Container rain – what is it and what to do against it

strapa-pack container rain

Container rain – warm, humid air can cause serious damage to your cargo. We’ll tell you what to do against it!

Surprising data: about 10% of the containerised goods end up as waste because moisture and humidity damage the cargo. This is a gigantic amount of waste, which not only means large economic losses, but also has a negative impact on the environment. What causes container rain? And a more pressing question if we think of our customers: How do we stop it from happening? In this article, we will try to answer these questions and give some practical advice on how to prevent such disaster.

It is very important to protect against moisture inside the container.

It goes without saying that it’s very expensive in the long run to say goodbye to 10% of your consignment.

If it’s a single shipment, it may not be the end of the world, but if we’re looking at a whole year – or a decade – then we’re talking about a massive financial loss. If we could sell this discarded 10%, it would greatly increase our profits. If the products have become completely damaged by moisture and fungus, you must discard everything and deliver the goods to the customer again. In addition, if it is an urgent shipment, you may even have to choose the much more expensive air transport rather than sea transport. In addition to economic losses and excess waste, cargo damage can often result in a loss of revenue and, for almost all segments and products, could jeopardise the credibility of manufacturers or retailers, thereby undermining confidence towards them.

What causes container rain?

Container rain is caused by a change in temperature, which may occur when vessels pass through different climate zones. Let us look at a simple example: the container is loaded in Hong Kong, where, thanks to the tropical climate, the air is known to be warm and wet. If the cargo then ends up in the cold Scandinavia and the container is not sufficiently protected from moisture, damage to your cargo can be guaranteed.

When vessels cross the Suez Canal between South Asia and Europe, the temperature of the container can reach up to 80 degrees Celsius! Inside the container, the warm, humid air condenses, which can have negative consequences. Like dewdrops forming on a cold soda can on a hot summer day, condensation begins to form on the surface of the cargo, on the inner ceiling and on the walls of the container. Condensation occurs on the coldest surface available, and when the warmer air hits a colder surface (the container sealing), moisture release may be as significant as if it was rain falling from the ceiling. Interesting fact: the container floor by itself can hold up to one hectolitre (100 litres) of water!

This may happen every day until the relative humidity (Rh%) is reduced. Mystery solved: when the container arrives and you find that everything is soaked, wet and mouldy, this is almost certainly, what has happened!

Moisture and fungus? Follow these tips!

Although temperature fluctuations are impossible to prevent, there are some tips you can follow to avoid container rain. In general, each container holds a certain amount of moisture:

On the one hand, air always has a basic water content (hot air more than cold), and high fiber cargo, such as furniture, handicrafts and agricultural products, clothing and other fabrics, all contain a certain amount of moisture.

Another surprising fact is that moisture can occur naturally in the packaging material itself (for example, pallets, crates, cardboard boxes). Therefore, when shipping containers overseas, you should consider both the materials of the goods and the packaging and care should be taken to select the suitable packing material for your cargo.

Adequate ventilation also plays an important role in ensuring that moisture does not transform into container rain It is a common mistake to cover the container’s ventilation, thinking that moisture enters from outside. This is a huge misconception – ventilation is designed to remove excessive moisture! Covering it only makes it worse, because as the humid air inside will get hotter and which will result in more container rain

Another very simple way to have less moisture inside the container if the pallets are not standing outside. It is important to know: wood absorbs moisture, especially when the air is warm and humid. Standard EU pallets can absorb up to 20 litres of water and a standard size container contains about 40 pallets. After a quick calculation it is easy to see how this huge amounts of water can generate inside the container – 800 liters is almost as much as two full baths! The price of LCL transport is usually set in kilograms and cubic metres. This means that if your cargo has excess weight, you will pay for nothing. Just by paying attention to these “tiny” details, you can reduce the likelihood of container rain and protect your product from moisture and fungus.

The best method is using dehumidifier

If you are transporting expensive, fragile goods, or if there are many factors that make container rain highly probable, using dehumidifier is of paramount importance. It helps to prevent moisture in the air from reaching a drastic level that can cause damage. This is done by calcium chloride-based absorbing bags, which in its natural state is a liquid brine that is converted into dry matter by the removal of water by heating. If it gets into contact with air, it rapidly and automatically absorbs water from the surrounding air to regain its natural state. So you don’t have to worry, feel free to close the container and open it weeks later, the goods will still be in perfect condition.

Bentonite is also an effective vapor barrier. Its main component is calcium montmorillonite, which is an extremely strong adsorbent that can bind many times its own volume. This natural clay mineral is completely harmless to living organisms and offers an environmentally friendly alternative. Due to its beneficial properties, it is used in many fields such as in electronics, logistics, food and pharmaceutical industries, etc.

Are you also worried about container rain? Would you like to keep your shipment safe?

We offer a variety of solutions to protect your cargo!

Please contact us and we will be happy to answer any questions you may have!


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