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Jordan Fireclay

Low Iron Fireclay

Alternate Names: Maryland Ball/Stoneware Clay

Oxide Weight471.13
Formula Weight505.40
If this formula is not unified correctly please contact us.
PCE - Pyrometric Cone Equivalent 26-27
GSPT - Frit Softening Point 3020F
WABS - Water absorption Cone 1: 6.6% Cone 5: 3.4%
FSHR - Firing Shrinkage Cone 1: 5.2% Cone 5: 6.7%
UPSD - Ultimate Particle Size Distribution 10 microns: 61.5% 5: 51.5% 2: 40% 1: 31.5% 0.5: 22.5%

A popular raw material for pottery clay bodies for many years. There is some confusion about the claimed physical properties of this material (the chemistry and firing absorption and shrinkage do not match with our own testing of the material). We found that by itself it has a drying shrinkage of more that 7%, which is a little too high for typical pottery clay bodies. We found it had excellent drying properties in spite of the high shrinkage (it scored A000 on the DFAC test). It had a 1% fired porosity at cone 6 and reached zero % around cone 7. It should be possible to make a pottery clay from Jordan fireclay as 100% of the mix and it should be serviceable around cone 5 to give some margin for error of over firing. However adding 25% kaolin should improve it somewhat, reducing shrinkage and increasing the maturing range to cone 6.

This material is known to contain natural feldspar fluxes, this resists the growth of cristobalite during firing, thus resisting shivering and thermal shock failure. Strangely, the chemistry from the manufacturer does not suggest this either.

Jordan Fireclay fired test bars

Jordan Fireclay fired test bars

Cone 6 to 10 oxidation (top to bottom) fired shrinkage and porosity testing bars.

Out Bound Links

By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="Jordan Fireclay" descrip="Low Iron Fireclay" searchkey="Maryland Ball/Stoneware Clay" loi="0.00" casnumber="70694-09-6"> <oxides> <oxide symbol="CaO" name="Calcium Oxide, Calcia" status="" percent="0.200" tolerance=""/> <oxide symbol="MgO" name="Magnesium Oxide, Magnesia" status="" percent="0.500" tolerance=""/> <oxide symbol="K2O" name="Potassium Oxide" status="" percent="1.990" tolerance=""/> <oxide symbol="Na2O" name="Sodium Oxide, Soda" status="" percent="0.200" tolerance=""/> <oxide symbol="TiO2" name="Titanium Dioxide, Titania" status="" percent="1.200" tolerance=""/> <oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="20.180" tolerance=""/> <oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="67.230" tolerance=""/> <oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="1.710" tolerance=""/> </oxides> <volatiles> <volatile symbol="LOI" name="Loss on Ignition" percent="6.780" tolerance=""/> </volatiles> </material>

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