The Importance of Moisture Content in Wooden Packaging and Pallets: What is "Dry"?
- Alfredo Vázquez
- Nov 20
- 5 min read
In the packaging and logistics industry, wood is a fundamental material due to its strength, versatility, and sustainability.
However, its optimal performance depends on a critical factor that is often underestimated: moisture content (MC).
What does it really mean for wood to be "dry"? And why is this detail vital for preserving your products and ensuring the efficiency of your supply chain?
At Kayak Packaging, as experts in packaging solutions, packing and wooden pallets, we know that understanding and controlling the moisture level of wood is the basis of safe and compliant packaging.
What is Moisture Content and why is it crucial in wood?
The moisture content of wood is defined as the ratio between the weight of water contained in the wood and the weight of the anhydrous (completely dry) wood. It is expressed as a percentage.
Unlike other materials, wood is hygroscopic, meaning it absorbs and releases moisture from the environment. Therefore, "dry" does not imply the total absence of water, but rather a balance with the surroundings or a specific level for a particular purpose.
Key concepts for understanding moisture in wood used in pallets and packaging
Green Wood: Freshly cut, with a very high moisture content (often >30%). It is unstable and prone to warping.
Fiber Saturation Point (FSP): Around 25-30% moisture content. This is the point where the cell walls are saturated with water, but there is no free water in the cell cavities. Below the FSP, wood begins to shrink and gain strength.
Air-Dried Wood: Left to dry naturally, its moisture content is balanced by the humidity of the outside air (12-20% depending on the climate).
Kiln-Dried Wood: Dried in controlled chambers to achieve a specific and uniform moisture content (typically 6-12% for furniture, or higher levels for industrial packaging, such as 19% or less for ISPM 15). This is the most controlled and reliable method.
The Importance of Humidity Levels for Wooden Packaging and Pallets and Their Preservation
Controlling the moisture content in wood used for packaging is essential for several reasons:
Stability and Structural Resistance:
Wood with the appropriate moisture content is more stable. "Green" or very wet wood is prone to shrinking, swelling, warping, or cracking as it dries, compromising the integrity of the packaging.
Dry wood is stronger and maintains its dimensions better, ensuring that its packaging retains its shape and protective capacity during transport.
Greater Fastener Adhesion: Dry wood allows nails, screws, and other fasteners to hold more firmly, contributing to the robustness of the packaging.
Weight Reduction and Shipping Costs:
Water adds significant weight to wood. Using wood with a controlled moisture content reduces the overall weight of the packaging, which directly translates into lower freight costs , especially for air or long-distance shipments.
Prevention of Fungal Growth and Pests:
Damp wood is an ideal breeding ground for fungi, mold, and bacteria , which can degrade the wood and, more critically, damage or contaminate the packaged product.
Insect pests are also attracted to wood with high moisture content. Proper drying is a natural barrier.
Facilitating Compliance with ISPM 15 Regulations:
For the heat treatment required by ISPM 15 to be effective, the wood must reach an internal temperature of 56°C for at least 30 minutes. A high initial moisture content can hinder heat penetration and prolong the time required to reach the internal temperature.
Protection of the Packaged Product:
Moisture from wood can transfer to moisture-sensitive products (electronics, textiles, food, etc.), causing corrosion, mold, or irreparable damage. Using dry wood minimizes this risk.
Measurement and Preservation Techniques for Wood Packaging
The moisture content of wood is easily measured with specific moisture meters. For preservation, beyond drying, some good practices are:
Storage in Covered and Ventilated Areas: Wood should be stored in covered areas, protected from rain, splashes, or condensation. Good cross-ventilation helps maintain stable humidity levels in the air.
Elevation of the Floor: Use pallets, racks, or structures that keep the wood at least 10–15 cm above the floor. This prevents contact with damp or cold surfaces that can transfer moisture by capillary action.
Use of Breathable Waterproof Covers If you need to cover the wood, use materials that block water from entering but allow air circulation, such as micro-perforated tarpaulins or technical covers.
Environmental Control in Enclosed Warehouses: Maintain relative humidity below 60% using ventilation systems, dehumidifiers, or exhaust fans. The use of sensors to monitor critical conditions is also recommended.
Avoid sudden temperature changes. Thermal fluctuations can cause condensation on the surface of the wood. It is recommended to maintain a temperature as stable as possible in storage areas.
❌ Common Mistakes to Avoid
Use of Stretch Wrap or Closed Plastic Wrap: Although it is common to wrap wood in stretch wrap for transport, this material traps internal moisture and generates condensation, especially if there are temperature variations. This can cause the wood to become damp even if it was initially dry.
Direct Storage on the Ground or Outdoors Leaving wood directly on the ground or without a roof exposes it to subsoil moisture, runoff, or even morning dew, accelerating moisture reabsorption.
Prolonged Storage without Inspection: Not periodically checking the moisture content of wood stored for a long time can lead to unpleasant surprises: warping, mold, or premature deterioration.
Kayak Packaging's Commitment to Quality and Preservation of your wooden pallets and packaging.
At Kayak Packaging, the quality of the wood and its proper treatment are cornerstones of our service. We ensure that every pallet, box, or crate meets the highest international standards, guaranteeing its durability, reliability, and exportability.
FSC Certified Wood: We source wood from sustainably managed forests, guaranteeing not only quality, but also environmental responsibility.
ISPM 15 Treatment: All our wood is heat-treated to ensure compliance with international regulations, facilitating your export operations.
Strict quality controls: We constantly check the condition of the wood upon arrival, during storage and prior to use.
Expert Design: Our packaging engineers consider all factors, including moisture content and preservation needs, to design solutions that optimally protect your goods.
Choosing the right partner for your wood packaging means choosing a partner that understands the science behind wood and its impact on your supply chain.
Do you need packaging that guarantees protection and compliance?
Contact Kayak Packaging today for personalized advice.
Forest Products Laboratory. (2010). Wood handbook: Wood as an engineering material (General Technical Report FPL–GTR–190). US Department of Agriculture, Forest Service.https://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr190.pdf
Simpson, W. T. (1991). Drying wood: Principles and practices . In Forest Products Laboratory (Ed.), Dry kiln operator's manual (Agriculture Handbook 188). US Department of Agriculture, Forest Service. https://www.fpl.fs.fed.us/documnts/usda/ah188.pdf
Glass, SV, & Zelinka, SL (2010). Moisture relations and physical properties of wood . In Forest Products Laboratory (Ed.), Wood handbook: Wood as an engineering material (pp. 4.1–4.19). US Department of Agriculture, Forest Service.https://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr190.pdf
Walker, J.C.F. (2006). Primary wood processing: Principles and practice (2nd ed.). Springer. https://doi.org/10.1007/1-4020-4393-7
Hasburgh LE, Craft ST, Van Zeeland I, Zelinka SL. Relative humidity versus moisture content relationship for several commercial wood species and its potential effect on flame spread. Fire and Materials. 2019;43:365–372. https://doi.org/10.1002/fam.2707
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