About Silica Gel 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. It is used as a desiccant to control local humidity in order to avoid spoilage or degradation of some goods. Because of its high surface area allows it to absorb water readily, making it useful as a desiccant (drying agent). Once saturated with water, the gel can be regenerated by heating it to 120 °C (250 °F) for two hours.