Mert & Holly Kilpatrick on fri 23 nov 01
I used up our supply of spodumene in the middle of mixing up a glaze and
opened a new bag and the two materials look totally different - the old
supply was grey and very fine and dense. The material in the new bag is
white, with a high proportion of shiny particles - mica? quartz? When I
look in the supplier's catalog it says "Spodumene, chemical" although it
doesn't say that on the bag. I had gotten the old bag four or five years
ago from a different supplier. I will test the batch before glazing things
I care about, but can anyone explain this to me? Could they both be
spodumene?
Since I learned recently from Pete Pinnell's post that strontium shouldn't
have small boulders in it, I am less inclined to just say, "It must be ok."
Thanks,
Holly
Tony Ferguson on fri 23 nov 01
I have noticed spodumene tends to turn grey with age. If it is from a
different supplier, test. You could as for a chem work up on the spod from
both suppliers.
Tony
----- Original Message -----
From: "Mert & Holly Kilpatrick"
To:
Sent: Friday, November 23, 2001 6:00 AM
Subject: Spodumene Question
> I used up our supply of spodumene in the middle of mixing up a glaze and
> opened a new bag and the two materials look totally different - the old
> supply was grey and very fine and dense. The material in the new bag is
> white, with a high proportion of shiny particles - mica? quartz? When I
> look in the supplier's catalog it says "Spodumene, chemical" although it
> doesn't say that on the bag. I had gotten the old bag four or five years
> ago from a different supplier. I will test the batch before glazing
things
> I care about, but can anyone explain this to me? Could they both be
> spodumene?
>
> Since I learned recently from Pete Pinnell's post that strontium shouldn't
> have small boulders in it, I am less inclined to just say, "It must be
ok."
>
> Thanks,
> Holly
>
>
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Hank Murrow on sat 24 nov 01
Holly wrote;
>I used up our supply of spodumene in the middle of mixing up a glaze and
>opened a new bag and the two materials look totally different - the old
>supply was grey and very fine and dense. The material in the new bag is
>white, with a high proportion of shiny particles - mica? quartz? When I
>look in the supplier's catalog it says "Spodumene, chemical" although it
>doesn't say that on the bag. I had gotten the old bag four or five years
>ago from a different supplier. I will test the batch before glazing things
>I care about, but can anyone explain this to me? Could they both be
>spodumene?
Dear Holly;
At one time, I had seven different kinds of Spodumene in my studio,
going back 30 years. I finally, at Jim Robinson's suggestion, made fusion
buttons (pack dry material in thimble and turn over on piece of bisque) of
these materials and fired them to my operating temperature (C/10R) and
looked at the results. About half were completely melted and tended to
slump down and were a brown color. The other half remained pinkish and
remained someshat sugary. Yet another was whitish, but melted the most. I
put all the dark ones together in a large fiber drum and hotglued a fusion
button to a card that said, "Dirty Spodumene". The others I put in a barrel
that said. "clean Spodumene". The remaining sample I put in a bucket that
said, "Low Melt Spodumene". When I want a darkish shino I use the dirty
one, and so on. This is something I did also for my many samples of
lepidolite and bone ash. The fusion button really does "reveal all".
Hope this helps, Hank in Eugene
Rod & Erin on sun 25 nov 01
That old supply of spod was from a bad batch going around a couple years
ago.. You must have had it for awhile.. Spod is supposed to be nice and
white ;)
Rod
RedIron Studios
Vancouver, B.C
----- Original Message -----
From: "Mert & Holly Kilpatrick"
To:
Sent: Friday, November 23, 2001 6:00 AM
Subject: Spodumene Question
> I used up our supply of spodumene in the middle of mixing up a glaze and
> opened a new bag and the two materials look totally different - the old
> supply was grey and very fine and dense. The material in the new bag is
> white, with a high proportion of shiny particles - mica? quartz? When I
> look in the supplier's catalog it says "Spodumene, chemical" although it
> doesn't say that on the bag. I had gotten the old bag four or five years
> ago from a different supplier. I will test the batch before glazing
things
> I care about, but can anyone explain this to me? Could they both be
> spodumene?
>
> Since I learned recently from Pete Pinnell's post that strontium shouldn't
> have small boulders in it, I am less inclined to just say, "It must be
ok."
>
> Thanks,
> Holly
>
>
____________________________________________________________________________
__
> 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.
Hank Murrow on sun 25 nov 01
>> I used up our supply of spodumene in the middle of mixing up a glaze and
>> opened a new bag and the two materials look totally different - the old
>> supply was grey and very fine and dense. The material in the new bag is
>> white, with a high proportion of shiny particles - mica? quartz? When I
>> look in the supplier's catalog it says "Spodumene, chemical" although it
>> doesn't say that on the bag. I had gotten the old bag four or five years
>> ago from a different supplier. I will test the batch before glazing
>things
>> I care about, but can anyone explain this to me? Could they both be
>> spodumene?
>> Thanks,
>> Holly
>That old supply of spod was from a bad batch going around a couple years
>ago.. You must have had it for awhile.. Spod is supposed to be nice and
>white ;)
>
>Rod
>RedIron Studios
Well, sure..........just send the bag on to me for proper 'disposal'!
Hoping, Hank in Eugene
Tony Ferguson on wed 31 jul 02
Les,
I forgot to mention--I actually do reduce at the end of the firing. I
forgot about that. What kind of kiln are you firing?
Tony
----- Original Message -----
From: "Les Crimp"
To:
Sent: Wednesday, July 31, 2002 4:19 PM
Subject: Re: Spodumene question
> Tony (Ferguson) -
>
> I have a wood-fired kiln and I put it into reduction for 60 minutes when
it
> reaches 800C. I also reduce for about 20 minutes before the last stokes
> before shutting it down. Works well.
>
> Les Crimp on that Island in the Pacific.
> lcrimp@shaw.ca
>
>
____________________________________________________________________________
__
> 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.
>
Marni Turkel on wed 31 jul 02
Roger,
Be careful making the assumption that one kind of spodumene is the
same as another. I have had more than noticeable differences (read
that as disaster) when the source changed. You might be fine, but I
would definitely test it first--maybe mix a small batch of the glaze
using only the new spodumene and see if the results are different.
You could be fine, but maybe not.
Good luck.
Marni
>I ran out of spodumene formulating a glaze. Got another bag of it and it
>seems to be of a finer mesh. ... My guess is that this will
>not make a difference once they have both been immersed in H20. Is this a
correct assumption based on anyone's past experience?
--
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
MOORE, Robert J. on wed 31 jul 02
I ran out of spodumene formulating a glaze. Got another bag of it and it
seems to be of a finer mesh. The initial batch had crystal-like particles
and one could see the light bouncing off of them. Not so on the second
batch, it look similar to flour no glimmering. My guess is that this will
not make a difference once they have both been immersed in H20. Is this a
correct assumption based on anyone's past experience? I looked the Hammer
book and it did not indicate info. on this.
The firing it will be in is: wood, cone 10-11, on bisque
Another question related to a wood firing I have meant to ask on here. In my
past experience I have been told to reduce for the clay body around cone 08.
Is it necessary to do this in a wood firing where the ox., reduction
atmosphere changes constantly?
Input will be greatly appreciated.
Robert J. Moore
in Southern Indiana
Tony Ferguson on wed 31 jul 02
Robert,
You do not have to "reduce" when you are wood firing. Reduction and
Oxidation are part of the natural cycle in a good stoking pattern. When you
stoke, you are reducing--at the end of the burn you are oxidizing and so
forth. If you consistently have too much black smoke, you are stoking too
regulary and over-reducing. Stoking patterns depend on many things such as
size of kiln, method of packing, kind of wood, moisture, pressure, etc. I
have found the key to each firing is finding a good rhythm to your stoking
and not deviating from it. Have fun.
Thank you.
Tony Ferguson
Stoneware, Porcelain, Raku
www.aquariusartgallery.com
218-727-6339
315 N. Lake Ave
Apt 312
Duluth, MN 55806
----- Original Message -----
From: "MOORE, Robert J."
To:
Sent: Wednesday, July 31, 2002 5:04 AM
Subject: Spodumene question
> I ran out of spodumene formulating a glaze. Got another bag of it and it
> seems to be of a finer mesh. The initial batch had crystal-like particles
> and one could see the light bouncing off of them. Not so on the second
> batch, it look similar to flour no glimmering. My guess is that this will
> not make a difference once they have both been immersed in H20. Is this a
> correct assumption based on anyone's past experience? I looked the Hammer
> book and it did not indicate info. on this.
> The firing it will be in is: wood, cone 10-11, on bisque
>
> Another question related to a wood firing I have meant to ask on here. In
my
> past experience I have been told to reduce for the clay body around cone
08.
> Is it necessary to do this in a wood firing where the ox., reduction
> atmosphere changes constantly?
>
> Input will be greatly appreciated.
>
> Robert J. Moore
> in Southern Indiana
>
>
____________________________________________________________________________
__
> 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.
>
Les Crimp on wed 31 jul 02
Tony (Ferguson) -
I have a wood-fired kiln and I put it into reduction for 60 minutes when it
reaches 800C. I also reduce for about 20 minutes before the last stokes
before shutting it down. Works well.
Les Crimp on that Island in the Pacific.
lcrimp@shaw.ca
Les Crimp on thu 1 aug 02
Tony -
My kiln is a 30 cu.ft. downdraft stoked with a Bourry box. Very efficient.
It was built for me by Graham Sheehan who lives on Gabriola Island here in
B.C.
Best regards,
Les.
lcrimp@shaw.ca
Ron Roy on sat 3 aug 02
Hi Robert,
What we need to know is what kind you had before and what kind the new
kind is. I may have the analysis for both - then it's just a matter of
calculating the difference and making adjustments to the glaze batch.
RR
>I ran out of spodumene formulating a glaze. Got another bag of it and it
>seems to be of a finer mesh. The initial batch had crystal-like particles
>and one could see the light bouncing off of them. Not so on the second
>batch, it look similar to flour no glimmering. My guess is that this will
>not make a difference once they have both been immersed in H20. Is this a
>correct assumption based on anyone's past experience? I looked the Hammer
>book and it did not indicate info. on this.
>The firing it will be in is: wood, cone 10-11, on bisque
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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