Functions of Shipping Container Desiccants

Functions of Shipping Container Desiccants
Published On:September 10, 2021 Revised On:December 28, 2023

Container transportation has evolved into one of the foremost methods for international shipping. Typically, shipping containers are loaded in proximity to the ocean, where the air carries a higher concentration of moisture. Within the confines of the container, which constitutes a relatively enclosed environment, this moisture becomes trapped. As the air settles within the container, it undergoes condensation in colder sections. Subsequently, when the temperature increases, the accumulated moisture ascends within the container before ultimately descending, a phenomenon commonly referred to as “container rain.”

Container rain can significantly foster the proliferation of mould and mildew, posing a threat to the integrity of transported goods. When moisture and fungal infestation take hold and irreparably damage the cargo, it necessitates discarding the entire shipment, ultimately leading to additional transport to fulfil the customer’s order.

When time sensitivity is a concern, expediting the transport via short sea freight becomes expensive. Beyond the substantial economic losses incurred and the unfortunate waste of precious natural resources, cargo damage can cast doubt upon the reputation and credibility of the manufacturer or retailer involved.

The Role of Desiccants

Shipping container desiccants are moisture-absorbing agents designed to combat the moisture-related challenges plaguing shipping containers during transit. Their role is to maintain a dry and stable environment. By adsorbing excess moisture, desiccants play a pivotal role in preventing condensation, inhibiting mould and mildew growth, and thwarting the corrosive effects of humidity. Essentially, they act as sentinels of cargo quality, ensuring that moisture-related issues do not compromise the goods.

Shipping Container desiccants can also absorb moisture up to 280% of their dry weight, unlike other desiccants such as silica gel and activated clay, which only have an absorption rate of 25-30%. Moreover, its Tyvek leak-proof packaging materials allow water vapour to be absorbed and transformed into a thick gel-like structure, eliminating the potential for liquid spillage.

Functions of Shipping Container Desiccants

Shipping container desiccants play a crucial role in maintaining the quality and integrity of cargo during transit by effectively controlling moisture and mitigating its damaging effects. Their multifaceted functions encompass moisture absorption, mold and mildew prevention, corrosion control, preservation of product quality, and adherence to regulatory standards.

By effectively fulfilling these functions, desiccants contribute to the reliability and success of the global supply chain, ensuring that goods reach their destinations in optimal condition. Here, we explore the various functions of shipping container desiccants in detail:

Moisture Absorption

Condensation occurs when warm, moist air meets cooler surfaces within the container, leading to the formation of water droplets. Shipping container desiccants actively absorb excess moisture from the air, reducing the risk of condensation on the cargo or container walls. This prevention of condensation helps safeguard cargo from moisture-related damage, such as rust, mold, or packaging deterioration.

High humidity levels within shipping containers can pose a significant threat to cargo. Desiccants maintain the relative humidity (RH) at safe levels by continuously absorbing moisture. By doing so, they create a dry environment that safeguards goods from the harmful effects of humidity, including spoilage, degradation, and the proliferation of microorganisms.

Mold and Mildew Prevention

Shipping containers are susceptible to mold and mildew growth when moisture levels are not controlled. Mold and mildew not only compromise the aesthetic appeal of goods but can also lead to health hazards and product degradation. Desiccants help prevent the proliferation of mold and mildew by reducing moisture to levels that are inhospitable to these microorganisms.

Corrosion Control

Metal goods are particularly vulnerable to corrosion when exposed to moisture. Shipping container desiccants are instrumental in controlling humidity levels, thereby minimizing the risk of corrosion on metal surfaces. By preventing the formation of rust and oxidation, desiccants help preserve the structural integrity and functional quality of metal products.

Preservation of Product Quality

Many types of cargo, including electronics, pharmaceuticals, and food products, require strict environmental controls to maintain their quality and safety standards. Shipping container desiccants aid in preserving the product quality by ensuring that the cargo remains in optimal condition throughout the transit. By controlling moisture-related issues, desiccants help prevent costly product spoilage or rejection due to compromised quality.

Regulatory Compliance

International regulations and quality standards often require cargo to be transported under specific environmental conditions. Shipping container desiccants assist in complying with these regulations by helping to maintain the prescribed moisture levels. Compliance not only ensures the safety and quality of goods but also avoids potential legal issues or delays in customs clearance.

Types of Container Desiccants

Shipping container desiccants are available in a wide variety, providing versatile protection against moisture and humidity damage during transit. They come in bags and contain a non-toxic clay desiccant mixed with a trace of calcium chloride, making them an excellent choice for transporting items such as coffee beans, canned foods, flour, rice, and many others. Stream Peak offers four types of shipping container desiccants to prevent damage to transport goods and significant economic losses.

Humi Dryer Bag

The Humi Dryer Bag is a container desiccant bag containing a toxic-free, natural clay desiccant infused with a bit of calcium chloride. It has a high vigorous absorption quality over a wide temperature range. The Humi Dryer Bag retains moisture and maintains low humidity levels, absorbing up to 80% of its weight in shipping containers. It absorbs and holds moisture inside the bag as a thick gel that will not turn into water vapour even in high-temperature environments during transit, reducing the risk of potential moisture damage to shipping goods.

Humi Dryer Pole

The Humi Dryer Pole is a container pole desiccant manufactured from polymer gelling agent and calcium chloride designed to prevent condensation on the walls and roof of the container by decreasing the dew point and maintaining a relatively low humidity level. It can be secured either by directly hooking it to the container’s wall ring or simply placing it on the container floor.

It is specially designed to fit in-between the grooves of the shipping container walls due to its pole composition, maximising shipping space while protecting cargo from water vapour by allowing moisture to enter the desiccant, where it quickly takes a gel-like structure. Also, its protective packaging inhibits condensation and leakage from temperature changes in the shipping container.

Humi Dryer Strip/Strip Plus

Shipping Container DesiccantsThe Humi Dryer Strip is a non-toxic, natural clay desiccant mixed with a small amount of calcium chloride that works as a dehumidifier and moisture absorber inside the container or packaging. Capable of absorbing water vapour up to 80% of its weight, the Humi Dryer Strip efficiently removes moisture and lowers humidity levels in the shipping container to ensure a dry surrounding environment, protecting goods from potential moisture and humidity damage during transit and storage. The Humi Dryer Strip can either be fixed by attaching it with a hook to hang it or simply placing it in the container.

The Humi Dryer Strip is also in an advanced version – the Humi Dryer Strip Plus. The Humi Dryer Strip Plus is a specially formulated desiccant made from a calcium chloride polymer gelling agent. It is designed to inhibit condensation on the container walls and roof by lowering the dew point and reducing the humidity level inside shipping or storage containers, protecting cargo from moisture damage while shipping.

Instead of a moisture absorption capacity of 80% like the Humi Dryer Strip, The Humi Dryer Strip Plus can absorb water vapours up to 280% of its weight, a considerable amount of moisture. The Strip Plus allows moisture to enter the desiccant, which takes a gel-like form, preventing container rain and assuring a dry container environment for shipping goods.

Selecting the Right Shipping Container Desiccant

Choosing the appropriate shipping container desiccant is a critical step in ensuring effective moisture control during cargo transit. The selection process requires a thoughtful consideration of various factors to match the desiccant’s capabilities with the specific requirements of the shipment. Here, we explore the key considerations and steps involved in selecting the right shipping container desiccant.

  1. Cargo Type and Sensitivity: Different types of cargo have varying moisture sensitivity levels. For instance, electronics, pharmaceuticals, and food products are highly sensitive to moisture and require stringent moisture control. Conversely, less sensitive cargo like machinery or non-perishable goods may have lower moisture-related risks. Understanding the moisture sensitivity of the cargo is crucial in determining the desiccant’s capacity and effectiveness needed for protection.
  2. Container Size and Volume: The size and volume of the shipping container directly impact the amount of moisture that can accumulate inside. Larger containers have more air space, which can accommodate more moisture. Smaller containers, on the other hand, may require smaller, strategically placed desiccants. Calculating the container’s internal dimensions and volume is essential for determining the desiccant quantity.
  3. Shipping Duration: The duration of the shipping journey can vary greatly, from a few days to several weeks or even months. Longer transit times increase the likelihood of moisture-related issues. It’s vital to select desiccants with the capacity to maintain moisture control throughout the entire journey. This may involve choosing desiccants with higher moisture-absorbing capabilities.
  4. Environmental Conditions: The climate and environmental conditions of both the origin and destination locations can significantly affect moisture levels within a shipping container. Consider factors like temperature, humidity, and seasonal variations. Desiccant selection should account for the expected environmental conditions during transit to ensure optimal performance.


Desiccants, with their ability to prevent condensation, protect against humidity, thwart mold and mildew, control corrosion, and preserve product quality, act as sentinels of cargo quality. By understanding the functions of shipping container desiccants, cargo owners and logistics professionals can enhance the safety, reliability, and reputation of their shipping operations. These moisture-absorbing agents ensure that goods reach their destinations in pristine condition.

Stream Peak is a leading manufacturer of container desiccants with ISO 9001 and 14001 certifications. Our desiccants made in Singapore undergo rigorous daily quality assurance checks in our in-house laboratory. Contact us today to learn more about our shipping container desiccants.