What is Desiccant?
Desiccants are agents and compounds, such as Silica Gel or Montmorillonite clay. Their primary purpose is to facilitate and maintain low humidity environments by absorbing excessive moisture content present in the air. The most typical applications are storage facilities, transportation, or maintenance facilities of various products and materials. Desiccants also come in handy to keep everything from military munitions to keeping gym shoes dry.
Desiccants can be packaged alongside food items because they are not toxic or harmful. However, consuming them may result in unpleasant health issues such as nausea, vomiting, and headaches. One Desiccant commonly used is Silica Gel, as it works incredibly well for keeping things dry. Apart from metals, Desiccants can also protect paper from humidity, preserve art and display cases, slow silver tarnishing, and do various other things.
What Causes Moisture Damage?
Different possibilities can result in water contamination in a closed package or container, and desiccant has a specific purpose of combating these conditions.
- Presence of water vapour present in the air within a package
- Any moisture contained within the material inside a package
- Moistures on and in the walls of a package
- The penetration of moisture inside a packaging
Where to Start?
Determine the conditions to maximise the product’s integrity, including the type and size of the container used and other actual conditions such as relative humidity and temperature. Take readings of the environment, as it will help select the right type of desiccant. The conditions surrounding the storage and shipment of the product are important factors to monitor. These include the extremes of relative humidity and temperature to which products might get exposed. The duration of the exposure also plays a part.
The most practical combination of measures of relative humidity and temperature will be the dew point. Dew point, by definition, is the temperature limit at which the water vapour in the air exceeds its saturation point, squeezing out excess water forming dew or condensation. The dew point can vary and depends on the quantity of water vapours content present in the air. It is higher with moist air and lowers with dry air. An appropriate desiccant tends to absorb all the water vapour present in the air and reduce the relative humidity to a level where water condensation is impossible.
Packaging Requirements to Take Note
- The total volume of the container’s air space that needs to be desiccated
- What type of material needs to be protected
- Is there any moisture present in the surrounding of the package
- What type of desiccant will be appropriate to use
- The duration of time that requires the protection
- Atmospheric conditions – relative humidity and temperature. It is essential to take note of the environment on where and how the product packaging takes place. Additionally, what will be the conditions during shipment and storage?
Follow a general rule of thumb that is 1.2 units of an adequate desiccant will help protect approximately one cubic foot of container space. One unit of desiccant would be equivalent to 33gms of desiccant clay bag. For example, a container with measurements of 15”x15”x12”. This measurement translates to a total of 1.5625 cubic feet or 2,700 cubic inches. It will require approximately 1.9 units of desiccant that is 1.2 multiplied by 1.5625, to keep the container dry.
However, there is a possibility that not all distributors will carry a 1.9 unit bag of desiccant; therefore, the recommendation is to use a round-up amount, which in this case will be a 2-unit bag. Using more quantity of desiccant than is required is also encouraged in the event of unforeseen circumstances.
Five Common Desiccants
It is one of the naturally occurring absorbents created by controlled drying of a compound known as magnesium aluminium silicate. Montmorillonite clay can successfully regenerate for repetitive use at low temperatures without any swelling or substantial deterioration. It is highly effective and inexpensive when used within normal relative humidity ranges and temperatures.
Silica Gel, represented as a chemical formula of (SIO2 * H2O), is one of the most commonly used desiccants. It is an amorphous form of silica achieved from the combination of sulfuric acid and sodium silicate. It has interconnected pores, creating a large surface area to attract and hold any water or moisture by capillary condensation and absorption. Silica Gel is exceptionally effective below 77ºF or 25ºC; however, it starts losing its absorption capabilities as the temperature rises.
This one is alternatively known as “Synthetic Zeolite” or aluminosilicate. The Molecular Sieve also contains a network of empty absorption cavities and crystalline pores, which provides an internal surface area for absorption of 700 m² to 800 m². It has a uniform structure, which means a Molecular Sieve is better than Activated Clay or Silica Gel as it will not desorb moisture inside the package.
Calcium Oxide (Cao)
Calcium Oxide (CaO) is a recalculated or calcinated lime with a moisture absorption capacity of up to 28.5% by weight. One of its unique features is that it can absorb a higher quantity of water vapour at extremely low relative humidity than other materials.
Calcium Sulfate (CaSO4)
Calcium Sulfate (CaSO4) is also well known by its commercial name is Drierite. It is one of the inexpensive alternates to desiccants available in suitable packaging. The creation of calcium sulfate occurs by dehydration of gypsum in a controlled process. It is a general-purpose desiccant mainly used in laboratories. It is chemically non-disintegrating, stable, non-corrosive, and non-toxic, and it does not release the absorbed moisture or water on exposure to higher temperatures. The lower cost of this desiccant also comes with a low absorption capacity. Calcium sulfate can only absorb up to 10% of its weight in moisture or water.
Uses of Desiccants
Desiccants are ideal for use in low evaporation rates and high humidity levels. Desiccants are also known as dehumidifiers because they absorb excess moisture in the air, keeping the environment dry.
- Goods Transportation
Desiccants that have been commercially developed are often used together in the packaging when shipping products. Temperature changes and moisture-related issues are common problems for products shipped over long distances.
- Desiccants based on activated carbon
Carbon is well known for its ability to extract impurities. One of the most important properties of activated carbon as a desiccant is its ability to eliminate any foul odours in enclosed containers or packaging, such as basements, garages, and storerooms.
- Natural Dehumidifiers
Desiccants are useful in commercial settings, but they are also important for protecting domestic products. For instance, pulses, spices, and other food items can rot if exposed to moisture. Germs will grow, and lumps will form if these items are exposed to moisture. Many people have been using rice and salt as a natural desiccant source to deteriorate food. A small amount of rice or salt in a spice jar will prevent the spice from becoming soaked in moisture for an extended time.
- Preserving Chemicals.
When certain chemicals are exposed to moisture, they will react to form compounds. As a result, it is important to use the proper desiccants when storing chemicals.
Advantages of Desiccants
Desiccants can be used as a protective solution. One of the primary reasons is its wide range of applications. Desiccants can also be used for items other than metals, giving them a broad range of applications. Furthermore, because Desiccants are simply small amounts of silica, they are far less expensive than other methods.
Desiccants, which act as dehumidifiers, can be used if you need a safe, clean, and dry protective packaging solution. When the desiccant has reached its maximum absorption capacity, it must be replaced. Otherwise, a desiccant can become saturated and leak moisture into the package. As a result, rather than preventing corrosion, it may become a source of corrosion.
Commonplace Applications of Desiccants
- Electronics Drying
Desiccants can be used to dry out phones damaged by water instead of a hairdryer. First, remove the device’s memory card, SIM card, and battery and place them in an airtight container filled with as many desiccants as possible. Next, keep the packaging tightly sealed overnight. Desiccants such as Silica Gel or Molecular Sieves are recommended in such cases.
- Basement Storage
Basements are notorious for being the wettest rooms in the house. As a result, if a household has a basement storage area, placing a couple of container desiccants in the storage compartments will protect it from moisture in the air.
There are numerous moisture control products available, so selecting the right desiccant is important. The packaging and container volume will determine the type and quantity of desiccant used. It is critical to consider the amount of moisture needed to be absorbed and the rate at which the process must occur when selecting one of these options. Overall shipping and storage conditions also play a role, with temperature and humidity targets influencing the final decision.
Here is a video about Desiccant Bags.