Silica gel:- Features, Applications, Testing and Recharging

Silica gel is an amorphous form of silica (SiO2) which is widely used for the purpose of adsorption of moisture from the environment. 

You can see a packet of silica gel generally on the display board of the new machine. This helps to adsorb the moisture present in the air. In my case, I always carry it in my tools box. This helps to protect my tools from rusting. Also, it is used for electronic components.


  • Chemical Formula:- SiO2
  • Molar Mass:- 60.08 g/mol
  • Porosity:- Around 2.4 nanometers
  • Surface Area:- Around  750–800 m2/g
  • Odor:- Odorless
  • Toxicity:- Non-toxic
  • Reactivity:- Inert
  • Adsorption:- It can adsorb up to 40% of its mass.

Silica gel uses

(What is silica gel used for?)

  • Prevents the rusting of the tools, razor blades, electronic components, etc.
  • Prevents the silverware and the jewelry from tarnishing.
  • It prevents the formation of molds and bacteria onto your leather dress and shoes by absorbing all the moisture from the surrounding environment. 
  • Coffee when comes in contact with the moisture of the atmosphere forms a cluster. So, place a packet of silica gel into the cap of the coffee jar to solve the problem.
  • It can even protect your wet cell phone. For this to work, wipe out the excess water from the cell phone with the help of tissue paper. Then remove the battery from the phone. Finally, place the battery and the cell phone inside the zip-lock bag along with the packet of the silica gel. 
  • The gym bag carries your wet towels and dresses. So, you can put the gel inside the bag to suck the moisture and get rid of the smell of sweat.
  • Defog the windshield of the vehicles by placing few packets of silica on the dashboard.
  • Silica gel for Breather Transformer:-  Silica gel is also applicable in the breather transformer for controlling the moisture and protecting the inner components. It is mostly used for protecting the transformer oil.

Side effects of Silica gel

  • Silica is almost an inert compound. Thus, it hardly takes part in a chemical reaction. So, it is not a dangerous thing to have around.
  • If you consume it, it will adsorb moisture from your body and makes it dry. So, if you happen to swallow it, make sure that you drink plenty of water and visit a doctor.
  • It is indigestible.

Testing of the silica gel?

A few of the simpler methods to check the quality of the gel is as follows.

  • You can observe the packet of gel in the presence of light. Moisture converts silica gel from white to yellow.
  • The other way to check it is by checking its weight


Let the mass of the gel before use = 2 gm

Once it is saturated with water it gains 40% weight. So total mass after saturation                                                        = 2gm + 40% of 2gm

                      = 2gm + 0.8 gm

                     = 2.8 gm

You can measure the weight with the help of a two-digit digital balance.

How to recharge?

Set your micro-oven to 120oC and pre-heat it for about 5 mins. Then place silica gel in the micro-oven and operate it for 1-2 hrs. You can even lower the temperature and extend your time of operation. Then, you will be ready to use it again. 

Recharging the silica gel with the help of a micro-oven takes a long time. So, instead of that, you may even use a stove. For this, take out the outer cover of the silica packet. Then place it in the frying pan. Now turn on the stove and put the flame in the lowest intensity. Now put the frying pan on the stove and heat the silica. Stir the silica from time to time. Also, make sure that you do not overheat the gel. Keep on observing the color change. After a few minutes, the silica gel will be recharged. Now you are ready to reuse it.


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