Calcium Carbonate
Formula: CaCO3
| DENS - Density (Specific Gravity) |
2.80 |
| HMOH - Hardness (Moh) |
3.01 |
| MLPT - Melting Point (MP) |
825C D |
Whiting has traditionally been a source of CaO in raw glazes and glass (however whitings also typically contain some dolomite as a contaminant). Whiting is generally inexpensive and there is a large calcium carbonate industry worldwide for non-ceramic uses of this mineral. Well known deposits are the chalk cliffs of England, France and Belgium. Marble and calcite ores are abundant in many places.
Inexpensive non ceramic grades of whiting tend to lack the quality and consistency needed for use in glazes (especially for industrial use). Also whiting produces a very large volume of gases while decomposing, it loses more than 40% by weight. While these gases should be gone well before 1100C (and therefore should not disturb the glaze melt), in low or fast fire they can contribute to imperfections and faults in the glaze surface. With the advent of faster firing schedules in recent years whiting has been replaced by wollastonite and frits as a source of CaO in many applications (CaO oxide is advantageous in fast fire because it does not lower the melting point as much as the alkalies). Since LOI is a good indicator of variation in chemistry it may be practical to do an LOI test on shipments by firing a specimen of powder in a thin bisqued bowl to confirm the consistency of shipments.
There are many alternate no-LOI sources of CaO (e.g. wollastonite, frits) and incorporating one of them to source the CaO instead is a classic application of ceramic chemistry calculations (it is dealt with in the lessons section of the INSIGHT software manual).
In low-fire bodies, calcium carbonate is sometimes added in small amounts as a filler to reduce fired shrinkage and act as a whitener. It is also common to see 5% whiting included in porous earthenware body recipes to prevent moisture expansion (which causes glazes to craze).
Mechanisms
Out Bound Links
- (Materials - Alternative)
Wollastonite - CaSiO3 - Calcium Silicate
Wolastonite
- (Materials - Parent)
Lime - CALCIUM BEARING MINERALS
Live Calcium
- (Temperatures - Unspecified)
Calcium carbonate decomposition (750C-1000C)
Converts to Quicklime. If burned higher or too lon... - (Hazards - General)
Calcium Carbonate Toxicology
Overview of the hazards associated with the use of... - (Minerals - Mineral equivalent)
Calcite
The pure calcium carbonate crystal mineral. - (Minerals - Parent mineral)
Limestone, Calcium Carbonate
Also called GCC (Ground Calcium Carbonate), limest... - (Typecodes)
1: GNM - Generic Material
- (Typecodes)
1: FLS - Flux Source
- (MDT - Member)
Glass Industry
The materials included in this MDT were selected i... - (MDT - Member)
Crystal Glazes
These materials are specially defined for makers o... - (MDT - Member)
UK
We are working on this database and would apprecia... - (MDT - Member)
Ron Roy
This is the traditional Ron Roy materials file. He... - (Library - Unspecified)
Two Sources of CaO
This is an chapter in the book (and matching video... - (Minerals - Mineral equivalent)
Aragonite
A calcium carbonate mineral with a different cryst... - (MDT - Member)
North America
The decision about what materials to include in th... - (MDT - Member)
New Zealand
We are working on this database and would apprecia... - (MDT - Member)
Latin and South America
Latin America and South America. We are working on... - (MDT - Member)
Europe
Countries of Eastern Europe and former Soviet Unio... - (MDT - Member)
Australia
We are working on this database and would apprecia... - (MDT - Member)
Asia
All of Asia including Turkey, Russia, Indosnesia, ... - (MDT - Member)
Africa
All of continental Africa. We are working on this ...
In Bound Links
Pictures
The top bar is a mix of calcium carbonate and clay fired to cone 6. The bottom is a couple of minutes after water was poured onto it.
Example of calcium carbonate (top) and dolomite (both mixed with 25% bentonite). They are fired to cone 9. Both bars are porous and refractory, even powdery.
XML for Import into INSIGHT
<?xml version="1.0" encoding="UTF-8"?>
<material name="Calcium Carbonate" descrip="" searchkey="Carbonate of Lime, Whiting, Aragonite, Calcite, CaCO3" loi="0.00" casnumber="471-34-1">
<oxides>
<oxide symbol="CaO" name="Calcium Oxide, Calcia" status="U" percent="56.100" tolerance=""/>
</oxides>
<volatiles>
<volatile symbol="CO2" name="Carbon Dioxide" percent="43.900" tolerance=""/>
</volatiles>
</material> | 
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