Guru – How-to Tips from Industry Experts: Smart Solutions to Get Ready for Mold Season

When the weather warms up in the spring – as it is doing now – and conditions are right, mold spores can quickly colonize on wood surfaces. In a matter of days, mold can spread from idle lumber or pallets to contaminate materials and equipment. As a result, employee health and safety, as well as sensitive products, can be compromised. 

 

The Science Behind Mold Growth on Pallets

Mold is a fungus that grows in the form of multicellular filaments called hyphae. There are more than 100,000 species of mold. They play an important role in helping to decompose wood and other plant matter. However, mold becomes a problem when it takes root on lumber and pallets.

Wood is a food source for mold. Besides a food source, the mold also needs oxygen, moisture, and the right temperature in order to grow. The most common approach to controlling mold on lumber and pallets is to regulate the moisture content of the wood. For best results, wood moisture content should be kept under 19%.

A common misconception is that heat-treating pallets for ISPM-15 compliance will prevent mold. The heat-treating process – heating the wood to a core temperature of 56 degrees C (132.9 F) for 30 minutes – is designed to kill insects that inhabit wood. The ISPM-15 regulation was introduced to prevent wood-eating insects from being transported inadvertently from one country to another via infested wood packaging. The heat-treating process does not prevent mold. In fact, after pallets have been heat-treated, they provide a favorable environment for mold spores to colonize.

Partners in hygiene-sensitive supply chains – manufacturers, distributors and retailers – are becoming increasingly sensitive about mold on pallets. Mold on pallets presents not only an occupational health and safety concern, but it also risks the quality and safety of goods that ship on pallets. This is especially a concern for pharmaceutical and food supply chains.

 

Common Ways to Prevent Mold Growth; Proper Storage Is Key

Basic steps for preventing mold on pallets start with keeping them dry. Here are some recommended best practices:

• Identify the real culprit. Make sure that mold is actually the problem. Wood may become discolored, but the reason may not be mold. Blue stain creates a bluish or greyish discoloration in wood, but it is not associated with health concerns or pallet performance issues. According to a brochure by the National Wooden Pallet & Container Association, “Mold grows on the surface and can be brushed off or smeared, whereas blue stain penetrates deep into the wood and cannot be removed.

• Proper storage is a must. Store pallets where they will stay dry. Even short exposure to rain can be problematic. If the wood becomes wet even briefly, it can be enough for a fungus to start germinating, grow into the wood, and produce spores on the surface. By then the wood might be dry, but mold will already be present.

• Elevate pallet stacks if possible. Keeping pallets off the ground or floor can prevent water from wicking up from any puddles on the floor or ground.

• Humidity is not your friend. Do not store pallets in a trailer van. Dark, warm, humid trailers can quickly become incubators for mold growth. Coordinate pallet deliveries with trading partners so that pallets can be quickly unloaded and placed into dry storage.

• Ventilation and air flow aids drying. Store pallets in a well-lit, dry, ventilated environment. Covered storage is critical for keeping pallets dry. For outdoor storage sheds, stringer pallets should be aligned in the direction of prevailing winds to help improve airflow. For indoor storage, choose a well-lit, ventilated part of the warehouse. Allow adequate spacing between rows to further improve ventilation. Consider installing fans to circulate air to assist the drying process.

• Purchase dried lumber that is below 20% moisture content. Consider using kiln-dried softwood lumber. More industries are transitioning to softwood pallets made of kiln-dried lumber. While some applications still require hardwood, kiln-dried softwood pallets can be designed to deliver comparable service – without the mold challenges associated with heat-treating.

 

Lumber and Pallet Treatments Are a Game Changer

WoodLock Bio-Shield is an effective treatment for lumber and pallets to prevent mold. It was developed to treat lumber used in construction in order to prevent mold growth in new homes. Its inventor, Jim Stanley, saw the need for a non-toxic mold inhibitor for lumber and pallets and reformulated the product for this application.

WoodLock Bio-Shield is similar to other mold prevention products in that it is applied by spraying or dipping onto green lumber – hardwood or softwood – and finished pallets, crates, and boxes. It is uniquely effective in preventing mold by utilizing a polymer emulsion that forms an ionic bond with the formula’s antimicrobial agent and a mechanical bond with the wood, effectively ‘locking’ out mold spores by stopping gestation. The active ingredients of WoodLock Bio-Shield are bio-available at just 10% humidity with higher availability at higher humidity levels, so the better the conditions are for mold growth, the harder it works. The ingredients are held on the surface of the wood by the polymer, which softens, allowing the antimicrobial agent to become more bio-available.

This unique formula has a zone of inhibition up to 2-3 mm away, ensuring that nearby areas are protected even if a board is not 100% covered. The polymer seals as it dries, so it can work repeatedly, and because WoodLock Bio-Shield is not water-soluble, it continues to protect wood from mold growth even after multiple wet-dry cycles.

The performance of WoodLock Bio-Shield was validated by Virginia Tech using the ASTM D4445 Laboratory Method for Evaluating the Mold Resistance of Wood-based Materials.

Besides its unique effectiveness, WoodLock Bio-Shield is formulated with active ingredients that are on the EPA Safer Alternative List and are listed as FDA GRAS (Generally Regarded as Safe). The formula contains no hazardous materials or carcinogens and is non-flammable and non-corrosive. As a result, WoodLock requires no additional safety precautions and can be used indoors and around sparking machinery. It will not damage containers, forklifts, or other equipment. Empty WoodLock Bio-Shield containers can be recycled in standard municipal recycling streams; no special disposal protocols required.

Editor’s Note: Evan Karlewicz is sales manager for Pallet Machinery Group (PMG) in King George, Virginia. For more information about WoodLock Bio-Shield, call PMG at (540) 644-9220 or visit the website at www.palletmachinery.com.

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Evan Karlewicz

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Pallet Enterprise November 2024