Alex Solla on mon 7 jul 03
Ron, et al,
Was talking with Craig Martell a while back about c/6 bodies and their tendency to flocculate over time. Is there any reason NOT to use Soda Spar instead of Neph Sy in a body? Particularly these tight whiteware / porcelain bodies? I also wonder how many manufacturers of clay bodies are adding Epsom salts to counteract the Neph Sy effect?
Ideas???
thanks,
Alexander Solla
Cold Springs Studio
4088 Cold Springs Road
Trumansburg, NY
Ron Roy wrote:
Hi William,
I just did a search on the web - Zemex lists the analysis of their products
- G200, NC4 - 200 (a soda spar) and EPK to list a few.
The NC4 - 200 is very close to Kona F4 and to C6 Spar although the Unimin
site does not list analysis - I am going by old analysis that I got from
Hamille and Gillespie - Web: http://www.hamgil.com
Min spar 200 is close as well but less KNaO.
The soda spars have less KNaO than the potash spars but have more CaO.
If it's soda you want may I suggest at least some Neph Sy - it's got more.
I use F4 because it's easy for me to get but I would not be averse to
putting in some Neph Sy. If you use a boron frit with no Al2O3 you will be
able to float it OK with ball and bentonite I think.
I would recommend trying at least one set with G200 - alkaline is alkaline
- and you get more with the G200 and Neph Sy.
RR
>I would like to ask one quick question. Which Soda
>spars do most of you use? Why? Any particular problems
>or advantages over another that leads you to a certain
>one?
>This is my homework for the next month and I will
>un-veil some things regarding this down the NOT SO
>DISTANT road/future. Ron can you give me some
>information as to which spar you would use to effect a
>copper/tin turquoise ^6 Ox of course.
>Theres little need in me supplying a recipe of sorts
>right now. I am just highly curious as to favored soda
>spars and looking for comparisons from various sources
>and their reasons of use. Sourcing is important to me
>and I find that for whatever unknown reason many of us
>will be using certain materials as a whole more so
>than others. Like G-200 potash spar which I stock
>plenty of.
>
>William Edwards
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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Craig Martell on tue 8 jul 03
Hello Alex:
I've used a commercially prepared cone 10 porcelain that was fluxed with
soda spar. I know the guy who developed the clay and he told me what was
in it. I still have some of the clay and it's about 3 years old
now. Still has the same working properties.
They added some epsom salt to the mix but not because of the sodium ion
problem that you get with Neph sy. This particular body contains mostly
grolleg kaolin. When grolleg is mined by water jet, the clay is
deflocculated so it will flow better and aid gathering and
processing. Sound logic from their end but not real conducive to good
throwing. So the company that prepared the clay added some epsom salt to
counteract the deflocculant added for mining. On and on it goes!
My feeling about soda spar at cone 6 for clays is that it's a lot better
than potash feldspar with regard to fusion. If a comparison is made
between potash feldspar fusions at cone 10 and soda spar fusions at cone 6,
they are pretty close. Potash spar fusions at cone 6 aren't all that
great. Soda spars give very good color response in whitwares too. Glazes
are a bit more vivid if you like that sort of thing.
regards, Craig Martell Hopewell, Oregon
Ron Roy on wed 9 jul 03
I don't like soda spars - you get less KNaO per pound for one thing. I
would use a potash spar - I recommend G200 if you are in North America. Get
the most reliable one with the most KNaO.
If you go from Neph Sy to soda spar you have to add a lot more - simply
does not react like Neph Sy.
Neph Sy is OK for 6 you just have to add some epson salts to counter the
defloccing of the soluble soda.
I like the combination of Neph Sy and pot spar - allows easy absorbency
adjustments.
Use 2 lb. Epson salts to 1000 lb. dry mix - make sure the salts are
completely disolved befor adding into mixing water.
The two companies I work for add Epson salts to all bodies with Neph Sy -
the clay is unworkable soon after mixing if it's not added.
The reason pot spars are recommended for high fire clays is becuase sodium
oxide voilitzes above cone 6 and tends to salt the inside of kilns and
shelves. Not a big thing but it's why pot spars are better.
Body fluxing at 6 is OK with some CaO or MgO but as you get up higher it's
not a good idea because they don't work to avoid cristobalite. Got to be
sure you have enough KNaO is the trick.
RR
>Was talking with Craig Martell a while back about c/6 bodies and their
>tendency to flocculate over time. Is there any reason NOT to use Soda Spar
>instead of Neph Sy in a body? Particularly these tight whiteware /
>porcelain bodies? I also wonder how many manufacturers of clay bodies are
>adding Epsom salts to counteract the Neph Sy effect?
>
>Ideas???
>
>thanks,
>Alexander Solla
>
>Cold Springs Studio
>4088 Cold Springs Road
>Trumansburg, NY
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
David Beumee on wed 9 jul 03
Very interesting comment about deflocculation of Grolleg.
I wonder if Standard Porcelain and Super Standard are
also deflocculated. I have noticed some increased
plasticity with Standard in comparison to Grolleg. Also,
since the kaolins are washed from the cliffs, the clays
are filter pressed, dried out, crushed, and presumably
screened before bagging. I've always wondered if
calcining ocurrs in the heating process, rendering
the kaolin non plastic, and I wonder about the
plasticity of Grolleg or Standard Porcelain as a filter
pressed cake, before the clay has the water driven
off by heat. I'll bet the plasticity is wonderful.
David Beumee
Earth Alchemy Pottery
Lafayette, CO
7/8/03 10:39:10 AM, Craig Martell wrote:
>Hello Alex:
>
>I've used a commercially prepared cone 10 porcelain that was fluxed with
>soda spar. I know the guy who developed the clay and he told me what was
>in it. I still have some of the clay and it's about 3 years old
>now. Still has the same working properties.
>
>They added some epsom salt to the mix but not because of the sodium ion
>problem that you get with Neph sy. This particular body contains mostly
>grolleg kaolin. When grolleg is mined by water jet, the clay is
>deflocculated so it will flow better and aid gathering and
>processing. Sound logic from their end but not real conducive to good
>throwing. So the company that prepared the clay added some epsom salt to
>counteract the deflocculant added for mining. On and on it goes!
>
>My feeling about soda spar at cone 6 for clays is that it's a lot better
>than potash feldspar with regard to fusion. If a comparison is made
>between potash feldspar fusions at cone 10 and soda spar fusions at cone 6,
>they are pretty close. Potash spar fusions at cone 6 aren't all that
>great. Soda spars give very good color response in whitwares too. Glazes
>are a bit more vivid if you like that sort of thing.
>
>regards, Craig Martell Hopewell, Oregon
>
>______________________________________________________________________________
>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.
>
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