Wooden pallets, as fundamental load-bearing tools in logistics transportation and warehousing, often have their lifespan significantly shortened by humid environments. Wood, being a naturally porous material, easily swells, deforms, and even molds after absorbing moisture, leading to a decrease in structural strength. To extend the lifespan of wooden pallets in humid environments, a multi-dimensional moisture-proofing system needs to be built, encompassing material pretreatment, surface protection, optimized storage environment, and routine maintenance. This systematic approach reduces the corrosive effects of moisture on the wood.
Material pretreatment is the foundation of moisture-proofing. Logs must be dried as soon as possible after harvesting to control their moisture content within a reasonable range. If the wood's moisture content exceeds 20%, discoloration fungi and other microorganisms can easily proliferate, causing blue stain or mold. Although many companies cannot achieve immediate drying after harvesting due to factors such as transportation delays and drying cycles, this can be compensated for by optimizing the drying process. For example, a segmented drying method can be used, initially removing surface moisture at a lower temperature and then gradually increasing the temperature to the target value, preventing cracking due to excessive temperature differences between the inside and outside of the wood. For already dried wood, prolonged exposure to humid environments should be avoided during processing to prevent secondary moisture absorption.
Surface protection is a key method to prevent moisture penetration. Applying waterproof coatings or varnishes forms a dense protective film on the surface of wooden pallets, effectively preventing moisture infiltration. Waterproof coatings should be highly penetrating and have good adhesion to ensure they reach deep into the wood fibers for long-lasting protection. For wooden pallets intended for export or long-term outdoor use, a vacuum pressure impregnation process can be used to force-inject anti-mold and preservative agents into the wood, enhancing its resistance to mold and corrosion. Additionally, laying moisture-proof mats, such as plastic film or rubber mats, at the contact points between the wooden pallets and the ground can prevent ground moisture from directly corroding the bottom of the pallets, extending their lifespan.
Optimizing the storage environment is crucial for moisture control. Wooden pallets should be stored in well-ventilated areas away from water sources, avoiding basements or low-lying areas. Warehouses should be equipped with dehumidifiers or air conditioners to maintain relative humidity between 50% and 60%, inhibiting mold growth. When stacking multiple wooden pallets, ensure sufficient space between each pallet to allow for air circulation and reduce moisture buildup. For wooden pallets stored long-term, periodically turn them over and ventilate to prevent localized dampness. Additionally, placing desiccants such as calcium chloride desiccant or activated charcoal in the warehouse can help absorb excess moisture from the air, further reducing humidity.
Daily maintenance is crucial for continuous moisture control. Establish a regular inspection system to promptly identify and address even minor signs of dampness. If mold appears on the surface of the wooden pallets, wipe them with a dry cloth or gently clean them with diluted bleach, then air dry them in a well-ventilated area. For wooden pallets that have already developed mold, use a professional mold remover to spray or brush on them to thoroughly remove the mold before re-treating them with anti-mold treatment. Furthermore, avoid direct contact between wooden pallets and water during handling. In rainy weather or on damp ground, cover them with tarpaulins or wrap them with plastic film to prevent moisture penetration.
Special processes can further enhance the moisture-proof performance of wooden pallets. For example, heat treatment, which involves heating wood to a specific temperature and maintaining it for a period of time, can reduce the wood's moisture content and kill internal fungi. However, it's crucial to control the temperature and time to prevent cracking. For exported wooden pallets, fumigation can also be used, employing chemical agents to kill insect eggs and fungi. However, its effectiveness is relatively short, requiring combination with other moisture-proofing measures.
The selection and use of desiccants must be scientifically sound. Container desiccants are internationally recognized moisture-proofing tools that can be placed inside the wooden pallet packaging to absorb moisture during transport. However, their absorption capacity is limited, requiring regular replacement or replenishment in extremely high humidity or long-term transport scenarios. Furthermore, some desiccants may contain chemical components; compatibility with the wooden pallet material must be ensured to avoid corrosion or discoloration.
Through systematic measures such as material pretreatment, surface protection, optimized storage environment, routine maintenance, application of special processes, and the scientific use of desiccants, the adaptability and durability of wooden pallets in humid environments can be significantly improved. These measures not only extend the lifespan of wooden pallets and reduce replacement costs, but also improve logistics efficiency, ensure the safety of cargo transportation, and provide strong support for the sustainable development of the logistics industry.
