A shipping container can leave port completely dry and arrive with mouldy cartons, rusted components, damaged labels, or spoiled products. In many cases, the issue isn’t poor handling; it’s moisture trapped inside the container.
During transit, fluctuating temperatures can cause condensation to form on the container’s ceiling and walls. This is often called container rain, and it can damage cargo worth thousands of dollars.
That’s why many exporters increasingly rely on shipping container desiccant bags to control humidity throughout the journey.
This guide explains where container moisture comes from, how container desiccants work, how many desiccant bags per container are needed, and how to choose the right moisture-control solution for your cargo.
Click the section to read:
What Damage Can Moisture Cause During Shipping?
Where Does Moisture in Shipping Containers Come From?
How Container Desiccant Bags Work
Types of Desiccants Used in Shipping
How Much Moisture Can Pak-Dry Absorb?
What Happens if You Don’t Use Container Desiccants?
Which Industries Commonly Use Container Desiccants?
How Many Desiccants Should Be Used?
How to Install Shipping Container Desiccant Bags
How to Select the Right Desiccant for Different Cargoes
Before You Seal the Container: A Moisture-Control Checklist
Why Australian Exporters Choose X-Pak
Protect Your Cargo from Moisture Damage
Order Pak-Dry or Book a Free Site Visit
Frequently Asked Questions About Container Desiccants
What Damage Can Moisture Cause During Shipping?
Moisture can cause significant damage to products during storage and transport.
Common moisture-related risks include:
- Rust and corrosion on metal products
- Mould growth on textiles and leather goods
- Warping and staining of timber
- Packaging failure and label damage
- Spoilage in food and beverage shipments
- Damage to electronics and sensitive components
Even a small amount of condensation can result in rejected export shipments, insurance claims, and costly delays.
Where Does Moisture in Shipping Containers Come From?
Many shippers assume that moisture enters only from outside the container. In reality, much of the moisture risk can already be present before the doors are sealed.
Moisture can originate from:
- Humid ambient air trapped inside the container during loading
- Residual moisture in pallets, timber, or packaging
- Damp cargo materials
- Temperature changes throughout transit
- Wet container floors or previous condensation
As temperatures fluctuate, warm air inside the container can cool to the dew point, causing condensation to form on the container’s ceilings and walls.
This is commonly known as container rain.
How Container Desiccant Bags Work
A moisture-absorber shipping container solution helps reduce the relative humidity inside a sealed shipping container by absorbing water vapour from the air. This helps reduce the risk of condensation forming on the container walls, ceiling, packaging and cargo surfaces.
While barrier films and container liners can help separate cargo from external moisture, desiccants work inside the container itself. They continue to capture moisture released by the cargo, timber pallets, cartons, packaging, and humid air throughout the journey.
This is especially important during long export shipments, where changing temperatures can cause moisture in the air to condense into water droplets, known as container rain.
X-Pak’s Pak-Dry container desiccant bags use high-performance calcium chloride technology to absorb moisture inside the container. Each 500g bag can absorb up to 1.5 litres of water, helping protect cargo from moisture-related issues and consequent damage.
As Pak-Dry absorbs moisture, the liquid forms a gel inside the bag. Its one-way membrane design helps prevent leakage during transit.
When installed correctly and used in the right quantity for the shipment, these container dehumidifier bags provide continuous moisture control across long-haul cargo journeys.
For additional guidance, see our article on how to use desiccants in logistics and shipping
Types of Desiccants Used in Shipping
Several types of desiccants are available for shipping applications. These include:
Calcium Chloride Desiccants
Calcium chloride desiccants are often the preferred choice for shipping containers and export freight because of their high moisture absorption capacity.
X-Pak’s Pak-Dry calcium chloride bags can absorb up to 300% of their own weight in water. This makes them highly effective for preventing condensation, mould, corrosion, and container rain during long-haul ocean voyages. Their ability to perform in high-humidity environments makes them ideal for protecting moisture-sensitive cargo throughout transit.
Silica Gel
Silica gel is commonly used inside product packaging, cartons, and sealed containers where lower-level moisture control is required.
It can be useful for protecting individual products or components, but its absorption capacity is much lower than that of calcium chloride. For this reason, silica gel is usually less suitable for controlling humidity across an entire shipping container during extended export shipments.
Clay Desiccants
Clay desiccants are an economical moisture-control option often used for short-term storage and domestic transportation.
Made from naturally occurring minerals, they can provide basic humidity protection but have a lower absorption capacity than both silica gel and calcium chloride desiccants. While suitable for some storage applications, they are usually less effective for long-duration export shipments exposed to fluctuating temperatures and high humidity.
Silica Gel or Calcium Chloride: Which Is Better for Shipping?
When comparing silica gel vs calcium chloride, the right option depends on the level of moisture protection required.
Silica gel is commonly used inside product packaging, cartons, and small sealed spaces, where it helps protect products from minor moisture exposure. However, its moisture absorption capacity is relatively limited, making it less suitable for protecting an entire shipping container during long ocean voyages.
A calcium chloride desiccant is designed for larger-scale moisture control. It actively absorbs water vapour from the air in the container and can absorb up to 300% of its own weight in moisture. This makes it particularly effective for preventing container rain, mould growth, corrosion, and packaging damage during export shipments.
For full-container protection, calcium chloride-based solutions such as Pak-Dry generally outperform silica gel, especially on long-haul and high-humidity routes.
Learn more about the advantages in our guide: Benefits of Calcium Chloride Dehumidifier Bags
How Much Moisture Can Pak-Dry Absorb?
Pak-Dry is designed for high-capacity moisture absorption in shipping containers.
Each bag is activated with premium calcium chloride desiccant technology and can absorb up to 300% of its own weight in water. A 500g bag can capture approximately 1.5 litres of moisture during transit.
As moisture is absorbed, Pak-Dry forms a gel inside the bag. Its one-way membrane design helps reduce the risk of leakage and cargo contamination during transit.
Because of its higher absorption capacity, fewer shipping container desiccant bags are often required than standard desiccant products, helping exporters achieve reliable protection while reducing overall usage.
What Happens if You Don’t Use Container Desiccants?
Without a suitable desiccant for export shipments, moisture can quickly become a costly problem.
Uncontrolled humidity can lead to:
- Container rain and visible condensation
- Mould and mildew growth
- Corrosion and rust
- Product spoilage or quality concerns
- Damaged packaging and labels
- Rejected shipments or customer complaints
For Australian exporters, the real cost extends beyond the damaged cargo. It’s also the time, labour and customer trust that gets affected when goods arrive in poor condition.
Many of these issues are preventable with properly installed shipping container desiccant bags.
Related read: What Shipping Issues Can Container Desiccant Packs Help Solve?
Which Industries Commonly Use Container Desiccants?
Container desiccants are widely used across industries where moisture damage can impact product quality or compliance.
For Australian exporters, this is especially relevant across food and beverage, grain, timber, wool, cotton, leather goods, machinery, packaged agricultural products, and manufactured components. These goods often travel long distances through changing climates, from humid Australian ports to cooler ocean routes and overseas destinations.
Electronics
Electronics and components are highly sensitive to moisture and condensation. Container desiccants help prevent corrosion, short circuits, and damage to sensitive circuitry during storage and transit.
Pharmaceuticals
Many pharmaceutical products require stable environmental conditions to maintain their quality and effectiveness. Moisture control helps protect product integrity and supports compliance throughout the supply chain.
Textiles and Leather
Fabrics, garments, and leather goods can absorb moisture during transport, leading to mould, mildew, unpleasant odours, and product damage. Desiccants help keep humidity levels under control throughout the journey.
Timber and Wood Products
Timber naturally absorbs and releases moisture as temperatures change. Using desiccants helps minimise the risk of warping, staining, cracking, and mould growth during export shipments.
Metal Components and Machinery
Metal products are vulnerable to rust, oxidation, and corrosion when exposed to condensation. Container desiccants help create a drier environment, reducing the likelihood of surface damage and deterioration.
Food and Beverage
Excess moisture can damage packaging, labels, and food products during transit. Desiccants help maintain product quality by reducing humidity and preventing moisture-related spoilage issues.
For industry-specific advice, read our article on Container Desiccants for the Food and Beverage Industry
How Many Desiccants Should Be Used?
One of the most common questions exporters ask is: how many desiccant bags are required per container?
The answer depends on the shipment, route, climate and cargo type. However, one of the key advantages of high-performance calcium chloride desiccants like Pak-Dry is that they provide stronger moisture protection using fewer bags than many standard desiccants.
As a general guide:
| Container Size | Recommended Pak-Dry Quantity |
|---|---|
| 20ft Container | 4 x 1kg bags |
| 40ft Container | 8–12 x 1kg bags |
A typical 20ft container often requires four 1kg Pak-Dry bags, while many conventional desiccants may require up to eight bags for the same application.
This higher absorption capacity improves moisture protection while reducing material usage, simplifying installation and lowering the overall cost per shipment.
The exact quantity will depend on the conditions of your shipment. Longer routes, humid climates, moisture-sensitive cargo, absorbent packaging, timber pallets and extended storage periods may all increase the amount of desiccant required.
How to Install Shipping Container Desiccant Bags
For maximum performance, shipping container desiccant bags should be hung from the lashing lugs located along the upper side walls of the container. This position allows the bags to remain exposed to circulating air, helping them absorb moisture more effectively throughout the shipment. Distribute the bags evenly along both sides of the container rather than placing them all in one location. Good airflow is essential for consistent humidity control and preventing container rain.
For best results:
- Hang bags from lashing points along the upper side walls.
- Space bags evenly throughout the container.
- Ensure airflow around each bag.
- Keep bags clear of pallets and cargo stacks.
- Avoid covering or compressing the bags.
To make installation safer and more efficient, X-Pak also offers the Hanger Tool for Pak-Dry Desiccant. This specialised applicator allows operators to place Pak-Dry bags from ground level, reducing the need for ladders, climbing on cargo or reaching awkward lashing points. It helps speed up installation while supporting safer work practices during container preparation.
Avoid burying desiccant bags beneath pallets, squeezing them between cartons, or covering them with cargo. When airflow is restricted, the desiccant cannot absorb moisture efficiently.
Correct placement helps maximise moisture absorption and improve humidity control throughout the container, protecting cargo from condensation, mould, corrosion, packaging damage and other moisture-related issues during transit.
How to Select the Right Desiccant for Different Cargo
Choosing the right container desiccant pack depends on the products being shipped.
| Cargo Type | Recommended Solution |
|---|---|
| Electronics | High-capacity calcium chloride desiccant |
| Pharmaceuticals | Long-duration moisture protection |
| Timber | Increased desiccant quantities |
| Metals | High-absorption desiccants to prevent corrosion |
| Food & Beverage | Food-safe moisture control solutions |
| Textiles & Leather | Continuous humidity management |
For most export applications, a calcium chloride desiccant such as Pak-Dry provides the best combination of absorption capacity, reliability, and long-haul performance.
Before You Seal the Container: A Moisture-Control Checklist
Choosing the right container desiccant pack depends on the cargo, route, transit time, and moisture risk. Before sealing any moisture-sensitive load, run through this checklist.
Step 1: Identify Moisture-Sensitive Cargo
Flag electronics, pharmaceuticals, textiles, leather, timber, metal, and food and beverage loads early.
Step 2: Confirm Transit Days and Route
Longer voyages and humid climates need more desiccant, not the same amount working harder.
Step 3: Calculate the Right Quantity
Start with 4 x 1kg Pak-Dry bags per 20ft container or 8–12 x 1kg bags per 40ft container, then adjust for transit time, climate, cargo sensitivity and packaging type.
Step 4: Position Bags for Airflow
Hang desiccant bags on the lashing lugs along the upper side walls of the container. Spread them evenly, with nothing blocking the bag’s face.
Step 5: Keep Bags Clear of the Load
Don’t bury bags under pallets or wedge them between tightly packed boxes.
Step 6: Pair Desiccant with Good Packing
Combine moisture control, sound load restraint, and packaging for damage-free freight.
Step 7: Plan Disposal at Destination
Once the shipment arrives, remove used desiccant bags and follow the product handling instructions and local disposal requirements at the destination.
Why Australian Exporters Choose X-Pak
As a leading container desiccant supplier in Australia, X-Pak supports exporters, freight operators, warehouses, and manufacturers with proven moisture-control solutions.
The Pak-Dry range offers:
- High-capacity calcium chloride desiccant technology
- One-way membrane design to help reduce leakage risk
- Moisture absorption of up to 300% of the bag’s own weight
- Fewer bags are required in some shipments compared with lower-capacity alternatives
- Australia-wide supply and support
- Guidance on container size, cargo type, route conditions, and recommended quantities
Browse our full range of X-Pak Global’s container desiccants to meet your needs.
Protect Your Cargo from Moisture Damage
Moisture is one of the most common causes of shipping damage, but it is also one of the easiest risks to manage.
By using the right shipping container desiccant bags, installing them correctly, and using the right quantity for your shipment, you can significantly reduce the risk of container rain, mould, corrosion, and product loss.
Whether you’re shipping electronics, food products, timber, machinery, or pharmaceuticals, a high-performance calcium chloride desiccant such as Pak-Dry provides reliable protection throughout the journey.
Order Pak-Dry or Book a Free Site Visit
For full-container protection on long-haul export journeys, high-capacity calcium chloride desiccants such as Pak-Dry are generally a stronger option than silica gel or clay desiccants, especially in humid conditions or on routes with changing temperatures.
If you are shipping moisture-sensitive goods or storing products long-term, contact the X-Pak team to calculate the right amount of Pak-Dry for your shipment. Order Pak-Dry directly or call 1300 551 281 to book a free site visit.
Frequently Asked Questions About Container Desiccants
How many desiccant bags should I use per container?
The quantity depends on the container size, cargo type, transit duration, and environmental conditions. As a general guide, a 20ft container typically requires 4–6kg of desiccant, while a 40ft container may require 8–12kg. High-moisture cargoes and longer voyages may need additional protection.
Where should shipping container desiccant bags be installed?
Desiccant bags should be hung from the lashing points along the upper side walls of the container. This allows air to circulate freely around the bags and maximises moisture absorption. Avoid placing bags beneath pallets or tightly packed cargo.
How long do container dehumidifier bags last?
Most container dehumidifier bags are designed to remain effective throughout a standard export journey. Pak-Dry is suitable for voyages lasting between 30 and 90 days, depending on environmental conditions and moisture levels inside the container.
Know more about the Benefits of Calcium Chloride Dehumidifier Bags
Are calcium chloride desiccants safe to use?
Yes. Calcium chloride desiccants are widely used across the shipping industry. Pak-Dry converts absorbed moisture into a stable gel, reducing the risk of leakage and making handling and disposal straightforward after use.
Is a container desiccant pack reusable?
High-performance container desiccant packs are designed for single-use applications. Once the bag’s moisture absorption capacity has been reached, it should be replaced.
