Science Facts

How Does Silica Gel Work? – Moisture Protection

Silica Gel

Silica gel is a naturally occurring mineral that is purified and processed into either granular or beaded foam. It is most commonly encountered in everyday life as beads in a small paper packet. By placing this in the product, moisture is controlled, mold growth is limited, and spoilage is reduced. Since silica gel can have added chemical indicators and absorbs moisture very well, there are a surprising number of users for those tiny packets.

Silica gels are mostly beneficial in anything that will be affected by excess moisture or condensation. It is very effective in keeping electronic gadgets safe from condensation, which might damage the electronics.

How does silica gel work?

Silica or silicon dioxide is the same stuff that quartz and sand are made of. It’s a desiccant, meaning that it adsorbs and holds water vapor. And they deal with moisture in a pretty interesting way: through adsorption, not absorption. It controls humidity to avoid spoilage or degradation of goods.

  • Absorption is when material permeates or is drawn into a substance like the way plant and animal cells, or the cells in a sponge, soak up water.
  • Adsorption is when a material sticks to the surface of a substance.

Something adsorbs moisture which means water molecules adhere to the surface of the material. Think of the way that sand can seem to soak up water. The water is just adhering to the surface of each grain. Basically, silica gel does the same thing. It’s covered in millions of tiny pores that can retain moisture. It can adsorb about 40% of its weight in moisture. And thus can reduce the relative humidity in a closed container down to about 40 percent.

Silica gel packs in anything would be affected by excess moisture. It’s in with leather products where it can limit the growth of mold. You’ll see it packaged with electronics to reduce condensation. As it’s nearly harmless, it prevents spoilage in foods like pepperoni.

Some of silica gel pack has a toxic coating of cobalt chloride. Swallowing this stuff probably won’t kill you, but it could cause nausea, vomiting, and a few other less than awesome side effects. But, when it comes to keeping things dry, silica gel works pretty well. It’s also found in vitamin bottles, industrial air systems, and cat litter containers. And, this stuff is reusable.

You can dry it out by heating it in an oven at about 300 degrees Fahrenheit. That’s about 150 degrees Celsius. People have found all sorts of ways to reuse it. There might be too many to list:

  • Protecting papers from humidity.
  • Drying flowers.
  • Preventing rust on tools.
  • Preventing condensation on windows and inside picture frames.
  • Preserving art and display cases.
  • Mitigating small spills in luggage.
  • Slowing silver tarnishing.
  • Stopping seed mold.
  • Preventing camera lens fogging.

If the beads inside of the packet have changed color, that means they’re oversaturated. So they’ll usually turn from white to yellow, from blue to pink, or from orange to dark green.


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