Silica gel is a spherical bead consisting of 97% silica and 3% alumina. It is available in two types: indicating silica gel, a translucent bead impregnated with blue color and non-indicating silica gel, which is a brown translucent color. Since silica gel desiccant fractures in the presence of liquid water. It must be protected by a 10% to 15% (by weight) layer of activated alumina as a water buffer on the inlet side of the desiccant bed. Dew points to -40°F and lower may be achieved with silica gel depending on dryer design and operating conditions.