What is Silica Gel and how does it work?
Silica Gel is a glass-like, porous structure of silicon dioxide (SiO2). It adsorbs up to 35% of its own weight. And you read it correctly, that’s adsorb and not absorb. Silica Gel adsorbs moisture with the water molecules adhering to the surface of the Silica Gel granule. Silica Gel is covered in millions of pores that retain this moisture. Pore opening size ranges a magnitude up and down from a billionth of a metre (nanometre). The pores create a huge surface area, which will bind water through surface adsorption and capillary action.
Silica Gel packets provide an economic and effective way of protecting against moisture damage during transit and storage. The sachets are filled with non-indicating beaded silica gel desiccant, available in a variety of sizes.
Silica Gel can be used for protecting electronic equipment, cameras, tools, computers, musical instruments, preservation packaging and all humidity sensitive products.
Silica gel come packaged in Tyvek bags which are made from high density polyethylene fibers, making them extremely tear-resistant. In addition, Tyvek is lightweight, flexible, smooth, low-linting, and is resistant to water, chemical abrasion, and ageing. The Pro-Ex silica gel range is food grade.
Silica Gel desiccants are available in different qualities, which exhibit different absorption characteristics. In general, a particular Silica Gel will have a maximum adsorbance at a particular relative humidity. The adsorbance will fall off at either direction from this point.
Under optimal conditions Silica Gel will adsorb up to 35% of its own weight, but under practical conditions usually much less.
The adsorption ability falls at temperatures above 30-40°C. Although some moisture can be adsorbed at temperatures up to 80°C, the risk of re-evaporation of already adsorbed moisture make silica gel unsuitable for use in an environment where temperatures of above 40°C may occur even temporarily.
NOTE: Silica Gel desiccants are NOT suitable as a shipping desiccant but can be used in packages where the risk of high temperatures is small.
Advantages of Silica Gel
- non-toxic and non-flammable
- adsorbs up to 35% of its weight in moisture.
- if stored correctly can have an almost indefinite shelf life.
- can be reactivated and reused if required.
Silica Gel Applications
- Prevent mould – leather goods, photo albums, certificates, photo frames
- Reduce spoilage and prolong shelf life – dried fruit, herbs, nuts and medication bottles
- Prevent corrosion – camera equipment, tools