Refractory clay is the main raw material to produce clay firebricks. The clay particles that constitute clay have very small scales -- no more than 5P (micron). Because of the high dispersion of the particles and some characteristics of the structure of the particles, the clay water permeable sometimes has the function of plastic mud. Plasticity can be understood as the function of changing the shape of a material when it is acted on by external force and sticking to the shape when the external force stops acting.

The plasticity of clay refractory brick is mainly determined by raw clay, during which the main elements are:

1. The size of clay particles is small.

2. The lamellar structure of clay particles.

The clay particles are surrounded by a tight film of water.

Clay refractory clay is malleable only under wetting conditions. When water is gradually added to clay, the plasticity is weak at first, increases as water continues to be added, reaches its maximum, then begins to decrease, and finally disappears completely as the clay mass becomes liquid. The state at which the clays are most malleable will be code consistency, which is determined by the weight of the water (usually the code water content).