Jim Tabor on tue 4 feb 03
I don't know the temp you fire but my experience at ^1 is a shorter
range of maturity. Neph sy appears to melt more quickly and could cause
problems with your body slumping if slightly too hot or soaked for a
period at peak. Industrial bodies use it but temp control is maintained
to a high degree. Consider using feldspar.
If you are set on using NS, the A400 has a smaller range of particles
with greater surface area and dissolves in the melt quicker while the
A270 has more large particles that would have an advantage for a body.
The choice may be best determined by how the clay is to be formed. Slip
casting may be better off with the A400 to help suspension but for
forming with plastic clays, I prefer a good range of particle size. At
school are the tech sheets with info on neph sy from the manufacture
that includes different bodies and their recommendations for using it.
Try bars with neph and bars with feldspar that have increased amounts of
each and see if the results fit your needs. Also, small pots with your
glazes applied to the sample bodies will indicate how well they fit. I
prefer to settle on a claybody and fit glazes to it, however, a little
extra test batch to include glaze testing can help settle issues more
quickly.
It will be interesting to hear from others using NS for their body. I
believe the maturity range of a claybody should span at least 2 cones
but that didn't happen from my experience with NS. With 2 cones
difference it was slightly underfired or slightly overfired. I also made
some changes to the clays I use and have a body with the temp span that
is trouble free.
If you want to contact me off list for the tech sheet info, I will pass
on the source.
Jim Tabor
Kat Valenzuela wrote:
> Hello:
> I am formulating a clay body and was wondering
> if anybody had advice on which Nepheline Syenite
> size would be best. A270 or A400?
>
> Any Clay expert advice would be great!
>
> Kat
> mudkat@monarch.net
> kat@digitalfire.com
>
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Kat Valenzuela on tue 4 feb 03
Hello:
I am formulating a clay body and was wondering
if anybody had advice on which Nepheline Syenite
size would be best. A270 or A400?
Any Clay expert advice would be great!
Kat
mudkat@monarch.net
kat@digitalfire.com
Ron Roy on wed 5 feb 03
Hi Kat,
Use the 270 - the finer grind is going to deflocc the body faster - better
add some Epsom salts - the body will deflocc even with the 270 - just a
matter of time.
Use 2 lb. per 1000 lb. dry weight of body mix
Thats 0.2 lb. per 100 dry - about 90 grams.
Make sure the salts are well dissolved in very hot water - sieve out any
undissolved crystals if you are fussy - add to the dry mix after dry mixing
- with the water.
When the Buck spar mine closed down we tried making bodies with Neph Sy -
they all deflocced - bad news all around.
RR
>Hello:
>I am formulating a clay body and was wondering
>if anybody had advice on which Nepheline Syenite
>size would be best. A270 or A400?
>
>Any Clay expert advice would be great!
>
>Kat
>mudkat@monarch.net
>kat@digitalfire.com
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
iandol on thu 6 feb 03
Dear Jim Tabor <>
You say <with your body slumping if slightly too hot or soaked for a period at =
peak. >>
This may be one of those rare cases where there is a Mineral Eutectic =
present, such as might be recorded in a Phase Equilibrium Diagram. =
Refer to "Phase Diagrams for Ceramists" Acers publication. Fig 786 and =
let me know what you think.
Best regards,
Ivor Lewis. Redhill, South Australia.
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