Rutile

Iron Titanium Mineral

Chemistry

TiO292.000
ZrO21.000
Al2O30.300
Fe2O36.500

Volatiles

LOI0.100

Links to Other Materials

Miscellaneous

Notes

Rutile is the mineral name for natural crystals of titanium dioxide. However in nature rutile is always contaminated by up to 15% other minerals (especially iron but also things like tantalum, niobium, chromium and tin). The term 'rutile' is thus generally understood to refer to the brown powder into which these minerals are ground and industry accepts up to 15% contaminants and yet still calls it rutile (below 85% titanium is called ilmenite). Rutile is considered an impure form of titanium whereas ilmenite is considered as FeTiO3. Grades of rutile are sometimes named after one of the impurities (e.g. Niobian Rutile). Rutile is used in many industries (e.g. welding rods, paint) and ceramic uses are minor in comparison (for this reason bags of rutile might have labels like "Welding Rod Titanate"). Rutile is often sourced by companies in the titania and zircon supply business. The are large reserves of rutile in the world and any supply shortages are thus related to other factors.

Rutile is a very hard (6-6.5 Moh) and heavy titanium mineral mined in Australia, Africa, Norway, Canada, and in Florida and NY in USA. With the many companies processing it and the numerous sources it is not unexpected that stocks at ceramic suppliers can be variable. Variations in material can also a result of changes within a deposit at one mine (more on this in a moment).

Australia has very large deposits and many companies are mining them. The rutile there was produced by the weathering of granite and other igneous rocks along the seashore. The action of waves breaks down the rocks and the heavy rutile particles sediment while the lighter mineral particles are washed away. The deposits are thus in the form of beach sands. In other areas rutile is processed from materials from hard rock mines such as in Virginia and Quebec, Canada. It is possible to purify ilmenite and rutile to higher concentrations of titania and reduce iron to much less than 1%.

Rutile is available in light calcined ceramic grade powder (very fine particle size), dark uncalcined powder, and granular form. Either grade of powder can be ground very fine (e.g. 325 mesh). In glazes it is generally better to use the ceramic grade since the decomposition of raw rutile during firing can be a source of glaze imperfections like pinholing and bubbles (even larger amounts of the ceramic grade, e.g. 8%, can also cause problems).

Rutile produces many crystalline, speckling, streaking, and mottling effects in glazes during cooling in the kiln and has been used in all types of colored glazes to enhance the surface character. It is thus highly prized by potters, many attractive variegated glazes are made using it. Many potters would say that their living depends on their rutile supply!

This material can be inconsistent in the amount of iron and impurities producing variations in color and surface character, thus manufacturers will blend ores from different deposits (Ferro in the US blends various Australian materials in addition to material from Florida). For example, one major American supplier, TAM (now Ferro), relied on a high quality Sierra Leonian rutile deposit until 1995 when political problems in the country cut the supply. Since then no other substitute has provided the same quality. Considering that it is the metallic coloring impurities in rutile that are the subject of its variation and that the function of rutile in glazes is most often partly or mainly as a colorant, it is easy to see that visual consistency variations can be expected when using this material in ceramic glazes. Large users of rutile will often track batch numbers from the manufacturer and test when the number changes. If serious differences are detected another batch may be requested. Failing this the situation can sometimes be dealt with by adjusting the amount of rutile in the recipe or firing differently. In more serious situations adjusting the recipe and employing other materials like iron and titanium might be needed. In any case, it is important to understand the base glaze and the mechanisms by which rutile imparts the desired visual effect. Buying large amounts of a batch that works well is thus a good idea with a material like rutile.

In ceramic glazes rutile is more often considered a variegator than a colorant. As little as 2% can impart significant effects in stoneware glazes. It is normally used in combination with a wide range of metal oxide and stain colorants to produce surfaces that are much more visually interesting. In glazes with high melt fluidity (e.g. having high boron), large amounts of rutile (e.g. 8%) can be quite stunning. The rutile encourages the development of micro-crystals and rivulets. Since rutile contains significant iron its use in combination with other colorants will often muddy the color that they would otherwise have or alter it if they are sensitive to the presense of iron. Even though rutile generally makes up less than 5% of stoneware glazes that employ it, they are often called 'rutile glazes' in recognition of its dramatic contribution.

Excessive rutile in a glaze can produce surface imperfections. In addition, when rutile is employed in higher percentages (e.g. 5%+) a given percentage might work well whereas a slightly higher amount can look drastically different. Such situations are vulnerable to chemistry changes in the supply of rutile. Thus people will often do a line blend trying a range of percentages to determine an optimal amount.

In glazes rutile can be quite sensitive to the presence of opacifiers. While an unopacified glaze glaze might appear quite stunning, the addition of a zircon opacifier will usually drastically alter its appearance and interest because the variegation imparted is dependent on the glaze having depth and transparency or translucency. Strangely rutile and tin, another opacifier, can produce some very interesting reactions and it is quite common to see tin in amounts of up to 4% in rutile glazes. In these cases the tin appears to react in the crystal formation rather than opacify the glaze.

Rutile powder, although its color makes it appear to be a very crude ground mineral, normally contains 90%+ titanium dioxide. However this does not mean that you can use a 90% titanium:10% iron mix and get the same result in a ceramic glaze (obviously line blending would be needed to match the amount of iron). The mineralogy and significant other impurities in rutile are a major factor in the way it acts in glazes and are not easily duplicated using a blend of other things. Sometimes the special effects that rutile produces in glazes are also partly a product of a coarser grade (larger particle size). These likewise cannot be easily duplicated by more refined materials. Unfortunately the trend at some mining operations (at least in Australia) is to fine grind the rutile on-site, making it more difficult for ceramic operations to obtain the coarser grades.

Although rutile will normally stain a glaze brown or yellow, its crystallization effects can significantly lighten the color of iron glazes. Higher amounts of rutile in stoneware glazes will often contribute glaze imperfections.

Granular rutile is sometimes used in bodies and glazes to impart fired speckle.

Rutile is used for special effects in leaded glazes and can form up to 15% of the recipe.

Rutile can be used as a tone modifier to soften the more potent colorants.

Suppliers: F & S Alloys & Minerals, New York 212-490-1356 FAX 557-8457
Fusion Ceramics, Carrollton, OH 216-627-2191 FAX 627-2082
Hammill & Gillespie Inc., Livingston, NJ 201-994-3650 FAX 994-3847
Tam Ceramics, Niagara Falls 716-278-9400 FAX 285-3026

(Richard Willis)

Mineral,TiO2,with a typical empirical analysis of Ti 59.95%, O2 40.05%
Hardness: 6-6.5 Density: 4.2-4.3 Insoluble in acids
The metal crystals commonly coating welding rods. In pottery TiO2 is one of the most common ways of introducing titanium to a recipe. Strong refractory and opacifier. see brookite, ilmenite, sagenite

Properties

Data

Linked Articles

URLs

Suppliers

Authors

Pictures

XML

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<material name="Rutile" descrip="Iron Titanium Mineral" generic="1" rawmineral="1" searchkey="Iron Titanate" loi="0.10">
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<oxide symbol="TiO2" name="Titanium Dioxide, Titania" status="U" percent="92.000" tolerance=""/>
<oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="0.300" tolerance=""/>
<oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="6.500" tolerance=""/>
<oxide symbol="ZrO2" name="Zirconium Dioxide" status="" percent="1.000" tolerance=""/>
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<note>Rutile is the mineral name for natural crystals of titanium dioxide. However in nature rutile is always contaminated by up to 15% other minerals (especially iron but also things like tantalum, niobium, chromium and tin). The term \'rutile\' is thus generally understood to refer to the brown powder into which these minerals are ground and industry accepts up to 15% contaminants and yet still calls it rutile (below 85% titanium is called ilmenite). Rutile is considered an impure form of titanium whereas ilmenite is considered as FeTiO3. Grades of rutile are sometimes named after one of the impurities (e.g. Niobian Rutile). Rutile is used in many industries (e.g. welding rods, paint) and ceramic uses are minor in comparison (for this reason bags of rutile might have labels like &quot;Welding Rod Titanate&quot;). Rutile is often sourced by companies in the titania and zircon supply business. The are large reserves of rutile in the world and any supply shortages are thus related to other factors.

Rutile is a very hard (6-6.5 Moh) and heavy titanium mineral mined in Australia, Africa, Norway, Canada, and in Florida and NY in USA. With the many companies processing it and the numerous sources it is not unexpected that stocks at ceramic suppliers can be variable. Variations in material can also a result of changes within a deposit at one mine (more on this in a moment).

Australia has very large deposits and many companies are mining them. The rutile there was produced by the weathering of granite and other igneous rocks along the seashore. The action of waves breaks down the rocks and the heavy rutile particles sediment while the lighter mineral particles are washed away. The deposits are thus in the form of beach sands. In other areas rutile is processed from materials from hard rock mines such as in Virginia and Quebec, Canada. It is possible to purify ilmenite and rutile to higher concentrations of titania and reduce iron to much less than 1%.

Rutile is available in light calcined ceramic grade powder (very fine particle size), dark uncalcined powder, and granular form. Either grade of powder can be ground very fine (e.g. 325 mesh). In glazes it is generally better to use the ceramic grade since the decomposition of raw rutile during firing can be a source of glaze imperfections like pinholing and bubbles (even larger amounts of the ceramic grade, e.g. 8%, can also cause problems).

Rutile produces many crystalline, speckling, streaking, and mottling effects in glazes during cooling in the kiln and has been used in all types of colored glazes to enhance the surface character. It is thus highly prized by potters, many attractive variegated glazes are made using it. Many potters would say that their living depends on their rutile supply!

This material can be inconsistent in the amount of iron and impurities producing variations in color and surface character, thus manufacturers will blend ores from different deposits (Ferro in the US blends various Australian materials in addition to material from Florida). For example, one major American supplier, TAM (now Ferro), relied on a high quality Sierra Leonian rutile deposit until 1995 when political problems in the country cut the supply. Since then no other substitute has provided the same quality. Considering that it is the metallic coloring impurities in rutile that are the subject of its variation and that the function of rutile in glazes is most often partly or mainly as a colorant, it is easy to see that visual consistency variations can be expected when using this material in ceramic glazes. Large users of rutile will often track batch numbers from the manufacturer and test when the number changes. If serious differences are detected another batch may be requested. Failing this the situation can sometimes be dealt with by adjusting the amount of rutile in the recipe or firing differently. In more serious situations adjusting the recipe and employing other materials like iron and titanium might be needed. In any case, it is important to understand the base glaze and the mechanisms by which rutile imparts the desired visual effect. Buying large amounts of a batch that works well is thus a good idea with a material like rutile.

In ceramic glazes rutile is more often considered a variegator than a colorant. As little as 2% can impart significant effects in stoneware glazes. It is normally used in combination with a wide range of metal oxide and stain colorants to produce surfaces that are much more visually interesting. In glazes with high melt fluidity (e.g. having high boron), large amounts of rutile (e.g. 8%) can be quite stunning. The rutile encourages the development of micro-crystals and rivulets. Since rutile contains significant iron its use in combination with other colorants will often muddy the color that they would otherwise have or alter it if they are sensitive to the presense of iron. Even though rutile generally makes up less than 5% of stoneware glazes that employ it, they are often called \'rutile glazes\' in recognition of its dramatic contribution.

Excessive rutile in a glaze can produce surface imperfections. In addition, when rutile is employed in higher percentages (e.g. 5%+) a given percentage might work well whereas a slightly higher amount can look drastically different. Such situations are vulnerable to chemistry changes in the supply of rutile. Thus people will often do a line blend trying a range of percentages to determine an optimal amount.

In glazes rutile can be quite sensitive to the presence of opacifiers. While an unopacified glaze glaze might appear quite stunning, the addition of a zircon opacifier will usually drastically alter its appearance and interest because the variegation imparted is dependent on the glaze having depth and transparency or translucency. Strangely rutile and tin, another opacifier, can produce some very interesting reactions and it is quite common to see tin in amounts of up to 4% in rutile glazes. In these cases the tin appears to react in the crystal formation rather than opacify the glaze.

Rutile powder, although its color makes it appear to be a very crude ground mineral, normally contains 90%+ titanium dioxide. However this does not mean that you can use a 90% titanium:10% iron mix and get the same result in a ceramic glaze (obviously line blending would be needed to match the amount of iron). The mineralogy and significant other impurities in rutile are a major factor in the way it acts in glazes and are not easily duplicated using a blend of other things. Sometimes the special effects that rutile produces in glazes are also partly a product of a coarser grade (larger particle size). These likewise cannot be easily duplicated by more refined materials. Unfortunately the trend at some mining operations (at least in Australia) is to fine grind the rutile on-site, making it more difficult for ceramic operations to obtain the coarser grades.

Although rutile will normally stain a glaze brown or yellow, its crystallization effects can significantly lighten the color of iron glazes. Higher amounts of rutile in stoneware glazes will often contribute glaze imperfections.

Granular rutile is sometimes used in bodies and glazes to impart fired speckle.

Rutile is used for special effects in leaded glazes and can form up to 15% of the recipe.

Rutile can be used as a tone modifier to soften the more potent colorants.

Suppliers: F &amp; S Alloys &amp; Minerals, New York 212-490-1356 FAX 557-8457
Fusion Ceramics, Carrollton, OH 216-627-2191 FAX 627-2082
Hammill &amp; Gillespie Inc., Livingston, NJ 201-994-3650 FAX 994-3847
Tam Ceramics, Niagara Falls 716-278-9400 FAX 285-3026</note>
<note>Mineral,TiO&lt;FONT SIZE=2&gt;&lt;SUB&gt;2&lt;/SUB&gt;&lt;/FONT&gt;&lt;SUB&gt;,&lt;/SUB&gt;with a typical empirical analysis of&lt;SUB&gt; &lt;/SUB&gt;Ti 59.95%, O&lt;FONT SIZE=2&gt;&lt;SUB&gt;2&lt;/SUB&gt;&lt;/FONT&gt; 40.05%&lt;SUB&gt;
&lt;/SUB&gt;Hardness: 6-6.5 Density: 4.2-4.3 Insoluble in acids
The metal crystals commonly coating welding rods. In pottery TiO&lt;FONT SIZE=2&gt;&lt;SUB&gt;2&lt;/SUB&gt;&lt;/FONT&gt; is one of the most common ways of introducing titanium to a recipe. Strong refractory and opacifier.&lt;SUB&gt; &lt;/SUB&gt;&lt;FONT SIZE=2&gt;see &lt;B&gt;&lt;I&gt;brookite, ilmenite&lt;/I&gt;&lt;/B&gt;,&lt;B&gt;&lt;I&gt; sagenite&lt;/I&gt;&lt;/B&gt;&lt;/FONT&gt;</note>
</notes>
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<pictures>
<picture description="2,3,4,5% rutile added to a 80:20 mix of Alberta Slip and Frit 3134 at cone 6" filename="g2862-431x170-6.jpg"/>
<picture description="Phonolite Rutile" filename="phonolite_rutile.jpg"/>
<picture description="Quartz Rutilated" filename="quartz_rutilated.jpg"/>
<picture description="Rutilated Quartz" filename="rutilated_quartz.jpg"/>
<picture description="Rutilated Quartz2" filename="rutilated_quartz2.jpg"/>
<picture description="Rutile Crystals" filename="rutile_crystals.jpg"/>
<picture description="Rutilite Slices" filename="rutilite_slices.jpg"/>
</pictures>
</material>


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