Container rain refers to moisture condensation inside a shipping container that occurs when warm, humid air cools down and forms water droplets on the container’s interior surfaces. As temperatures fluctuate during transit, this condensation can drip onto goods, leading to mould growth, rust, corrosion, and packaging damage. When the container is exposed to temperatures below the dew point, the moisture from the ambient air will condensate, which is visible at the ceiling and walls of the container. This water will then drip onto the cargo.
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Container rain is a major concern in international shipping, particularly for long-distance freight, ocean shipments, and containers crossing multiple climate zones. Without proper moisture control, it can lead to significant financial losses due to damaged products.

Container rain is caused by temperature fluctuations and humidity inside the container. Here’s a breakdown of the process:
1. High Humidity Trapped Inside the Container
Shipping containers are airtight once sealed, meaning any moisture present at the time of loading remains inside.
Cargo with a high moisture content (such as wood, textiles, paper, and food) naturally releases moisture into the air.
Even seemingly dry goods can contribute to humidity buildup.
2. Temperature Drops During Transit
As the container moves through different climates or night-time temperature drops, the air inside cools down.
Cooler air cannot hold as much moisture as warm air, leading to condensation.
3. Condensation Forms on the Coldest Surfaces
Water vapor in the air turns into droplets when it touches the cold interior walls and ceiling of the container.
This effect is especially strong in metal shipping containers, as metal conducts heat and cools quickly.
4. Water Drips onto Cargo (Container Rain)
Over time, moisture accumulates on the container ceiling and walls.
It then drips onto cargo, much like rain inside the container—hence the term “container rain.”
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Airflow Access = Moisture Access
Desiccants need
unobstructed access to ambient air
to pull moisture from it. If a desiccant is buried under cargo, crammed into a tight corner, or sealed away from airflow, it will be far less effective.
Proximity to Moisture Sources
Placing desiccants
near walls
,
under container ceilings
, or near
cargo that emits moisture
(like wood, textiles, or food) allows them to absorb humidity
before it condenses
.
Sufficient Open Volume Around Each Unit
A
hanging desiccant bag
works best when it has at least
10–30 cm of open space around it
, allowing air to circulate freely across the bag surface.

Best Practices for Desiccant Spacing and Placement
​

Avoid These Mistakes
Don’t
stack or bunch
desiccants together – it reduces surface area exposure.
Avoid
placing them directly on the floor
unless designed for it (e.g. flat desiccant mats).
Don’t ​place them inside ​shrink wrap – they can’t absorb moisture from sealed air.
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Why You Should Avoid It
Blocked Airflow = Reduced Effectiveness
Desiccants work by
pulling moisture from the surrounding air
. If they’re wrapped in plastic or tightly sealed under stretch film,
air can’t reach them
, and they can’t absorb humidity effectively.
Traps Moisture Inside
If any moisture is already inside the pallet area when shrink-wrapped, the desiccant can’t
ventilate or remove
it – it’s essentially sealed in with the cargo.
Wasted Desiccant
Even a high-performing desiccant like calcium chloride won’t help if it’s
isolated from open air
. You’ll use ​the product without getting full protection.
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Better Practice
Hang or attach desiccants
along the container walls or from lashing rings.
Ensure
10–30 cm of open space
around each unit for proper airflow.
If placing near pallets, position the desiccant
outside the shrink wrap
or
between pallets
with clear air exposure.
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Final Tip: Think of desiccants like air filters
The more air they’re exposed to, the more moisture they can absorb. For best performance, always consider
airflow
,
space
, and
strategic placement
— not just quantity.

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The Absorbag 1.5kg Desiccant is easy to use and designed to occupy minimal container space while providing maximum functionality. With high performance and a long-lasting absorption rate, the Absorbag 1.5kg offers efficient protection for long shipments. The absorbed moisture gradually dissolves into a brine, which is captured in the lower part of the Absorbag. Once captured, the moisture will not re-evaporate back into the air.

To install the Absorbag 1.5kg, attach it to the container lashing ring using the provided Absorhook. It can be used for any type of carton, ensuring at least 10 cm space between the cargo and the Absorbag. For cargo loaded higher than 1.5 metres, install the Absorbag above the cargo. The absorbed moisture is safely contained as brine in the bottom of the bag, preventing leaks.
[See the Absorbag Installation Guide for details.]

The Absorbag 1.5kg has an absorption capacity of up to 150% of its weight.

The number of Absorbag 1.5kg units depends on container size, shipping duration, cargo moisture content, and length of voyage. As a general guide:
4 to 8 units for a 20ft container, and
8 to 14 units for a 40ft container.

Protection Experts Australia can provide tailored calculations for your cargo and shipping conditions.

The Absorbag 1.5kg is made only from PE/PP plastics and salt, which are non-toxic and recyclable. It is a single-use product and can be disposed of with regular waste. For full instructions, refer to the Absorbag Installation & Disposal Guide.

No. The brine is simply calcium chloride, a very salty solution. It is not dangerous, but avoid getting it in your eyes. If contact occurs, rinse thoroughly with water. Always wash hands after handling.

Absorgel 1kg is a container desiccant used to protect goods from moisture damage during shipping and storage. Absorgel 1kg prevents issues like container rain, mould growth, rust, and packaging degradation by absorbing excess humidity inside sealed environments.

Absorgel 1kg is part of a sustainably produced moisture protection range. The product’s carbon emissions – across manufacturing, transport, and disposal – are measured and offset through verified carbon credits, making Absorgel 1kg a certified carbon neutral desiccant.

Each Absorgel 1kg unit can absorb up to 300% to 350% of its weight in moisture, making Absorgel 1kg highly effective for long-duration shipments or goods traveling through high-humidity climates.