Barb & Ray Sapergia on thu 5 jun 97
Hi,
I'm asking this on behalf of a friend who has a formula for clay which
has NC4 Feldspar listed as a major ingredient. Does anybody out there
know what this is and whether he can substitute Kona or Custer for it?
Thanks in advance,
Barb Springer-Sapergia in beautiful Chemainus, BC
- had summer last week, now back to winter :-(
Dave Eitel on fri 6 jun 97
>----------------------------Original message----------------------------
>Hi,
>I'm asking this on behalf of a friend who has a formula for clay which
>has NC4 Feldspar listed as a major ingredient. Does anybody out there
>know what this is and whether he can substitute Kona or Custer for it?
>
>Thanks in advance,
>Barb Springer-Sapergia in beautiful Chemainus, BC
>- had summer last week, now back to winter :-(
It's a soda spar, as is Kona. Custer is a potash spar. I've used nc4 as a
direct substitute for kona with no change in the glaze.
Later...Dave
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI
pots@cedarcreekpottery.com
http://www.cedarcreekpottery.com
Robert Kittel on fri 6 jun 97
At 08:08 PM 6/5/97 +0000, you wrote:
>----------------------------Original message----------------------------
>Hi,
>I'm asking this on behalf of a friend who has a formula for clay which
>has NC4 Feldspar listed as a major ingredient. Does anybody out there
>know what this is and whether he can substitute Kona or Custer for it?
NC4 is kona f4 only more refined, less iron impurities i imagine. If you
don't have NC4 use Kona f4.
Bob
Ron Roy on fri 6 jun 97
>----------------------------Original message----------------------------
>Hi,
>I'm asking this on behalf of a friend who has a formula for clay which
>has NC4 Feldspar listed as a major ingredient. Does anybody out there
>know what this is and whether he can substitute Kona or Custer for it?
Hi Barb,
As usual the answer is - it depends. How much feldspar (percent) and what
cone are they firing to.
Kona f4 and NC4 are quite similar - both are soda spars. If this clay is
being fired above cone 6 then the spar of choice would be a potash spar.
This is because sodium is volitile above cone 6 and a pot spar would be
easier on your kiln and furniture.
There is some difference howeven between the NC4 and Custer and if the
amount of spar is only 5% then I think it will be OK to sub equal amounts
of Custer for NC4 - otherwise send me the recipe and I will calculate to
make sure everything will be OK.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/ronroy.htm
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