|Monthly Tech-Tip |
Processed rutile ore (upgraded to 95%+ TiO2 by smelting). Available in a variety of sizes. It can be used at a speckling agent in glazes, however it settles quickly because of the high specific gravity. It can also be used as a speckling agent in bodies, try around 0.2% to start.
Yes, the granular and powdered grades or pure rutile are the same material. But grinding it is very difficult. Commercial ceramic grade powder is minus 325 mesh, the companies doing this obviously have very good grinding equipment. They also have patience because even in this efficient porcelain ball mill, 90 minutes was only enough to get 50% to minus 325 mesh! The color of the powder is a good indication of its quality, the finer the grind the lighter tan it will be.
Clearly, the manganese is blossoming and producing far better speckle than the other two.
Metallic based materials that impart fired color to glazes and bodies.
A raw TiO2-containing mineral used in ceramics to color and variegate glaze surfaces.
In ceramics, it is used primarily in clays and glazes to achieve fired speckle (including the brick industry).
Rutile mineral ground to a very fine particle size (e.g. 325 mesh) contributes titanium and iron that colors and variegates ceramic glazes.
|Glaze Variegation||Granular rutile is popular as a specking agent. Start with 0.2%. This material is heavy and will settle in glaze with a thin slurry.|
|By Tony Hansen|
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