Although shipping goods across continents and oceans is a major part of logistics, there are many risks involved. Controlling the moisture content of shipping containers is an important but often overlooked consideration for South African exporters, particularly when shipping perishable goods, food items, agricultural commodities, and other items that are susceptible to mould growth.
Mould and mildew pose serious health risks and can cause great financial losses for exporters. Global industry data shows that cargo damage due to moisture and mildew costs the global supply chain billions of dollars yearly. Excessive moisture can cause “container rain” – or condensation that collects on the ceiling and drops down, which is ideal for mould and mildew growth on goods like coffee, grains, or powdered chemicals.
Therefore, during weeks-long trips over great distances, proactive container temperature and moisture management is vital to maintaining product quality and protecting a company’s financial investment. Custom Bulk Bags (CBB) is a reputable manufacturer and supplier of FIBCs in South Africa. We produce 3.5 million bulk bags a year – all of which can safely hold between 500kg and 2000kg each. Our products are used by exporters due to their breathability and improved mould resistance.
How to minimise mould in shipping containers
Mould prevention is a multi-pronged approach that tackles moisture at its source, in transit, and inside the package.
1. Using FIBCs to improve airflow – Mould prevention is influenced by the kind of internal packaging used. The woven polypropylene fabric used to make bulk bags provides some breathability, in contrast to stiff, non-porous containers that retain moisture. Specialised woven bags can permit a small amount of air circulation for specific products that benefit from ventilation, avoiding an excessive accumulation of localised humidity within the packaging itself.
More significantly, when bulk bags are packed inside a container, their soft, pliable nature facilitates more effective air channelling around the bags than when rigid, tightly packed boxes are used. They are an important part of a moisture control strategy for many goods because of the enhanced airflow, which helps to balance temperature gradients and minimise condensation hot spots.
2. Using container dehumidifiers – Industrial dehumidifying solutions are needed to manage the total environment of the 20- or 40-foot steel containers. Container dehumidifiers are made to extract large volumes of water vapour from the air inside a container.
Throughout the transit time, these massive desiccants that hang along the walls continuously absorb moisture. They function by reducing the container’s internal dew point, which stops condensation (the main source of mould) from growing on the cargo and interior surfaces. Effectiveness depends on choosing the right quantity and capacity of desiccants, according to the size of the container and the moisture content of the cargo.
3. Using container liners – Installing a protective container liner provides a great defence for highly valuable or sensitive cargo. In essence, these liners, which are usually composed of plastic sheeting, form a second, sealed skin inside the container. By creating an insulating barrier that prevents moisture from pouring onto the cargo, they can be especially helpful in avoiding the “container rain” phenomenon.
To reduce solar heat gain and further stabilise the interior temperature and humidity, certain liners are made to be reflective. These liners also have the added benefit of protecting the cargo from outside pollutants and dust.
4. Adding desiccant packets to goods – Placing smaller desiccant packets inside or next to individual cargo units is a highly effective and localised defence against moisture. These smaller packets absorb moisture that is either trapped in the individual packaging or directly emitted by the goods themselves (outgassing), while container dehumidifiers deal with the ambient container air.
Calcium chloride and silica gel are common desiccants. This localised absorption provides a first line of defence against mould growth caused by moisture by keeping the microenvironment immediately surrounding the product as dry as possible.
5. Sealing individual boxes in a dry room – An important step in preventing moisture intrusion is packing products in a dehumidified room and sealing the packaging before transferring them into the container. Before being placed into the shipping container, secondary packaging, such as cardboard boxes, must be sealed in a dry, temperature-controlled environment.
Due to its high hygroscopicity, cardboard easily collects moisture from the atmosphere. When boxes are sealed in a humid atmosphere, moisture is efficiently packed into the container. The initial humidity level can be significantly reduced by ensuring the boxes are securely sealed with packing tape in a dry area. This reduces the quantity of moisture from the environment that enters the sealed container.
The function of a reputable shipping company
If the shipping process is defective, your efforts to prepare a shipment can be completely undone. This emphasises how crucial it is to work with a trustworthy shipping company. Containers are subjected to severe temperature variations over the weeks-long ocean voyage, ranging from the scorching, tropical sun on deck to the frigid marine temperatures below the waterline.
A reputable shipping business should use certain procedures to minimise these variations and, ideally, provide services for data loggers to track temperature and humidity while in transit. These data logs offer recourse in the event of damage and verifiable evidence that conditions stayed within acceptable bounds. Additionally, a trustworthy business will make sure that containers are leak-free, structurally solid, and appropriately ventilated before loading.
Procedure for mould treatment in shipping containers
If mould is found inside a shipping container, prompt and urgent action is required to stop its spread and safely recover the container and cargo:
- Safety precautions – Put safety first. Mould may pose a risk to human health. Before entering the affected container, staff members should put on the proper Personal Protective Equipment (PPE), such as gloves, N95 masks, and protective clothing.
- Removal of affected goods – As soon as possible, separate and get rid of any products that are obviously contaminated or impacted. These items might need to be condemned, cleaned by professionals, or salvaged in accordance with tight regulations, depending on the type of cargo and legal requirements.
- Mould-killing cleaning – The container itself needs to be cleaned completely. Use an approved industrial fungicide or a commercial mould-killing solution, such as a bleach (sodium hypochlorite) and water solution. All interior surfaces, including walls, ceilings, and the floor, must be cleansed aggressively to eliminate all mould spores and residue.
- Drying the container – The container needs to be completely dry after cleaning. To guarantee that all moisture is eliminated from the surfaces and the floor of the container, use industrial fans or dehumidifiers. Any remaining moisture will only encourage the growth of mould.
- Repacking correctly – To avoid recurrence, the container should only be repacked after it has been thoroughly dried, properly ventilated, and replenished with new desiccants.
Order from Custom Bulk Bags today
Being a leading provider of premium FIBCs in South Africa, Custom Bulk Bags knows about the risks associated with long-distance shipping. We are dedicated to helping our clients reduce the dangers posed by mould and dampness. We can customise your FIBCs to improve their breathability or add features like UV protection to preserve the bag’s integrity during external exposure at ports.
We also offer specialised barrier liners to stop moisture from getting into the contents, which greatly improves mould prevention. To optimise ventilation and reduce condensation hot spots inside the container, our knowledgeable staff also offers advice on the various bulk bag types and loading techniques, guaranteeing that your goods reach their foreign destination in perfect shape. Please contact us today for more information about our FIBCs or to get a free consultation.
___
Custom Bulk Bags is a major South African manufacturer of woven polypropylene bags for various industries, including mining, chemicals and agriculture. We are a Level 2 B-BBEE supplier that falls under the ownership structure of Deneb Investments Limited. For more information on our products, contact sales@custombulkbags.co.za.
