almost foamy. After I dip the pots in, I have a lot of pits to smooth out,
> but have also fired without smoothing them out and they fire to a nice
> finish. I use rain water for my liquid and keep the Specific Gravity to
> around 1.4.
>
> What's happening? I don't want to have to strain this glaze every time I
use
> it. I was told after straining to heat the crystals in water to remelt
them
> and add back to the mix, so at least I can get the same glaze. But strain
> every time?
>
> Thanks for any help, as always,
> Lynne Antone
> Olympia WA
>
zahidi neale on sun 24 oct 99
These crystals form in my leftover Raku glazes that contain gerstley borate.
It takes about a week, depending on the temperature glazes are subjected to.
I use them after straining them out. If you sprinkle them on the top of raw
bisque ware and raku fire, the crystal melts into a little shiny spot. Kewl.
But the only solution I can think of is to mix SMALL batches and use them
up, or maybe store the glaze refrigerated????
Zee in LA
-----Original Message-----
From: Lynne Antone
To: CLAYART@LSV.UKY.EDU
Date: Friday, October 22, 1999 9:31 AM
Subject: Glaze crystals
>----------------------------Original message----------------------------
>Hi gang,
>
>Thanks for all of the suggestions on curing my pottery bloating problems.
>Will let you know how things work out.
>
>Now onto another dilema. I have one glaze which is forming crystals. I just
>mixed up a new batch approx. three weeks ago and when I went to add the new
>glaze to the small amount left from the last mix, I noticed the crystals in
>the top of the leftover mix. They are in two shapes. One is a rectangular
>shape, approx. .25" thick and .5" long by .25" wide and also mostly six
>sided, very flat ones, just beautiful. My husband dropped some off to a
>friend and he said it was a first for him, but had no idea just by looking
>what was happening. He questioned the use of salts, but says it doesn't
look
>like we used any. The new batch is now forming the same crystals, in a much
>shorter time.
>
>Here is the recipe:
>
>Deep Purple---10#s
>cone 6
>
>Gerst. Borate---355.8
>Whiting---507.6
>Neph. Sy---606.0
>Flint---1380.5
>Custer Spar (Kingman)---1140.1
>Lithium carb---154.0
>Magnesium Carb---72.3
>Cobalt Carb---25.7
>Tin Oxide---205.3
>Chrome oxide---7.3
>Bentonite---85.5
>Total 4540.0
>
>I got this from a couple of posts a couple of years ago and really like it.
>It comes out a nice deep purple breaking light blue in cone 6 oxidation and
a
>sky blue in reduction. When I mix with my paint mixer and drill, it gets
>almost foamy. After I dip the pots in, I have a lot of pits to smooth out,
>but have also fired without smoothing them out and they fire to a nice
>finish. I use rain water for my liquid and keep the Specific Gravity to
>around 1.4.
>
>What's happening? I don't want to have to strain this glaze every time I
use
>it. I was told after straining to heat the crystals in water to remelt them
>and add back to the mix, so at least I can get the same glaze. But strain
>every time?
>
>Thanks for any help, as always,
>Lynne Antone
>Olympia WA
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