Pallet Mold Season Is Around the Corner: Is Your Supply Chain Ready?

Wood pallet handling and storage best practices can help prevent wood pallet mold problems for you and your customers.

Wood pallet salespeople will tell you that come Spring, customer mold problems are as predictable as the warm weather that follows its arrival. For logistics professionals, pallet handling and storage practices at the plant or warehouse that work great in colder weather can be a problem as the temperature climbs. With this challenge in mind, ensure that you make the necessary adjustments.

To take a step back, it helps to understand the basic recipe for mold. It requires a combination of oxygen, adequate temperature, a food source (your wood pallets) and free or liquid water. Here’s what you need to know. By controlling the exposure of wood pallets to moisture, mold problems can be largely avoided.

One misconception that is important to clear up, as PalletOne aptly pointed out in this blog, is the belief that ISPM 15 heat treatment can be an effective remedy to mold problems. Keep in mind that heat treatment (a minimum of 30 minutes at a core temperature of 56 degrees Celsius) is designed to kill insects living in the wood, so that they will not be inadvertently transported internationally, putting forests abroad in danger of infestation. Rather than reducing the threat of mold, heat treatment can make it worse by drawing moisture and sugars to the wood surface. Once removed from the heat chamber, a convenient surface environment has been created for mold spores to colonize. 


This is an example of bluestain, an occurrence that does not present a health risk to pallet handlers or consumers when associated with wood pallets. Source: NWPCA.

So what wood pallet handling and storage steps can you take to minimize the threat of mold? Here are some basic mold prevention tips, as shared by PalletOne:

  • Unload trailers of wood pallets quickly, and get them undercover. Don’t use that dark, humid trailer for pallet storage. Keith Reinstettle, Vice President of Sales at PalletOne Inc. observed that your storage trailer can easily turn into an unintended science experiment. Likewise, ensure that pallets are not staged outside if it is raining. Just brief exposure to moisture can provide the conditions needed for fungus to germinate, even after pallets have been subsequently moved to dry storage.
  • Pay attention to storage practices. It is all too common for pallet users to make the mistake of stacking pallets in a dark corner of a facility. Instead, store pallets in dry, well lit and ventilated locations. For stringer pallets, it makes sense to orient the open ends in the direction of air movement to improve airflow through them. And sticking with stringer pallets, avoid placing stacks of them too tightly together on the stringer side, which could impede airflow through them. Finally, storing stacks of pallets at least 6 to 8 inches off the floor helps eliminate the risk of pallets getting wet from water puddles.
  • Not all discoloration in wood is mold. Take time to understand the difference between bluestain and mold. Buestain creates a bluish or greyish discoloration in wood but is not associated with human health concerns or pallet performance issues. According to an NWPCA brochure (You can download it here), “Mold grows on the surface and can be brushed off or smeared, whereas blue stain penetrates deep into the wood and cannot be removed.”
  • Chemical treatment for mold prevention might be an option. There are several EPA registered as well as FDA approved or exempted ingredients that can be used to guard against mold. Check with your pallet supplier for more details.

Bottom line, Spring is coming. Make sure you have your warm-weather pallet handling and storage routines in place to prevent wood pallet mold problems in your supply chain.