There are two methods to prepare white carbon black, namely calcination method and precipitation method.

The white carbon black prepared by calcination method is also called gas phase white carbon black or dry process white carbon black. It is prepared by gas phase reaction with polyhalogenated silicon (SiClx) as raw material through thermal decomposition at high temperature.

The particle size of dry white carbon black is very small, about 15~25nm, and the flying property is very high. The fumed silica has few impurities and good reinforcement, but its preparation is complex and costly. It is mainly used in silicone rubber. The products obtained are transparent and translucent. The physical and mechanical properties and dielectric properties of the products are good, and the water resistance is excellent.

Precipitation method Silica hydrate is generally prepared by neutralization and precipitation reaction of silicate (usually sodium silicate) and inorganic acid (usually sulfuric acid).

Precipitation silica has a large particle size, about 20~40nm, low purity, poor reinforcement compared with calcination method. The dielectric property of rubber compound, especially after being damped, is poor, but the price is cheap and the process performance is good. It can be used alone in NR, SBR and other general-purpose rubbers, or used together with carbon black to improve the flex cracking resistance of the rubber compound and slow down the crack growth.