Rutile is the mineral name for the naturally occurring crystals of titanium dioxide. While this material does produce creams, yellows, and oranges, it is not considered a colorant but a variegator in glazes. It can produce crystalline, speckling, streaking, and mottling effects in glazes during cooling.
Rutile can be purchased as lite rutile, which is a calcined powder, dark rutile, a raw powder, and granular. It is best to use Lite rutile in glazes for less imperfections during firing.
Information gathered from Digitalfire Ceramic Materials Database and The Potter's Dictionary of Materials and Techniques by Frank Hamer.
