Kaolin is termed as hydrous when the kaolin has the bound water molecule. The presence of water imparts specific properties that are useful for certain industrial applications. They are generally used as fillers in the paper, paint, glass and rubber industries.

To lose the water molecule and improve colour, the hydrous clay is subjected to high temperatures and the process in known as calcination. The product is termed as calcined clay. The calcination in LP IMPEX  is done in rotary calciners. By controlling the calcination temperature, Metakaolin (550–900°C), Spinel (925–1050°C) or Mullite Phases (>1050°C) of calcined kaolin can be produced.

Metakaolin has applications in cement, rubber, cables & ultramarine blue. The spinel phase is used mainly for paint applications as an extender for TiO2; it also has a few applications for paper, ceramics, polymer and rubber industries. The mullite phase finds its way into the ceramic industry.

Both hydrous and calcined kaolin are utilized for preparation of surface modified kaolin (SMK). The modification is aided by the use of silanes. The SMKs are utilized as functional fillers mainly for rubber and plastic applications to impart specific electrical and mechanical properties. SMKs can be utilized to substitute (fully/partially) the more expensive fillers such as carbon black in the tyre industry.