How Does Silica Gel Work?

What is silica gel, and why do I find little packets of it in everything I buy? Christian explains it all in this episode.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hi, I'm
Christian Sager. This is brain stuff And today's question is
what is silica gel? And why do I find little
packets of it in so many things? I mean, that's weird, right,
Why would my new boots and my beef jerky be

(00:22):
packed with the same stuff. Silica or more precisely, silicon
dioxide is the same stuff that quartz in sand are
made of. It's a desiccant, meaning it adds orbs and
holds water vapor. And that's ads orbs with an ad
not absorbs. When we say that something ads orbs moisture,

(00:43):
we mean that water molecules adhere to the surface of
the material. Think of the way that sand can seem
to soak up water. The water is really just adhering
to each grain. Basically, silica gel does the same thing.
It's covered in millions of tiny pores that can retain moisture.
It can actually adds orb about forty of its weight

(01:03):
in moisture and can thus reduce the relative humidity in
a closed container down to around So you'll find silica
gel packs and anything that 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, and because silica gel is nearly harmless, you'll

(01:24):
find it preventing spoilage in foods like pepperoni. You still
don't want to eat it, though. If you emptied out
a packet and ate the beads, they would begin adsorbing
moisture from your tongue, gums, and the rest of your mouth.
Your first instinct would probably be to spit it out.
But if you did swallow it, well, okay, probably you'd
be fine. But not all silica gel is the same.

(01:46):
Some has a toxic coating of cobalt chloride. Swallowing this
stuff probably won't kill you, but it might cause nausea, vomiting,
and a few other less than awesome symptoms. And when
it comes to keeping things dry, silica gel works pretty well,
which is why it's so widespread. It's also found in
vitamin containers, industrial air systems, and oddly enough, containers of

(02:08):
cat litter. And this stuff is reusable. You can dry
it out by heating it in an oven at about
three hundred degrees fahrenheit. That's about one fifty degrees celsius,
and people have found all sorts of ways to reuse it.
There might be too many to list. I mean, all right,
I guess I can try. Here. It goes protecting papers
from humidity, drying flowers, preventing rust on tools, preventing condensation

(02:31):
on windows and inside picture frames, preserving art in display cases,
mitigating small spills in luggage, slowing silver tarnishing, stopping seed mold,
and preventing camera lens from fog. Check out the brain
stuff channel on YouTube, and for more on this and
thousands of other topics, visit how stuff works dot com