How to Prevent Costly Moisture Damage to Wooden Pallets During Shipping

Wooden pallets can carry excess moisture that damages the products placed on them.

In a world of easy travel and transportation, we have access to products of every kind via shipping.

But the shipping process doesn’t come without its challenges—one of them being moisture.

Moisture not only affects the pallets themselves. It can also damage the products placed on them. And that can impact your bottom line.

Even if the products were in tip-top shape when they were prepped for shipping, that won’t matter to your customers. If damaged goods are what they end up receiving, then you’re likely to receive their frustration and their demand for refunds.

So, if you’re a company that uses wooden pallets when you ship your products, here’s how to prevent these issues—especially when it comes to moisture content measurement.

You’ll learn:

• How moisture affects wooden pallets
• Why you should test their moisture content
• How to prevent moisture issues

How Moisture Affects Wooden Pallets and Products

Excess moisture in wooden pallets can become a home for mold and lead to the decay of the wood. These issues can result in problems with the strength and integrity of the pallets and affect the products themselves.

Marshall S. White, director of a pallet and container research lab at Virginia Polytechnic Institute and State University, wrote out a whole list of effects moisture can have on pallets.¹ It…

• reduces pallet strength and stiffness
• adds useless weight
• corrodes metal products
• causes odor, which contaminates products
• causes staining of products
• leads to wood shrinkage
• causes splitting and warping of pallet parts
• loosens joints
• causes mold and mildew growth

But those are not all.

Another issue is cargo sweating or container condensation.

When the outside of a shipping container is cooler than the dewpoint of air inside the container, the inside begins to form water droplets—condensation or sweating.² It’s like your car windows fogging up when it’s cold outside and warm inside.

The condensation then causes little water droplets to run down the sides of the container, possibly damaging the pallets and the products in them.

How does this relate to pallets with extra moisture?

See, three factors are necessary for cargo condensation to happen: (1) a difference in temperature, (2) a source of moisture, and (3) a pathway for the water vapor to move to the surface.³

Wet pallets, unfortunately, are a source of moisture that can make cargo condensation possible.⁴

That’s one major reason for shipping companies to measure the moisture content of their pallets.

Why You Should Test the Moisture Content of Pallets

Test the moisture content of pallets before shipping to prevent container condensation during shipping.

Moisture testing protects your products from moisture-related issues during the shipping process. It allows you to know the true moisture content of your pallets and get them to a safe level that won’t cause damage. This way, you’ll maintain product quality while saving the costs of damaged goods.

You may think, Well, why waste the time? If damage does occur, insurance will cover it.

But that’s not necessarily true.

Damage due to condensation or cargo sweat is usually not an “insured peril,” meaning insurance won’t cover it.⁵

And you’ll be left to foot the bill to replace the damaged item.

For this reason, TimCon (Timber Packaging and Pallet Consideration) best practices recommend an upper moisture content threshold of 19%, plus or minus 3%. A moisture content under 22% will typically prevent mold growth.⁶

If the wooden pallets will be holding corrosion-sensitive metal, 20% or less is ideal.⁷

So let’s take a look at the best way to check that pallets have reached these levels.

How to Prevent Moisture Issues with Wooden Pallets and Shipping Cargo

Testing wooden pallets with a moisture meter before shipping is a key step in preventing moisture damage during shipping. The goal is to make sure the pallets have reached 22% moisture content or less (Also check for any regulations your company may need to follow).

The best way to do this is with a pinless moisture meter that allows you to scan a pallet and get moisture content results in seconds. You’ll be able to test large quantities of pallets without adding several more steps to your packing process.

Test throughout the boards of the pallet, rather than just at the ends.

Then, you can be sure you’re getting a representative picture of the moisture content.

If you can, check the pallets before purchasing them to avoid acquiring any wet ones.

Then, measure the moisture again before loading them with products. This gives you an opportunity to remove a pallet that could otherwise cause problems in the shipping container.

Also, be conscious about where you’re storing the pallets.

Keeping them outside is probably not the best idea unless you’re in a very dry climate.

Wood tends to absorb moisture from its environment. According to one source, “a standard EUR-pallet can absorb up to 20 litres of water, and a standard 40 feet container accommodates about 40 pallets. Doing the maths, you will realise there can be a huge amount of water inside the container – 800 litres of water is almost like having two full bath tubs with water!”⁸

Storing pallets in a dry environment and testing them before use will prevent this amount of moisture from ending up in your shipping container.

Protect Your Products and Profits

Excess moisture in wooden pallets is not just a matter of damaging the pallets themselves. It’s a risk to the products within.

So, when you take precautions like testing moisture content and storing pallets in a dry area, you’re extending the life of the pallets as well as protecting the products.

That means protecting your investment and the profits you’ll receive from those products.

Visit our shop to take a look at our high-quality pinless moisture meters and find one that suits your business.

1. White, Marshall, “Water in Wood Pallets: The Facts Behind the Opportunity Available in Dry Pallets,” Industrial Reporting, Inc., 1997.
2. “The Effect of Water Moisture Damage on Containerised Cargo,” International Institute of Marine Surveying, Dec. 9, 2015.
3. Ibid.
4. Ibid.
5. Ibid.
6. Pallets and Packaging Best Practice Guide: Dry Pallet–Process Standard for Timber Pallets, TimCon.
7. White, “Water in Wood Pallets: The Facts Behind the Opportunity Available in Dry Pallets.”
8. “Container Rain – What It Is and How to Prevent Moisture Damage,” Greencarrier, Oct. 28, 2015.

Jason Wright

Jason Wright, Business Development Specialist for New Products, joined Wagner Meters in 2019. He comes to Wagner with over 35 years of experience in the flooring industry.