michael wendt on thu 29 mar 01
Help!
I have read repeatedly that Nepheline Syenite causes deflocculation of =
throwing bodies. Can anyone give me definitive research to back this up. =
I have used high levels of Nepheline Syenite in my throwing body for 27 =
years without noticing deflocculation at all. When I contacted Unimin =
Corporation and asked them, all their test data shows that Feldspars and =
Nepheline Syenite have nearly identical solubility in water. I quote =
Clay Collins of Unimin Corp.
"the difference between the levels of soluble Na ions in the two =
slips is quite small (-60 parts per million), and our tests show no =
measurable effect on the behavior."
Anecdotal evidence should be rejected and certainly never repeated, =
so my saying that I have seen no effect is the same as some one else =
saying they have. These people have accurately measured the effect using =
scientific methods and instruments which help to quantify the results. I =
would like to see the opposing data supporting the deflocculating effect =
in throwing bodies and examine the methods used.
Contact Clay Collins at clay.collins@unimin.com if you want the same =
data he gave me. Decide for yourself.
Thanks,
Michael Wendt wendtpot@lewiston.com
Craig Martell on fri 30 mar 01
At 08:24 AM 3/29/01 -0800, you wrote:
>Help!
>I have read repeatedly that Nepheline Syenite causes deflocculation of
>throwing bodies. Can anyone give me definitive research to back this up. I
>have used high levels of Nepheline Syenite in my throwing body for 27
>years without noticing deflocculation at all.
Hi Michael:
When my wife stopped making pots and started fusing glass I had to make a
mold claybody for her. It's fluxed with about 25% nepheline syenite. I
haven't seen any problems with deflocc and it's been mixed for quite some time.
regards, Craig Martell in Oregon
Ron Roy on thu 12 apr 01
Hi Michael,
Many years ago - when I had a clay mixing business we were using Buck Spar
to flux our bodies. The mine closed - we switched to Neph Sy (270) - we had
to eat a lot of deflocced clay.
It was simple - we took out the BuckSpar and replaced it with Neph Sy -
then the fun started.
We do use Neph Sy in some bodies - particularly cone 6 porcelaneous white
bodies - god help you if you leave the Ephesian salts out.
Some glazes with Neph Sy in them hard pan badly - when I take it out they
don't.
No doubt there are other factors at work here. If you have enough plastic
clay and/or bentonite you can stop the settling but because Neph Sy has so
much alumina it's sometimes difficult to keep enough raw clay in the
bucket.
Then there are those that only bisque to 08 - they need their glazes thin
so hard panning is more likely.
Then there is the question of flocculators in the clay or water which can
help to counteract the problem - or the opposite.
Neph Sy has lots of sodium - and less silica than other spars - it would
seem to me a set up for deflocculation give the right circumstances.
I would be interested to see any tests say between Custer, G200, F4 and
Neph Sy as to which would leach the most sodium. All my money will be on
the Neph Sy. Just don't use distilled water.
I would start with a weak solution of vinegar for starters. Remember - old
clay gets acid - helps the flocculation - better for pulling handles and
throwing but the acid will breakdown the Neph Sy faster - so it becomes a
time thing.
RR
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
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