What is Silica gel?

Know your Silica gel

Damage Prevention

What is Silica gel?

What is Silica gel?

Sometimes found in food packaging, you’ll find a small, white packet with “silica gel” written on it. 

Have you ever wondered what this silica gel is and why we find it everywhere? 

First, let’s get to know what silica gel is.

Silica gel is an amorphous form of silicon dioxide, which means that its atoms have an irregular framework. In the traditional frame of silicon gel, oxygen and silicon atoms are placed at a distance, which measured in the nanometer-scale, which creates pores in the structure. The second quality of silica gel is that it is an acceptable form.

If these voids or pores filled with gas or vaccine, the silica gel is called silica xerogel.

Silica gel is usually the component that we find in those little packets in granular form. Some of them contain some indicators which can change colour after absorbing water.

For silica gel, this is one of the essential properties, and we’ll see why in the next few lines. 


What are the properties of Silica Gel?

Silica gel has a high surface area of around 800 m2/g. The high surface area allows the silica gel to absorb water, making it useful as a desiccant or drying agent. 

Silica gel mostly used for absorbing moisture, which is appropriate for protecting different goods again corrosion, contamination, spoilage, and growth of mold. 

Silicon dioxide is the primary component of silica gel, which treated in granular or beaded form. 

This silica gel is available in loose bulk or packets for different humidity detection and control purposes.

There are different kinds of silica gel varied based on size, color, and kind. 

The three widely available colors are white, blue, and orange silica gel. These indicating silica gels are processed with indicators to determine the moisture saturation of a product and its need for saturation.


Difference Between White, Orange, and Blue Silica Gel:

White Silica Gel:

It is a non-indicating silica gel. That means that even after absorbing the moisture, it does not change color. 

You’ll see this silica gel mostly in the packets found in backpacks, bottles, etc. If you open that bag, you’ll see white silica gel in granular form.


Orange Silica Gel:

This silica gel has a component for indication called methyl violet. It is capable of changing color from orange to green or orange to colorless. 

Again, the orange silica gel is also toxic, even though it has some medicinal merits.

Like blue silica gel, it can reactivate by heating it. When it turns back to orange again, it can be reused.


Blue Silica Gel:

This gel has cobalt chloride, which will allow the blue silica gel to change its color to pink when it’s reached its maximum absorption value.

If the blue silica gel turns pink, it can be reactivated using the application of heat. 

This silica gel is not used around food products since cobalt chloride is poisonous.


Applications of Silica Gel:


Moisture encourages the growth of mold and spoilage in some items. The condensation may also damage goods in packaging that are highly sensitive to water contact like electronics and might speed up the decomposition of elements in vitamin pills.

Silica gel is used in these places to absorb the moisture and preserve these items longer.

Silicon is also used to maintain the relative humidity inside a high-frequency radio or satellite transmission system as low as possible. 

Silica gel used to dry the air in industrial compressed air systems as well. Air from the compressor discharge flows through the bed of silica gel beads, and the silica absorbs moisture from the air to prevent damage due to the incorporation of humidity in the process.

It is also used as a preservative to control relative humidity in places like libraries and museums.

Other applications include diagnostic test strips, inhalation devices, syringes, drug test kits, etc.


Food Additive

Silica gel, also known as silica aerogel or hydrated silica, is verified by the FDA as GRAS (Generally Recognised As Safe).

That means it can add to different food products without needing approval. 

In the USA, around 2% of silica is allowed to be added to food whereas in Europe, the permitted level is 5%.

The uses are anticaking agents, defoaming agents, stabilizers, adsorbent, carrier, conditioning agent, etc.


Humidity Indicators

As stated above, different colored silica gels can be used as a humidity indicator.

For making these indicators, silica gel is incorporated with different indicators like cobalt chloride or methyl violet.

These agents change colors to indicate the anhydrous state to a hydrated state.


Hazards of Silica Gel:

Silica gel is non-toxic, non-flammable, non-reactive, and stable to use. 

It might react to elements like hydrogen fluoride, fluorine, oxygen difluoride, oxygen difluoride, strong acids, strong bases, as well as different oxidizers.

Silica gel can be irritating to the respiratory tract and can also irritate the digestive tract. 

Dust from the beads can irritate eyes and skin. So, it would be best if you took the necessary precautions while handling the silica gel.

The use of silica gel will increase the shelf life of various products. These products include medicines, medical components, electronics components, food products, and day to day essentials.

Even with the hazards listed above, silica gel is safe to use in products that come in direct contact with us. That is why you can see it packages of food products.

If you can adequately use it the right way, silica gel makes for an excellent humidity indicator, and you can use it again and again by reactivating it with the application of heat. 

You can find a range of different products that use silica gel as a desiccant and as an indicator.