Silica gel

Silica gel is a classic desiccant for dehumidifying the ambient air inside packaging, for example for medicines and food supplements. It adsorbs moisture (water vapor) and binds it due to its large specific surface area. It is odorless and colorless and resistant to most substances except hydrofluoric acid and strong alkalis.

Silica gel, "Silika Gel" or "Kieselgel" ?
Industry-specific terms.

The English spelling silica gel has become established as a desiccant, even in Germany. Alternatively, the German spelling “Silika Gel” is also used in the German chemical industry, for example. In the pharmaceutical and laboratory sectors in Germany, however, silica gel is also known as “Kieselgel”.

Important to know: It is the same material.

Properties of silica gel


Silica gel is an adsorbent, not to be confused with absorbent. Adsorption refers to the process by which molecules adhere to the surface of a solid without penetrating its structure. This is why Silica Gel retains its hard and perceptibly dry state even when saturated.


Silica gel is hygroscopic, which means that it attracts water vapor. The water molecules are adsorbed by the silanol groups on the silica gel surface from a relative ambient humidity of approx. 10%.

Water absorption capacity

The water absorption capacity of silica gel is strongly influenced by the manufacturing process and is usually between 30 and 40%. When used as a desiccant, it depends on the relative humidity of the environment.


Silica gel can be completely regenerated by heating to 120°C and is then ready for use again.

The process of water absorption and regeneration makes silica gel an efficient desiccant. However, it is important to note that silica gel cannot absorb moisture indefinitely. To maximize effectiveness, the packaging in which the silica gel-filled desiccant product is placed should be sealed airtight. This means that no additional moist air can get in from outside.

Silica gel orange - Silica gel with color change

Silica Gel orange is identical in function to white Silica Gel. However, it was produced with a dye that serves as an indicator to visualize saturation.

When dry, the silica gel is orange in color; when saturated with water vapor, it changes color (color change). The color change can be green, violet or white. We use a silica gel for our desiccant products that turns white.

It is used with transparent containers or in semi-transparent bags or bags with a viewing window. This enables a simple visual inspection to determine the condition and replace the desiccant if necessary.

Difference to molecular sieve

The water absorption capacity of silica gel is higher than that of molecular sieve and increases with increasing relative humidity. However, Silica Gel only begins to adsorb water vapor from a relative humidity of approx. 10%. It can be regenerated at significantly lower temperatures. In terms of price, silica gel offers a clear advantage over molecular sieve.

Especially when it comes to contact with pharmaceutical products, the highest quality and safety in use are essential. At ThoMar, you always get the right desiccant with all the necessary certificates, no matter what you choose.

Humidity regulator / Humidity Control

There are also special types of silica gel-based products known as humidity regulators or humidity control packs. It is used to protect products that require a certain moisture content. The desiccant must not dry out the product and excess moisture must be able to be absorbed. The silica gel is conditioned to the desired value for this purpose.

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