Most ceramic bodies are made from three groups of minerals: clay, feldspar and quartz. Clay makes the body plastic and strong before firing, feldspar melts in the kiln and binds the body, and quartz gives a stable skeleton that controls shrinkage.
The mix decides what the product becomes. Change the proportions and the firing, and the same three materials can make a porous wall tile, a dense vitrified tile or a WC.
Clay
Clay is the base. When wet it can be pressed or cast. When dry it holds its shape. Two types matter most.
- Ball clay is fine and plastic. It gives green strength, so pressed tiles do not break before firing.
- Kaolin, also called china clay, is whiter and less plastic. It gives a lighter fired colour and is used where whiteness matters.
- Red clays contain more iron and fire to a red or brown colour; they are used in roof tiles and red-body wall tiles.
- Bentonite is sometimes added in small amounts to raise plasticity.
Feldspar
Feldspar is the flux. In the kiln it melts into a glass that fills the gaps between particles and binds them. This is what makes a vitrified tile dense and gives it a water absorption of 0.5% or less.
Sodium feldspar melts at a lower temperature and more sharply. Potassium feldspar melts more gradually, which helps the body hold its shape. Factories choose or blend them to suit the kiln.
Quartz
Quartz, often supplied as silica sand or ground quartz, does not melt much at tile firing temperatures. It forms the skeleton of the body and reduces shrinkage and warping.
Too much quartz can make a body brittle or cause cracking as it cools, because quartz changes volume at certain temperatures. Getting the balance right is part of the factory's know-how.
Other materials
- Calcite, dolomite or wollastonite are used in some wall tile bodies to keep them porous and stable.
- Talc is added to some bodies as an extra flux.
- Deflocculants such as sodium silicate help the clay slurry flow with less water before spray drying or casting.
- Frit, zirconium silicate and colours go into the glaze and engobe, not the body; see what ceramic glazes and engobes are.
Why buyers should care
Raw materials explain many quality differences between factories. A plant using cleaner clay and well-processed feldspar can make a whiter, more even body. That matters most for full-body tiles and slabs, where the body shows through. See what a full-body vitrified tile is.
Raw material changes also cause shade and size shifts between batches. Ask factories how they check incoming materials and how long they keep a stockpile of the same source.
If you want to buy the minerals themselves, see whether you can source ceramic raw materials from Gujarat.
Next step
Our factory audits look at raw material storage and incoming checks, because they predict consistency. To discuss your range, book a free sourcing review.