Extremely tough material for ceramics and refractories

Chamotte—also known as ‘grog’, ‘firesand’ or “fireclay”—is calcined clay containing a high proportion of alumina. It is produced by firing selected fire clays in a rotary kiln to temperatures between 1,400°C and 1,600°C, before grinding and screening to specific particle sizes.

For ceramics, typical chamotte contains 40% minimum alumina, 30% minimum silica, 4% maximum iron oxide, and up to 2% calcium oxide and magnesium oxide combined. The particle size distribution is generally coarser in size than the other raw materials used to prepare sanitaryware bodies for instance.

For refractories, chamotte contains from 38% to 48% alumina in general. Iron is generally limited to 2.5% and alkalies must be also limited in amount to preserve refractoriness and thermal stability at temperatures up to 1400°C.

Highly resistant to extreme temperatures, harsh operating conditions, mechanical failure, and corrosion, chamotte is a crucial ingredient in the production of ceramics—in particular sanitaryware—and refractories.

Chamotte grains have been treated at very high temperatures, which means that they will be stable when fired at a slightly lower temperature. They are used to make up the rigid skeleton of ceramics and refractories at high temperatures, limiting shrinkage due to sintering.