Digitalfire Ceramic Materials Database

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Alternate Names: Bentone MA

Oxide Weight120.43
Formula Weight140.14
Enter the formula and formula weight directly into the Insight MDT dialog (since it records materials as formulas).
Enter the analysis into an Insight recipe and enter the LOI using Override Calculated LOI (in the Calc menu). It will calculate the formula.

Bentone MA is a highly refined hectorite clay that can be used as a body plasticizer and a glaze suspension agent. At one time it was known as Macaloid, and many resellers in the pottery and hobby supply industry still refer to is by this name.

The material is used as a substitute for bentonite in porcelain bodies (it contains so little iron oxide that it burns pure white). Bentone MA contributes to increased plasticity but also to greater shrinkage due to its higher absorption of water. It should always be mixed well with warm water before adding to a glaze or clay body. It is almost always used in quantities of less than 3% of the total mass of the glaze or clay body.

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Bentone (A.K.A. Macaloid MA) is a very plastic highly refined hectorite clay. This specimen has been mixed as a slurry, then dewatered until plastic on a plaster slab (it is very resistant to giving up its water). The plastic material has a very high water content, is exceptionally sticky and took many days to dry from the plastic stage. It shrinks 30% or more from plastic to fired and burns pure white at cone 6 (it can withstand higher temperatures). It burns whiter than similar materials from other manufacturers.

Veegum (left), Mineral Colloid and Gelwhite fired to cone 6 oxidation. The Veegum is dense and white, but not melting. The Mineral Colloid fires like a typical raw bentonite (dark brown, high soluble salts and beginning to melt). The Gelwhite is completely melted and foamed.

The glass on the small tile at the right drained out from this specimen of Macaloid as it was fired at cone 6.

By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="Macaloid" descrip="" searchkey="Bentone MA" loi="0.00" casnumber=""> <oxides> <oxide symbol="CaO" name="Calcium Oxide, Calcia" status="" percent="6.460" tolerance=""/> <oxide symbol="MgO" name="Magnesium Oxide, Magnesia" status="" percent="22.070" tolerance=""/> <oxide symbol="Na2O" name="Sodium Oxide, Soda" status="" percent="3.080" tolerance=""/> <oxide symbol="TiO2" name="Titanium Dioxide, Titania" status="" percent="1.210" tolerance=""/> <oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="0.770" tolerance=""/> <oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="51.890" tolerance=""/> <oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="0.320" tolerance=""/> </oxides> <volatiles> <volatile symbol="SO4" name="Sulfate" percent="2.070" tolerance=""/> <volatile symbol="LOI" name="Loss on Ignition" percent="12.000" tolerance=""/> </volatiles> </material>

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