Rutile is believed to collect in the lungs and cause deposits of black pigmentation, which leads to potentially serious restrictive lung impairment and pneumoconiosis, both of which can be fatal. Reduced exposure and comparatively less harmful results of inhalation may be ‘metal fume fever’, irritation of the respiratory tract and chronic bronchitis. It has a carcinogenic rating of 2B, meaning that it has been known to cause cancer in animals but the affect on humans is currently unknown. Its dangers appear to mostly surround inhalation, as it’s generally considered non-toxic for ingestion and skin contact. As with all mineral compounds, however, standard safety precautions should be taken in all situations just in case.
Rutile is of a similar composition to Titanium Dioxide, but is considered an impure form whereby up to 15% of its makeup is contamination from other minerals. If the percentage of additional minerals is any higher than 15% the compound is known as Ilmenite.
Rutile is used more of a glaze modifier than a colourant in its own right, as its presence will increase opacity, encourage crystal growth (in mid to high-temperature firings) and can cause mottling and streaking within the glaze. Due to Rutile often containing a percentage of iron, this can have a dulling or murky effect on certain glazes, and using too much can cause unwanted surface texture and imperfections.
Lead = Straw or Tan Magnesium = Mottled Tan Boron = Tan/Yellow with noticeable streaking and mottling Zinc = Dull Tan with possible crystal growth if the cooling phase is prolonged Barium = Tan/Yellow in oxidisation, Pale Blue in reduction