Ivor and Olive Lewis on tue 18 sep 07
Dear Eric Suchman,
I am wondering why you would need to add Titanium dioxide ?
Substituting Nepheline Syenite for Potash felspar is an interesting =
proposition as a way of decreasing the maturity temperature of this =
glaze.
A month ago I would have said "yes" to our question and thoroughly =
recommended you test this idea. I still recommend the test but would be =
unsurprised if it did not work.
From independent sources I have found out that the thermal behaviour of =
Potash felspar is unusual. Samples with a formula K2O-Al2O3-6SiO2 do not =
melt at the temperature given in our noteworthy text books that are =
recommended as providing reliable knowledge.
The ramifications of this knowledge are profound and I am still sorting =
the ideas out.
If you do have a go I would be interested in your results and the =
analyses of the materials you use, if you do comparative tests. Might =
even try it out in my next firing.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ron Roy on wed 19 sep 07
Hi Ivor,
Adding some Rutile or TiO2 is usually a good idea - to help the
recrystallizing process. Don't usually need as much as 5% though.
Gives the forming crystals a place to start so the process goes faster.
RR
>Dear Eric Suchman,
>I am wondering why you would need to add Titanium dioxide ?
>Substituting Nepheline Syenite for Potash felspar is an interesting
>proposition as a way of decreasing the maturity temperature of this glaze.
>A month ago I would have said "yes" to our question and thoroughly
>recommended you test this idea. I still recommend the test but would be
>unsurprised if it did not work.
>From independent sources I have found out that the thermal behaviour of
>Potash felspar is unusual. Samples with a formula K2O-Al2O3-6SiO2 do not
>melt at the temperature given in our noteworthy text books that are
>recommended as providing reliable knowledge.
>The ramifications of this knowledge are profound and I am still sorting
>the ideas out.
>If you do have a go I would be interested in your results and the analyses
>of the materials you use, if you do comparative tests. Might even try it
>out in my next firing.
>Best regards,
>Ivor Lewis.
>Redhill,
>South Australia.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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