Dehydrating Bags – “Salts”
Dehydrating bags (commonly also referred to as “salts”) are used to remove moisture from within a package to preserve the quality of the products inside.
Although often called “dehydrating salts,” none of the desiccants used for packaging protection are actually salts. In fact, the DIN 55473 industry standard specifies that dehydrating bags must not contain any trace of salt (chlorides) to prevent oxidation when in direct contact with metal surfaces. Over the years, desiccants have been likened to salt, likely because silica gel resembles coarse kitchen salt and because salt itself has hygroscopic properties. However, salt is not technically a dehydrating agent, as it adsorbs moisture but does not retain it as effectively as clay or silica gel.
Why Are Salts Not Used in Packaging?
Firstly, dehydrating bags are placed inside packaging in direct contact with goods that need protection, so they must not cause any type of oxidation.
Secondly, silica gel and dehydrating clay have characteristics that common salts do not possess.
Desiccants Are Highly Efficient Materials:
- They can reduce relative humidity to levels below 4%.
- They do not easily release adsorbed moisture.
The primary desiccants used for packaging protection are:
- Calcium Bentonie (also known as Montmorillonite, Salt, Expanded Clay, Active Clay, Desiccant, Bentonite, Dried Clay)
- Silica Gel (often also called Salt, Silica Gel, Silica, Silicon, Drying Gel)
Are Salts Used in Protective Packaging?
The distinction between desiccants (silica gel and clay) and salts is important to avoid misunderstandings in certain situations.
Calcium chloride (which is indeed a salt) finds its natural application in dehydrating bags used to protect containers from the “rain effect.”
In this context, it’s necessary to absorb large amounts of moisture without needing to reach low relative humidity levels (typically aiming to maintain relative humidity around 50% within the container). Thus, the characteristics of calcium chloride make it the ideal desiccant for this purpose.
It is a hygroscopic salt characterized by a high capacity (the amount of water vapor it can remove from the environment) and limited efficiency (the dryness level it creates around itself is about 40% relative humidity).
Desiccant Selection
- Dehydrating Clay: General industrial use.
- Silica Gel: Pharmaceutical industry.
Transport Protection via Container
- Calcium Chloride: Levodry Gel, Container Bag.
