Tom Buck on fri 23 feb 07
Rutile is crude Titanium-4 Oxide, TiO2, 93% by weight,
contaminated with Iron Oxide, possibly FeO, probably Fe2O3, or a mix of
both, and some zirconium oxide, ZrO2, and a bit of kaolin, Al2O3.SiO2.
as such, it behaves like pure TiO2, and will serve as a colourant
much like a stain or an opacifiying agent like Zircon (zirconium silicate,
aka Ultrox, Zircopax), or Tin Oxide.
Since TiO2 melts at 1640 oC (2980 oF), when included at high
amounts in an alumino-silica glaze recipe, the rutile is most unlikely to
join silica, SiO2, in the forming of glass that the recipe is supposed to
make. Instead it will be dispersed in the molten Al2O3.SiO2 glass, and
cause the cooled glaze to be opaque, and perhaps coloured.
If you use pure TiO2 (made as a pigment for paint, enamels, and
tiles), you will have different colour responses from varying amounts of
TiO2 according to the make-up of the glaze itself. see books by Parmelee,
Hamer&Hamer, and Rhodes for some details on the behaviour of TiO2 at
various amounts, etc.
til later. peace Tom B.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada