•The secret to cool bodies and glazes is a lot of testing.
•The secret to know what to test is material and chemistry knowledge.
•The secret to learning from testing is documentation.
•The place to test, do the chemistry and document is an account at https://insight-live.com
•The place to get the knowledge is https://digitalfire.com

Sign-up at https://insight-live.com today.

Calvert Clay

Red Burning Clay

Oxide Weight394.37
Formula Weight428.57
If this formula is not unified correctly please contact us.
PCE - Pyrometric Cone Equivalent 29-30
WABS - Water absorption Cone 1: 1.4% Cone 5: 0.3
FSHR - Firing Shrinkage Cone 1: 8.9% total Cone 5: 9.1 (overfired)
UPSD - Ultimate Particle Size Distribution 10 microns: 89% 5: 84% 2: 67% 1: 54% 0.5: 43%

A description we have inherited (but do not know from where) is that this is "a red burning material used in the formulation of clay bodies to provide maturity and color at all temperature ranges". This description is impossible, no clay can provide maturity at all temperatures, and the chemistry we have indicates that it would not be a mature-firing material at common kiln firing ranges.

We have no indication of its physical working properties (e.g. plasticity, drying shrinkage, texture). We do not currently have a source for any other physical data. That data shown here is likely not correct (a clay with a PCE of 30 would not have 1.4% porosity at cone 1)! That being said, a clay with this chemistry would be more refractory that is shown by this data also).

Based on the chemistry this appears to be a fairly refractory material (however it has enough fluxes that it is not likely a fireclay). It has fairly high Al2O3 content so likely has some kaolin content. Redart, a low-firing material, would likely not be a good substitute in a recipe. Fire-Red from Plainsman Clays, is likely a little more refractory. Plainsman Redstone is likely less refractory.

Out Bound Links

By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="Calvert Clay" descrip="Red Burning Clay" searchkey="" loi="0.00" casnumber="70694-09-6"> <oxides> <oxide symbol="CaO" name="Calcium Oxide, Calcia" status="" percent="0.300" tolerance=""/> <oxide symbol="MgO" name="Magnesium Oxide, Magnesia" status="" percent="0.800" tolerance=""/> <oxide symbol="K2O" name="Potassium Oxide" status="" percent="2.000" tolerance=""/> <oxide symbol="Na2O" name="Sodium Oxide, Soda" status="" percent="0.410" tolerance=""/> <oxide symbol="TiO2" name="Titanium Dioxide, Titania" status="" percent="1.210" tolerance=""/> <oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="23.800" tolerance=""/> <oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="57.790" tolerance=""/> <oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="5.710" tolerance=""/> </oxides> <volatiles> <volatile symbol="LOI" name="Loss on Ignition" percent="7.980" tolerance=""/> </volatiles> </material>

Feedback, Suggestions

Your email address


Your Name


Copyright 2003, 2008, 2015 https://digitalfire.com, All Rights Reserved