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Titanium Dioxide
Anatase, Brookite
Chemistry
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Miscellaneous
- Family: Opacifier
- Region: North America
- Mined At: Unspecified
- Raw Mineral: No
- Generic: Yes
Notes
TiO2 occurs in many silicates in nature, accounting for over 1% of the earth's crust. Thus it is manufactured using a variety of materials and processes.
Although titanium is the strongest white pigment known for many uses, in ceramics the whiteness (and opacity) it imparts to glazes is due to its tendency to crystallize during cooling. Although titanium dioxide is used in glazes as an opacifier, it is not as effective and easy-to-use as tin oxide or zircon. It can be used as an additive to enliven (variegate, crystallize) the color and texture of glazes (rutile works in a similar manner). In moderate amounts it encourages strong melts, durable surfaces and rich visual textures.
Titanium is available both as raw and surface treated products. Non-pigmentary grades flow more freely in the dry state. Self opacified enamels are made by adding titanium during smelting to super saturation. Upon firing the enamel, the titanium crystallizes or precipitates to produce the opacity. Titania is also used in dry process enameling on cast iron appliances for its effect on acid resistance, color and texture. In glass, non-pigmentary titanium dioxide increases refractive index, intensifies color.
Properties
Glaze Opacifier - White
Titanium is a crystalline mineral and encourages crystal development during cooling and freezing of the glaze melt. This generally produces opacity. However, titanium opacified glazes have a much different character than zircon or tin types. The latter produces a much more even and bright white coloration. When used as an opacifier the batch amount can range to 10% or more of the recipe.Surface Modifier - Matte
Titanium can be used in glazes to produce a matte surface with increasing amounts of crystallization in amounts up to 25%. The effect works in most stoneware glazes and is best when the glaze is slow cooled.Surface Modifier - Variegation
Smaller amounts of titanium dioxide (i.e. 5%) added to colored or opacified recipes can variegate the surface and make it more interesting (e.g. it alters the shape of crystals, shade of colors).
Data
- Melting Point (MP): 1830C
- Specific Gravity: 4.26
- Hardness (Moh): 6.5
- Hardness (Moh): 6.5
- Specific Gravity: 4.26
- Melting Point (MP): 1830C
URLs
- Interesting deposit in South America - http://www.inminex.com/
Suppliers
- Ferro Corporation
- Kerr-McGee Corporation
- Whittaker Clark & Daniels Inc
Authors
- Tony Hansen (Owner)
XML
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