Silica gels, which are actually quite solid and not gel like in texture, are made from sodium silicate. It is made synthetically to be an exceptionally porous and granular form of silica. Although silica is a naturally occurring substance, by extensive processing and chemical modification, its physical characteristics can be modified and applied to a large variety of uses.
One of its major uses is as a silica gel packets used as a desiccant. Silica gel works as a desiccator of various goods and can be put to use in different forms: more specifically, various shapes and sizes. It has a long history; the synthetic route for chemically altering silica into silica gels (to be used generally as a desiccant) was patented by Walter A. Patrick in 1919. Short thereafter, it was used as a way to absorb extra moisture in humid areas, during World War I. By the time World War II came about, it was an indispensable substance used in almost all aspect of the war from keeping the new antibiotic penicillin dry, to maintaining weapons by protecting against moisture.
Applications of Silica Gel Packets
Today silica gel is usually packaged into silica gel packets and used for preserving all sorts of goods: from leather accessories to meat products and electronics. Water, or rather condensed water, tends to either directly ruin a lot of products or promote their decay. For example, water (especially in combination with salt) acts as a catalyst for the chemical process between oxygen and iron (rusting). Silica gels are used as a desiccants and absorb extra water, storing it in their highly crystallized and dense molecules. Silica gel is the major desiccator used as a way to preserve food. This, because it is basically harmless (unless ingested) in both its natural form and chemically modified form, and it does not quickly decompose or react with common environmental chemicals (so a rather stable substance).
Silica Gel: Properties and Hazards
The main chemical component of silica gel is silicon oxide. Its most common use (besides as a silica gel) is for making and firing glass, it is essentially the same thing that grains of sand are made of. In this aspect, silica gel is harmless unless ingested (in which case it could cause chronic or acute illness of unknown character). However, often times, silica gel packets are used in combination with cobalt chloride which serves as an indicator of desiccant pack saturation with water molecules. The unfortunate news is that cobalt chloride can be toxic to many individuals by acting as a a respiratory and skin irritant. The carcinogenic properties of cobalt chloride are also contested with some claiming that it is a dangerous mutagen. However, companies still continue to use it, giving fare warning on the silica gel packets.