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Silverline 303 Talc

MONTANA TALC

OxideAnalysisFormula
CaO1.00%0.023
MgO31.00%0.977
Al2O30.50%0.006
SiO262.00%1.311
Fe2O30.50%0.004
LOI5.00
Oxide Weight120.70
Formula Weight127.06
If this formula is not unified correctly please contact us.
DENS - Density (Specific Gravity) 2.8
GEBR - GE Brightness 74-82
HEGF - Hegman Fineness 3.0-4.0
P325 - % Passing 325 Mesh Wet 99.5%

Silverline 325 is a 325 mesh, asbestos free, platy Montana talc. It is intended for use as a general purpose talc filler where high brightness is not required so their current data sheet does not show the chemistry (however we have it from a prior one). It certainly does have suitable properties for ceramic applications, though it is not actively promoted for ceramics.

It is useful in ceramics as a flux for middle temperature bodies, 2-3% can reduce maturing temperature by 2-3 cones. The iron content is high enough that this talc will yellow the color of white earthenware casting bodies (these typically employ 50% talc).

Physical Properties:
% Passing 200 mesh (74 micron): 100
325 mesh (44 micron): 98
-20 micron: 79%
-10 micron: 57%
-5 micron: 38%
-1 micron: 7%
Median particle size: 7.5 micron

Oil Absorption g/100g talc (ASTM D281): 29
Bulk Density (lbs per cubic ft) Loose: 16 Tapped: 32
Specific Gravity: 2.8

Mineralogy:
Talc 97%
Dolomite 2%
Chlorite <1%
Quartz <1%

Asbestiform Mineral Test: CTFA J 4-1

Here is a grade comparison between the various Montana Talc products made by Imerys Talc:

Yellowstone: Microcrystalline 200 mesh. Excellent for steatite insulators and as a flux for high alumina ceramics.
Steawhite 2: 200 mesh steatite talc that fires off-white. Low alkali and low iron content. Excellent for electrical porcelain / glazes and color sensitive steatite applications.
Luzenac 2C: Unique talc-chlorite mineral that contains relatively high amounts of aluminum in the crystal lattice. Used in cordierite applications, sanitaryware flux, white-body floor tile and vitreous china.
Sierralite 252HS:Chlorite with high alumina content and low iron oxide content. Used in ceramics and refractory materials requiring low thermal expansion and good thermal shock resistance.


Texas talc (left) and Montana talc (right). Texas talc contains some amorphous carbon. The carbon is not stand-alone, but as CO2 in the dolomitic part of the ore. It produces 7% LOI between 750-850C.

Silverline Talc bags are now labelled Imerys Talc. The company was bought by Imerys.

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By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="Silverline 303 Talc" descrip="MONTANA TALC" searchkey="" loi="0.00" casnumber="14807-96-6"> <oxides> <oxide symbol="CaO" name="Calcium Oxide, Calcia" status="" percent="1.000" tolerance=""/> <oxide symbol="MgO" name="Magnesium Oxide, Magnesia" status="" percent="31.000" tolerance=""/> <oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="0.500" tolerance=""/> <oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="62.000" tolerance=""/> <oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="0.500" tolerance=""/> </oxides> <volatiles> <volatile symbol="LOI" name="Loss on Ignition" percent="5.000" tolerance=""/> </volatiles> </material>


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