Mika Sillanpää, Amit Bhatnagar, in Natural Organic Matter in Water, 2015. 7.3.1 Silica Gel. Silica gel is most commonly encountered in everyday life as beads in a small paper packet. In this form, it is used as a desiccant to control local humidity to avoid spoilage or degradation of some goods. Silica gels are classified into three types: regular, intermediate, and low density gels.