Damage & prevention Moisture damage risk Type of moisture damage Container Rain Moisture damage costs Why calcium chloride Our prevention process Peace of Moisture Mind AbsorTest Industries we protect Sustainability by prevention Products All Products Container desiccants Absorpole Absorbag AbsorGel Hanging AbsorGel Blanket AbsorGel Max & Compact AbsorGel Sheet In-box desiccants AbsorGel Pouches AbsorGel Sheet AbsorTerra Accessories Packaging Talk to an expert Insights Moisture Magazine FAQ Webinars Sustainability Sustainability for Clients Sustainability at Absortech About Our company Our organization R&D Quality and production Our people Find an Absortech contact Transparency & Accountability News Contact Language Mould and mildew Mould and mildew are among the most common and costly consequences of uncontrolled moisture during transport and storage. Once mould develops, it is difficult, expensive, and sometimes impossible to remediate, often resulting in rework, delayed deliveries, or scrapping of goods entirely. The risk is particularly high for paper- and wood-based packaging materials, natural textiles such as cotton and wool, and even polyester fabrics, leather, as well as organic and agricultural goods, where moisture, temperature, and exposure time combine to create ideal conditions for biological growth. By controlling humidity, however, it is possible to significantly reduce these risks and protect supply chain integrity. Why mould and mildew occur 1. Temperature, moisture and time Mould growth requires three basic conditions: moisture, suitable temperature and a source of organic nutrients. When these conditions are maintained over time, mould can grow. While temperature affects the speed of growth, relative humidity (RH) is the decisive factor. Optimal temperature range for mould growth is 20–30 °C Mould can still grow between 0–40 °C Relative humidity levels determine risk: Below 65% RH: very low mould risk Above 75% RH: medium to high mould risk Under favourable conditions, mould can begin to develop within 24–48 hours. When elevated humidity persists over time, naturally occurring mould spores can germinate and develop into active mould growth on packaging materials or directly on products. 2. Packaging materials amplify the risk Many materials used in logistics and transport are hygroscopic, meaning they readily absorb moisture from the surrounding air. Common examples include cardboard and paper-based packaging, wooden pallets and crates, and wood-based load carriers. Once moisture is absorbed, these materials create microclimates that promote mould growth and allow contamination to spread from packaging to products. The risk is therefore not limited to the product itself. Mould growth on packaging materials can lead to rejection of otherwise unaffected goods, particularly in food, hygiene, and pharmaceutical supply chains. Even when products are stored in protective or transparent packaging, mould on external packaging can result in quality claims or rejection at destination, despite the product itself remaining unaffected. The images below illustrate how moisture absorbed by packaging materials can lead to visible mould growth during transport. As shown, mould often appears on exposed surfaces, edges, or folds of packaging, where contamination can spread and result in quality claims or rejection, even when the packaged goods themselves remain unaffected. 3. Garments, textiles, and leather goods Garments, textiles, and leather goods are particularly sensitive to elevated humidity due to the hygroscopic nature of fibres. Materials such as cotton and leather readily absorb moisture, creating conditions that support mould growth, odour development, and visible staining. Unlike agricultural products, rejection of garments and leather goods is often driven by aesthetic, sensory, and brand-quality criteria rather than safety thresholds. As a result, even limited mould growth or surface contamination can render products unsellable. Mould risk in these goods is strongly influenced by relative humidity levels and exposure time. Once moisture is absorbed into fabrics or leather, drying becomes difficult during transit, increasing the likelihood of mould development if humidity is not actively controlled. 4. Organic and agricultural products are especially vulnerable Agricultural and organic products represent one of the highest mould-risk categories in global logistics. This includes: Grains, seeds, coffee, cocoa, spices, and animal feed Food ingredients of plant origin Natural raw materials for further processing These products naturally contain residual moisture and organic nutrients. Even small increases in ambient humidity can push them beyond safe thresholds, particularly during long ocean transport or extended storage. In many cases, mould contamination of agricultural products results in automatic rejection, loss of food-grade status, or mandatory disposal. PRODUCT MOULD RISK THRESHOLD* COFFEE BEANS 65% RH COCOA 70% RH GRAINS** 60-70% RH GARMENTS 65–75% RH (DEPENDING ON THE FABRIC) PAPER- & WOOD-BASED PACKAGING 70-75% RH * RH thresholds are indicative and may vary depending on product moisture content, packaging, temperature, and exposure time. ** Risk varies by grain type and processing condition; prolonged exposure above threshold increases spoilage. 5. Ocean transport and long storage increase exposure Ocean-going containers are exposed to temperature fluctuations, condensation events, and prolonged periods of high humidity. Combined with long transit times and pre- or post-shipment storage, goods may remain in mould-critical conditions for weeks. Mould risk is highest during specific stages of transport, particularly during tropical or monsoon-season crossings, port delays in humid climates, and temperature transitions associated with refrigerated storage. The absence of visible mould at destination does not necessarily indicate that contamination has not occurred. In food and feed products, spores or mycotoxins may be present before visible mould develops, creating quality and compliance risks even when products appear visually acceptable. What happens when prevention fails Once mould or mildew is detected, remediation options are limited and costly. Ozone or chemical treatment, with varying effectiveness Repacking, if contamination by mould is limited to external packaging Scrapping, when contamination cannot be safely removed Beyond direct costs, mould incidents often lead to delivery delays and supply chain disruption, quality claims and disputes, and/or loss of customer confidence and brand reputation. For food, feed, and organic products, rework is often not permitted, making prevention essential. Different ways to mitigate mould and mildew growth risk Improved hygiene and handling Keeping goods, packaging, and storage environments clean reduces available nutrients for mould growth. However, cleanliness alone does not remove moisture and therefore cannot fully eliminate mould risk. Treated or barrier packaging Some companies attempt to reduce mould risk by using coated or treated packaging or adding plastic liners or moisture barriers. While sometimes effective, these solutions increase cost and material usage, complicate recycling and conflict with sustainability and Packaging and Packaging Waste Regulation (PPWR) requirements. Desiccants: addressing the root cause Desiccants actively absorb moisture from the air, reducing and stabilising relative humidity inside containers and packaging environments. By maintaining RH inside the container below mould-critical thresholds, desiccants: Prevent mould and mildew growth Protect both packaging and products Control conditions throughout the entire journey Mould spores are naturally present in the environment and cannot be fully eliminated during transport and storage. However, mould can only grow and spread when conditions allow it to do so. Elevated humidity is the key factor that enables mould growth. Desiccants are a preventive solution that addresses the root cause of mould growth: excess moisture. Pre-shipment conditions for cargo are also critical, as products must be properly dried before loading and shipping. While desiccants effectively control the container environment humidity during transport, they cannot compensate for cargo that enters the supply chain with excessive internal moisture. Our solution: mould prevention through humidity control Mould and mildew develop when relative humidity remains too high for too long. Once detected, remediation is costly, and for organic or agricultural products, often impossible. Absortech prevents mould by controlling humidity before growth can start. Using container and in-box desiccants, we help keep relative humidity below mould-critical levels throughout transport and storage, protecting: Organic and agricultural products Cardboard and paper-based packaging Textiles, leather, and other natural materials and garments This preventive approach eliminates the need for rework, reduces waste, and supports sustainable packaging choices. With our Peace of Moisture Mind® (POMM) approach, we design a mould-specific moisture protection strategy based on your cargo, packaging, and route. Speak to us to reduce mould risk before it becomes a problem.
