Terri Storer on tue 18 nov 97
Hi Clayarters!
I have been lurking for quite some time now, and have really enjoyed the
list. I'm hoping someone can help with an annoying problem I
encountered recently. I have been storing my glazes in my garage where
it has been cool but not freezing. Last week when I was glazing, I
noticed 6 sided, flat, clear, crystal like things in the bottom of my
glaze bucket. They ranged in size from very small (salt grain sized) to
about 5/8 '' across. I seived them out, and ground them up with a
mortar and pestal, and put them back into the glaze. I then proceeded
to glaze my pots and fired them in a normal fashion. The glaze came out
fine. How can I avoid this problem in the future?
The glaze recipe is:
Tenmoku Gold cone 6 oxidation
Cornish stone 61
whiting 8
gerstley borate 3
lithium carb 5.5
dolomite 7
flint 5.5
Red iron oxide 10
Any help will be greatly appreciated!
Terri Storer in Colorado
Don Prey on wed 19 nov 97
Terri,
I think you are growing sodium silicate crystals. I am not aware of any way
to prevent this except to keep the glaze in a warmer storage area.
Don Prey
Louis Katz on thu 20 nov 97
------------------
=3E Tenmoku Gold cone 6 oxidation
=3E Cornish stone 61
=3E whiting 8
=3E gerstley borate 3
=3E lithium carb 5.5
=3E dolomite 7
=3E flint 5.5
=3E Red iron oxide 10
The simple solution is to keep your glazes out of solution by using
insoluble materials. Gertsley Borate and Lithium Carbonate have enough
solubility to cause problems.
Materials go into solution and as the temperature drops come out of
solution. Often the materials that come out are in different
combinations than when they went in. Because materials prefer to
crystalize on a seed the new materials can appear in large sizes.
Here is my attempt at removing all the soluble materials. It is so
different from the original that I suspect it won't look the same, but
the Unity formula is close. I have no idea how durable it might be.
Also it is very low in clay. If you test this I would love to know how
it works.
Louis
Cone: 6
Recipe: Percent
Bentonite 1.73
Ferro Frit 3134 3.77
Spodumene 32.91
Ferro Frit 3110 21.22
Dolomite 7.28
Whiting 8.05
Flint 14.91
Red Iron Oxide 10.13
Totals: 100.00 =25
Unity Formula for testcone6Tenmoku:
0.026 K2O=CA 0.276 Al2O3 2.567 SiO2=CA
0.177 Na2O 0.061 B2O3=CA 9.3:1 Si:Al Ratio
0.465 CaO=CA 0.180 Fe2O3
0.119 MgO=CA 0.003 P2O5=CA
0.212 Li2O
Percentage Analysis:
57.90 =25 SiO2
10.55 =25 Al2O3
1.58 =25 B2O3
0.90 =25 K2O
4.13 =25 Na2O
9.80 =25 CaO
1.80 =25 MgO
2.37 =25 Li2O
10.78 =25 Fe2O3
0.15 =25 P2O5
LINDA BLOSSOM on thu 20 nov 97
Hi Terri,
You will probably notice the problem with crystals more in the winter - I
have heated a glaze to get the crystals to go back into solution. Have you
tried this glaze without the lithium carb? I have a glaze that does this
and it looks the same without the small percent of LiCO3.
Linda Blossom
2366 Slaterville Rd.
Ithaca, NY 14850
607-539-7912
blossom@lightlink.com
http://www.artscape.com
George Mackie on fri 21 nov 97
Linda/ Terri- I have a couple of glazes which produce flat hexagonal
crystals. They both contain gerstley borate as well as lithium carbonate.
My glazes which have either but not both these fluxes do not produce
crystals. The books tell you to add epsom salts to the glaze mix to
prevent crystals but it doesnt always work. You can seive out the
crystals, melt them in hot water and put back into the glaze or do as
Linda suggests and heat up the whole glaze. Leaving the Lithium out may
work too but this could result in crazing as the lithium may be there to
counteract the high shrinkage of other alkaline components. George
On Thu, 20 Nov 1997, LINDA BLOSSOM wrote:
> ----------------------------Original message----------------------------
> Hi Terri,
>
> You will probably notice the problem with crystals more in the winter - I
> have heated a glaze to get the crystals to go back into solution. Have you
> tried this glaze without the lithium carb? I have a glaze that does this
> and it looks the same without the small percent of LiCO3.
>
>
> Linda Blossom
> 2366 Slaterville Rd.
> Ithaca, NY 14850
> 607-539-7912
> blossom@lightlink.com
> http://www.artscape.com
>
Jean Lehman on sat 22 nov 97
This glaze will also develop crystals, especially in cold weather.
It also goes through a really stinky phase.
Note that it doesn't have either gerstley borate or lithium in it...
It is a really nice saturated iron glaze...
It is stable, doesn't do anything weird, except stink and deveop crystals.
I forget where I got it... it is not an original to me...
RUST (cone 9-10, ox)
Soda Feldspar (KONA) 25 2000
Flint 28 2240
EPK 20 1600
Whiting 10 800
Dolomite 10 800
Bone Ash 7 560
------ ------
100 8000
Red Iron Oxide 12 960
Bentonite 2 160
Jean
>----------------------------Original message----------------------------
>Linda/ Terri- I have a couple of glazes which produce flat hexagonal
>crystals. They both contain gerstley borate as well as lithium carbonate.
>My glazes which have either but not both these fluxes do not produce
>crystals. The books tell you to add epsom salts to the glaze mix to
>prevent crystals but it doesnt always work. You can seive out the
>crystals, melt them in hot water and put back into the glaze or do as
>Linda suggests and heat up the whole glaze. Leaving the Lithium out may
>work too but this could result in crazing as the lithium may be there to
>counteract the high shrinkage of other alkaline components. George
>
>On Thu, 20 Nov 1997, LINDA BLOSSOM wrote:
>
>> ----------------------------Original message----------------------------
>> Hi Terri,
>>
>> You will probably notice the problem with crystals more in the winter - I
>> have heated a glaze to get the crystals to go back into solution. Have you
>> tried this glaze without the lithium carb? I have a glaze that does this
>> and it looks the same without the small percent of LiCO3.
>>
>>
>> Linda Blossom
>> 2366 Slaterville Rd.
>> Ithaca, NY 14850
>> 607-539-7912
>> blossom@lightlink.com
>> http://www.artscape.com
>>
---------------------->
Jean Lehman, in Lancaster, PA
j_lehman@acad.FandM.EDU (that's an _underscore_ not a hyphen)
http://www.art-craftpa.com/lehman.html
Check out the 1997 Strictly Functional Pottery National at:
http://www.art-craftpa.com/art-craftpa.html
Linda Arbuckle on sun 23 nov 97
George commented:
> The books tell you to add epsom salts to the glaze mix to
> prevent crystals but it doesnt always work.
>
Epsom salts is a flocculant that changes the orientation of the
particles (they orient end to middle and form flocs). To do so it
exchanges ions and can actually cause calcium to precipitate, if I
understand Frank Hamer in A Potter's Dictionary (Flocculation). So I
don't know that I'd say that epsom salts prevents crystallization.
Interesting observation that Gerstley Borate or Lithium alone don't
seem to promote crystal growth in the bucket. As an aside, Lithium
Carbonate will deflocculate a glaze, which means it settles into a hard
mass in the bottom of the bucket.
Linda
Linda Arbuckle
Associate Professor, Graduate Coordinator
University of Florida, Box 115801, Gainesville, FL 32611-5801
e-mail:arbuck@ufl.edu (Note: this is a new e-mail address)
Cathie Feild on sun 23 nov 97
In a message dated 97-11-22 21:58:52 EST, you write:
<< This glaze will also develop crystals, especially in cold weather.
It also goes through a really stinky phase.
Note that it doesn't have either gerstley borate or lithium in it...
It is a really nice saturated iron glaze...
It is stable, doesn't do anything weird, except stink and deveop crystals.
I forget where I got it... it is not an original to me... >>
REPLY---------------------------------
I can't believe it! I guess you have to read all messages that come through
on Clayart or risk missing something that will end up being relevant to you.
I had been deleting without reading all the messages with the heading,
"crystals precipitating out of glaze," thinking they had to do with
crystaline glazes which I'm not interested in (at least at the moment).
Then, today, when I was stirring a glaze that had been sitting in our
unheated garage for several weeks since I last used it, I heard this funny
clink, clink sound. I thought maybe I had left the hydrometer in the bucket
by mistake and it had broken, but then I saw it safely on the shelf. I
fished around and came up with a handful of dime sized "things" that looked
like clear plastic or glass. We have a dog/house sitter who stays here when
we are gone over night and she sometimes brings a young child with her. My
husband and I were wondering if she somehow put something in the glaze bucket
when we weren't here and were getting pretty annoyed at the thought of it.
Then, I decided I better re-sieve the glaze if I was going to use it. In
pouring it through the sieve we discovered hundreds of tiny, six-sided clear
disks with little six point stars in the middle. I was fascinated and
baffled by this and was going to post a message to the list describing it
titled something like, "Tenmoku Gold--What's in this stuff?". So, tonight
when I saw the message with the "crystals" heading, a light-bulb went off in
my head and I read it. Lo and behold, this must be the same thing!
I had wondered if they would melt, like an ice cube, so set them out to dry
in a warm place. Well, they didn't melt, just kind of got dry and
"crispier" around the edges. Also, upon close examination, they look like
little sandwich cookies, with two "plates" with the star design sandwiched in
the middle. The bigger chunks look more like broken pieces of plastic, but
most of them also are six-sided, although not all, and they don't have the
star design, that I can see. I decided to go ahead and put this glaze on
some bowls (minus the crystals), since everything I do at this stage (novice)
is an experiment. I wonder if the glaze will come out looking the same as
before. I will find out when I unload the kiln tomorrow. By the way, this
glaze has Gerstly Borate, Lithium Carb, and 10 percent red iron oxide in it
(I posted formula several days ago under heading "Oxidation Tenmoku.") Sorry
this is so long, but I just got so excited when I read this post. . .now I
wish I'd read those other messages about "crystals precipitating out of
glaze." I guess I'll have to learn how to search the Clayart archives :-)
Cathie in Maryland
cfeild@aol.com
The Shelfords on mon 24 nov 97
Hi all -
Just re-set the listserv command to get back onto clayart, and I find a
discussion of my tenmoku gold making crystals. This is fascinating - it's
never done it to me. Different materials in different parts of the
country, or something? Has anybody just stirred and dipped, and fired a
lumpy glaze? It might turn out more varied in surface effect, or
something. Or of course, it might just turn out lumpy...
- Veronica
____________________________________________________________________________
Veronica Shelford
e-mail: shelford@island.net
s-mail: P.O. Box 6-15
Thetis Island, BC V0R 2Y0
Tel: (250) 246-1509
____________________________________________________________________________
Louis Katz on tue 25 nov 97
My one experience with this particular problem (glazes with crystals
precipitating out, where the glaze contains Lithium Carbonate and Gertsley
Borate) was just last spring. I seived a raku glaze and threw out scads
of crystals and decided to fire it anyways. Should have known by the color
that the firing was up around cone ten. Didn't know until I saw the color
of the foot of the pot.
Perhaps we are creating Lithium Metaborate or Lithium Tetraborate? Perhaps
one of the less ionically challenged can help us.
On a similar subject a student mixed a glaze calling for boric acid and
soda ash and ended up poping the lidoff her container from the escaping
carbon dioxide. Not all of our chemicals are inert.
Louis
Don Prey on wed 26 nov 97
Veronica,
For years I used a glaze I developed containing some lithium and gertsley.
The colorants were cobalt and copper resulting in a varigated blue at cone 6
in an electric kiln. Occasionally it would get cool enough in the basement
(and the glaze would sit unstirred long enough) to develop sodium silicate
crystals. On a few occasions, I just used it that way. Crystals stuck to
the pot and went into the kiln that way. It usually had a positive effect on
the variation in surface finish that I was looking for....If you get a chance
try it.
Don Prey in Oregon
shelford on thu 27 nov 97
Thanks for the note, Don. Sounds like an interesting effect. I guess up to
now, the tenmoku gold was only used at the Richmond Potters Club or in the
back bedroom I used as a studio - no place for it to get cold. Now my new
studio is in the garage, and is about to get thoroughly cold between uses,
so we'll see. I'm always one to try the simplest fix first - surprising how
often it's at least as good, or even an improvement on the original! Life
is short, and all that.
- Veronica
>----------------------------Original message----------------------------
>Veronica,
>For years I used a glaze I developed containing some lithium and gertsley.
> The colorants were cobalt and copper resulting in a varigated blue at cone 6
>in an electric kiln. Occasionally it would get cool enough in the basement
>(and the glaze would sit unstirred long enough) to develop sodium silicate
>crystals. On a few occasions, I just used it that way. Crystals stuck to
>the pot and went into the kiln that way. It usually had a positive effect on
>the variation in surface finish that I was looking for....If you get a chance
>try it.
>
>Don Prey in Oregon
>
>
___________________________________________
Veronica Shelford
e-mail: shelford@island.net
s-mail: P.O. Box 6-15
Thetis Island, BC V0R 2Y0
Tel: (250) 246-1509
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