The Kings on tue 13 mar 01
I send this call for help with some trepidation. I am a fledgling =
potter dipping into glazes. I have limited with background in =
glazemaking workshops. My technical background is limited. Currently =
I am working with lowfire 04 terracotta clay. I am asking for help from =
experienced potters. Here is my problem: I discovered about .5 cm =
hexagonal crystals in my 100 g test glaze batches after sitting for =
about a month. I called my supplier about this problem. Basicly they =
thought it was funny. Said they never heard about that happening before. =
Needless to say that doesn't help. The only difference that I noticed =
in my recipe is that it calls for Gerstley Borate and I replaced it with =
Lagunua Borate since I have discovered I can no longer get it. Now, I =
have made other batches in the past with some Gerstley that I had on =
hand. I did not have the crystal problem. Thus, does it have something =
to do with the new borate? Most importanly, what do I do? The =
following is the Satin Matt Glaze 04 that I am having trouble with:
Gerstley Borate 38g
Lithium carbonate 10
Nepheline Syenite 5
EPK Kaolin 5
flint 42
plus bentonite 1%=20
color variations (I use mason stains 3-6%)
I do have a second question. I noticed that my matt has more shine =
using the new borate. I'm not complaining. I don't know enough to do =
that. I just want to know what to do.
This is my matt recipe=20
NCMatt 04
EPK Kaolin 16
Frit 3124 32
Gerstley Borate 32
Dolmite 20
I use oxides and carbonates to color this.
Oh yes, I have not noticed the crystal problem in the Matt glaze.
Thank you ahead of time to anyone that can be of help.
Confused but hopeful,
Kathleen King
Cindy Strnad on tue 13 mar 01
Hi, Kathleen.
This is a lot of lithium. I assume it's a decorative glaze--probably very
pretty. It's funny your supplier reacted to your problem by laughing and
saying he'd never heard of such a thing. I've never had it happen to me, but
from other posts to the list, it's apparently fairly common.
The crystals come from the combination of boron (from the Laguna Borate) and
lithium. According to other posts I've seen on this subject, they're
probably lithium crystals. Sieve them out, then, if you like, dissolve them
in a bit of hot water and add them back. They probably don't add up to
enough lithium to alter your glaze a lot if you just discard them, so you
might try the glaze without them.
Something about the high boron content causes the lithium to precipitate out
and form crystals. I don't know why you didn't see them before, but maybe
there were different conditions at that time in your storage area, or maybe
the Laguna Borate is just more favorable to crystal formation in this glaze.
As for the matte glaze, you might try it with a bit less Laguna Borate. The
new formulation is, apparently, melting your glaze better than the old one.
Try the glaze with maybe 15% Laguna, then 20%, 25%, and so on. Choose the
best test to try on a larger piece and see what you get.
I'm assuming this is not a functional glaze, as a low-fired matte of this
type generally would not be suitable for functional work.
I don't do a lot of low-fire work, but I have some posts on low-fire glazes
(which don't contain Gerstley) saved. If you'd like to try some new recipes,
contact me privately at earthenv@gwtc.net and I'll gladly forward them to
you. Meanwhile, Tony Hansen has a nice article on Majolica, and I believe
it's available in the education section of http://www.digitalfire.com .
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Richard Boggs on tue 13 mar 01
I too am getting crystals in a glaze that formerly did not! I also subbed=
Laguna for Gertsley. This glaze was mixed about two weeks ago. I fired a=
nyway and the crystals did show up as little brown runny spots. So far it=
seems that Laguna's does alter certain glazes now if someone can tell us=
why?
Thanks
Richard
The Kings wrote:
> I send this call for help with some trepidation. I am a fledgling pott=
er dipping into glazes. I have limited with background in glazemaking wo=
rkshops. My technical background is limited. Currently I am working wi=
th lowfire 04 terracotta clay. I am asking for help from experienced pott=
ers. Here is my problem: I discovered about .5 cm hexagonal crystals =
in my 100 g test glaze batches after sitting for about a month. I called=
my supplier about this problem. Basicly they thought it was funny. Said=
they never heard about that happening before. Needless to say that does=
n't help. The only difference that I noticed in my recipe is that it call=
s for Gerstley Borate and I replaced it with Lagunua Borate since I have =
discovered I can no longer get it. Now, I have made other batches in the=
past with some Gerstley that I had on hand. I did not have the crystal p=
roblem. Thus, does it have something to do with the new borate? Most im=
portanly, what do I do? The following is the Satin Matt Glaze 04 that I =
am having trouble with:
> Gerstley Borate 38g
> Lithium carbonate 10
> Nepheline Syenite 5
> EPK Kaolin 5
> flint 42
> plus bentonite 1%
> color variations (I use mason stains 3-6%)
>
> I do have a second question. I noticed that my matt has more shine usi=
ng the new borate. I'm not complaining. I don't know enough to do that.=
I just want to know what to do.
> This is my matt recipe
> NCMatt 04
> EPK Kaolin 16
> Frit 3124 32
> Gerstley Borate 32
> Dolmite 20
> I use oxides and carbonates to color this.
> Oh yes, I have not noticed the crystal problem in the Matt glaze.
> Thank you ahead of time to anyone that can be of help.
> Confused but hopeful,
> Kathleen King
>
> _______________________________________________________________________=
_______
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pcl=
ink.com.
Lorraine Pierce on tue 13 mar 01
Hi Meriam, this will not be the message you were hoping for, but since you
are back at the beginning so to speak, I strongly suggest using e few of the
excellent base glazes that contain NO gerstley borate, and proceed from
there. The Insight bases seem fool proof, as are Ron Roy's. Do you know how
to access them thru the archives? Lori in New Port Richey, Fl.
Louis Katz on tue 13 mar 01
Lithium Carbonate reacts with soluble boron in the glaze and lithium borate crystals appear. If you seive them out you will remove lithium and boron from your glaze which should have an impact on its look. This is an instance when grinding in a mortar and pestle and re adding them to the glaze may just work.
Louis
Mark Duerr on tue 13 mar 01
Just a thought. Perhaps the Laguna is mined near
a salt deposit. Take the crystals out and examine
them. Also see if the crystals disappear if the
solution is heated.
A couple of weeks ago someone wrote about a problem
they were having with GB. My first thought was,
send it all to me, that will solve my problem. . .
cheers,
mark duerr
>I too am getting crystals in a glaze that formerly did not! I also subbed
>Laguna for Gertsley. This glaze was mixed about two weeks ago. I fired
>anyway and the crystals did show up as little brown runny spots. So far it
>seems that Laguna's does alter certain glazes now if someone can tell us
>why?
>Thanks
>Richard
>
>The Kings wrote:
>
>> I send this call for help with some trepidation. I am a fledgling
>>potter dipping into glazes. I have limited with background in
>>glazemaking workshops. My technical background is limited. Currently I
>>am working with lowfire 04 terracotta clay. I am asking for help from
>>experienced potters. Here is my problem: I discovered about .5 cm
>>hexagonal crystals in my 100 g test glaze batches after sitting for about
>>a month. I called my supplier about this problem. Basicly they thought
>>it was funny. Said they never heard about that happening before.
>>Needless to say that doesn't help. The only difference that I noticed in
>>my recipe is that it calls for Gerstley Borate and I replaced it with
>>Lagunua Borate since I have discovered I can no longer get it. Now, I
>>have made other batches in the past with some Gerstley that I had on
>>hand. I did not have the crystal problem. Thus, does it have something
>>to do with the new borate? Most importanly, what do I do? The following
>>is the Satin Matt Glaze 04 that I am having trouble with:
>> Gerstley Borate 38g
>> Lithium carbonate 10
>> Nepheline Syenite 5
>> EPK Kaolin 5
>> flint 42
>> plus bentonite 1%
>> color variations (I use mason stains 3-6%)
>>
>> I do have a second question. I noticed that my matt has more shine
>>using the new borate. I'm not complaining. I don't know enough to do
>>that. I just want to know what to do.
>> This is my matt recipe
>> NCMatt 04
>> EPK Kaolin 16
>> Frit 3124 32
>> Gerstley Borate 32
>> Dolmite 20
>> I use oxides and carbonates to color this.
>> Oh yes, I have not noticed the crystal problem in the Matt glaze.
>> Thank you ahead of time to anyone that can be of help.
>> Confused but hopeful,
>> Kathleen King
>>
>>
>>__________________________________________________________________________
>>____
>> Send postings to clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list or change your subscription
>> settings from http://www.ceramics.org/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>>melpots@pclink.com.
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Edouard Bastarache on tue 13 mar 01
Allo Cindi,
here is Michael's excellent explanation of this phenomenon
Later,
Edouard Bastarache
Irr=E9ductible Qu=E9becois
Sorel-Tracy
Dans / In "La Belle Province"
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
"Any glaze containing both lithium carbonate and gerstley borate can
precipitate lithium borate crystals due to aqueous solute ion exchange
reactions. Lithium carbonate and colemanite (calcium borate) - in the
gerstley borate, exchange partners to form calcium carbonate and lithium
borate.
The soluble calcium is rapidly taken out of solution via this reaction as
calcium carbonate (calcite) has low solubility. Because the calcite is s=
o
insoluble (being removed as quickly as it is formed) the reaction continu=
es
as long as there is a source of soluble colemanite. The solution meanwhi=
le
becomes saturated in the other product, lithium borate which is more
soluble. Slow evaporation, or fluctuations in temperature cause coarse
lithium borate crystals to grow in the bucket. The calcite precipitates t=
oo
rapidly to form large crystals and likely will form a fine-grained scale =
on
the bucket walls and base, similar to the calcite scale on shower walls i=
n
hard-water regions.
Precipitation and removal of lithium borate crystals from glaze slop will
reduce boron and lithium (both potent fluxes) in the glaze, hence affecti=
ng
melting to some extent."
Michael Banks,
Nelson,
NZ
Lawrence Ewing on wed 14 mar 01
Hi Kathleen,
Here are two alternatives for your glazes reconstructed using Matrix.
One of the problems we have replacing GB by calculation is not knowing what
the analysis is for the GB you used. To overcome this I use in your
original recipes the rationalized analysis for GB given by Tony Hansen at
www.GerstleyBorate.com
These recipes are near chemical matches for your originals. I do not know
how well Laguna Borate reproduces GB's physical properties however. Laguna
Borate has a higher Al2O3 content than GB which leaves little room for clay
in low temperature glaze substitutions.
Kind regards,
--------------------------------------------------
SATIN MATT 04 Alternative Cone 04
--------------------------------------------------
Formula Weight% Recipe
--------------------------------------------------
KNO 0.1106 3.29% Lithium Carbonate 10.88
CaO 0.4175 9.99% Laguna Borate 40.79
MgO 0.0644 1.11% Neph. Sye. P3332 3.53
Li2O 0.4076 5.20% Silica 43.44
Al2O3 0.1142 4.96% Whiting 1.36
B2O3 0.4456 13.23%
SiO2 2.4285 62.24%
K2O 0.0265 1.06%
Na2O 0.0841 2.22%
Al:Si 21.2665
Expan. 6.8093
ST 292.468
--------------------------------------------------
NCMATT 04 Alternative Cone 04
--------------------------------------------------
Formula Weight% Recipe
-------------------------------------------------
KNO 0.1268 5.23% EPK Kaolin 9.68
CaO 0.6454 22.71% Ferro 3124 34.41
MgO 0.2278 5.76% Laguna Borate 34.41
Al2O3 0.1891 12.08% Dolomite 21.51
B2O3 0.3986 17.40%
SiO2 0.9750 36.75%
TiO2 0.0009 0.07%
K2O 0.0150 0.88%
Na2O 0.1118 4.35%
Al:Si 5.1569
Expan.10.5966
ST 303.429
Lili Krakowski on wed 14 mar 01
I do not want to tread on the smallest crocus just sticking its nose up.
But: it may not be your ingredients but that the glaze got too cold! We
had that discussion last year and the eyar before and before I think. I
forgot what it is--scientific folk rsvp--when something --is it
soda?--turns to crystals on top of the glaze bucket...reheating (stick
bucket behind stove for the night--takes care of things.
On
Tue, 13 Mar 2001, Mark Duerr wrote:
> Just a thought. Perhaps the Laguna is mined near
> a salt deposit. Take the crystals out and examine
> them. Also see if the crystals disappear if the
> solution is heated.
>
> A couple of weeks ago someone wrote about a problem
> they were having with GB. My first thought was,
> send it all to me, that will solve my problem. . .
>
> cheers,
>
> mark duerr
>
>
>
> >I too am getting crystals in a glaze that formerly did not! I also subbed
> >Laguna for Gertsley. This glaze was mixed about two weeks ago. I fired
> >anyway and the crystals did show up as little brown runny spots. So far it
> >seems that Laguna's does alter certain glazes now if someone can tell us
> >why?
> >Thanks
> >Richard
> >
> >The Kings wrote:
> >
> >> I send this call for help with some trepidation. I am a fledgling
> >>potter dipping into glazes. I have limited with background in
> >>glazemaking workshops. My technical background is limited. Currently I
> >>am working with lowfire 04 terracotta clay. I am asking for help from
> >>experienced potters. Here is my problem: I discovered about .5 cm
> >>hexagonal crystals in my 100 g test glaze batches after sitting for about
> >>a month. I called my supplier about this problem. Basicly they thought
> >>it was funny. Said they never heard about that happening before.
> >>Needless to say that doesn't help. The only difference that I noticed in
> >>my recipe is that it calls for Gerstley Borate and I replaced it with
> >>Lagunua Borate since I have discovered I can no longer get it. Now, I
> >>have made other batches in the past with some Gerstley that I had on
> >>hand. I did not have the crystal problem. Thus, does it have something
> >>to do with the new borate? Most importanly, what do I do? The following
> >>is the Satin Matt Glaze 04 that I am having trouble with:
> >> Gerstley Borate 38g
> >> Lithium carbonate 10
> >> Nepheline Syenite 5
> >> EPK Kaolin 5
> >> flint 42
> >> plus bentonite 1%
> >> color variations (I use mason stains 3-6%)
> >>
> >> I do have a second question. I noticed that my matt has more shine
> >>using the new borate. I'm not complaining. I don't know enough to do
> >>that. I just want to know what to do.
> >> This is my matt recipe
> >> NCMatt 04
> >> EPK Kaolin 16
> >> Frit 3124 32
> >> Gerstley Borate 32
> >> Dolmite 20
> >> I use oxides and carbonates to color this.
> >> Oh yes, I have not noticed the crystal problem in the Matt glaze.
> >> Thank you ahead of time to anyone that can be of help.
> >> Confused but hopeful,
> >> Kathleen King
> >>
> >>
> >>__________________________________________________________________________
> >>____
> >> Send postings to clayart@lsv.ceramics.org
> >>
> >> You may look at the archives for the list or change your subscription
> >> settings from http://www.ceramics.org/clayart/
> >>
> >> Moderator of the list is Mel Jacobson who may be reached at
> >>melpots@pclink.com.
> >
> >______________________________________________________________________________
> >Send postings to clayart@lsv.ceramics.org
> >
> >You may look at the archives for the list or change your subscription
> >settings from http://www.ceramics.org/clayart/
> >
> >Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
Lili Krakowski
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