1-9 | A | B | C | D | E | F | Frits | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Jordan Fireclay

Alternate Names: Maryland Ball/Stoneware Clay

Oxide Analysis Formula
CaO 0.20% 0.02
K2O 1.99% 0.11
MgO 0.50% 0.06
Na2O 0.20% 0.02
TiO2 1.20% 0.08
Al2O3 20.18% 1.00
SiO2 67.23% 5.65
Fe2O3 1.71% 0.05
Oxide Weight 471.13
Formula Weight 505.40


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.

Related Information

Jordan Fireclay fired test bars

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


Materials Fireclay
Typecodes Clay Other
Clays that are not kaolins, ball clays or bentonites. For example, stoneware clays are mixtures of all of the above plus quartz, feldspar, mica and other minerals. There are also many clays that have high plasticity like bentonite but are much different mineralogically.
Typecodes Fireclay
Fireclays are non-kaolin non-ball clay materials similar to stoneware clays but lacking fluxing oxides. Many fireclays have a PCE of 28 or more.


Firing ShrinkageCone 1: 5.2% Cone 5: 6.7%
Frit Softening Point3020F
Ultimate Particle Size Distribution10 microns: 61.5% 5: 51.5% 2: 40% 1: 31.5% 0.5: 22.5%
Pyrometric Cone Equivalent26-27
Water absorptionCone 1: 6.6% Cone 5: 3.4%

By Tony Hansen

Tell Us How to Improve This Page

Or ask a question and we will alter this page to better answer it.

Email Address




Upload picture

Copyright 2008, 2015, 2017 https://digitalfire.com, All Rights Reserved