Undetermined origin c/o LISTSERV administrator on wed 28 jan 04
Dear Joanne,
Soapstone, as you have been told is Talc, a magnesian silicate mineral. =
It is used as a body flux in some clay preparations and I like to use it =
with Wollastonite in glazes because of the way it helps to produce =
translucent silky surfaces.
Granite is a Rock, a mixture which will generally contain some form of =
Felspar, free silica as Quartz, one or more forms of Mica, often some =
free Iron Oxide such as Magnetite or Haematite and perhaps some =
accessory minerals such as Rutile. So, of itself it will make a fine =
glaze with a green hue, usually above cone 8.
The best source for all rock powder is at the quarry crusher around =
which you might find deep drifts of ultrafine powder that needs no more =
than screening through a #*80 screen.
Beware of the residues from processed Granite. The slurry from grinders =
will cause problems unless the abrasives used were Diamond. Avoid using =
powder which has been contaminated with Silicon Carbide during grinding =
or polishing, except where you would like to get a local reduction, =
though I have fond this to be a violent reaction.
Enjoy your experimentation,
Ivor Lewis. Redhill, South Australia
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