Silica gel is a granular, vitreous, porous form of silicon dioxide made synthetically from sodium silicate. It is a naturally occurring mineral that is purified and processed into either granular or beaded form. As a desiccant, it has an average pore size of 2.4 nanometers and has a strong affinity for water molecules.
Silica gel has core of silicon atoms joined together with oxygen atoms by siloxane bonds (silicon-oxygen-silicon bonds). Chemical formula of silica gel is mSiO2, nH2O
The silica gel is manufactured through the reaction between water glass and sulfuric acid, and further gelling, washing, desalting, amidation, drying and screening.

There is mainly two types of silica gel available in market.

Indicating type Silica Gel

In this indicating type silica gel there is also two types of silica gel available in market based on their color changing phenomena.

Blue Indicating Type Silica gel

It appears dark blue in color when free from moisture and gives indication from dark blue to pink when it absorb moisture.cobalt chloride is use for blue to pink indication.

Orange Indicating Type Silica gel

In this type there is also two sub type of Orange Indicating silica gel.

Non Indicating type Silica Gel

t appears in white transparent silica gel. It will not give any clear visual indication of color when it completely hydrated.

It can adsorb moisture 35 to 40% depends on various environmental parameter like Temperature,humidity, and Air flow.