Moisture Problems: An Unseen Hurdle of Wood Transportation

It’s easier than you think for unwanted moisture to work its way into a shipping container and cause problems with your load of wood.

Effective moisture management, however, can prevent those problems. An environmental data logger allows you to be proactive by continually monitoring ambient temperatures and humidity. And if damage were to occur, you would have the information to track how it happened.

We’ll explore all of this in the following areas:

• Moisture’s impact on transported wood
• Methods for preventing moisture problems while shipping wood
• The best way to monitor moisture while transporting wood

We’ll begin with how moisture affects wood during transportation.

Moisture’s Impact on Transported Wood

If not sealed properly, shipping containers with moisture inside are almost a given. And if not properly managed, the moisture can cause a lot of problems for wood. This includes issues like mildew, mold, and warping (think twisting, bowing, or cupping).

Another problem that can arise is a phenomenon called container rain. This is where the container develops its own little ecosystem, causing condensation to form inside and fall like rain.

Cargo sweating is very similar. It occurs when condensation forms on the container, like droplets on the outside of a glass of water.

Even if the wood has been dried to an appropriate moisture content previously, it can still develop moisture-related problems during shipping.

Moisture works its way into the shipping containers in a couple ways:

• Moisture can seep into the shipping containers from the outside. Shipping containers are sometimes waterproof but not always airproof. Water vapor can penetrate where water droplets can’t, wreaking havoc inside the containers.
• Any interior wooden components of the shipping containers themselves may have a higher moisture content than the wood being shipped. The moisture will move to the wood with the lower moisture content—the wood being shipped—and cause problems if the wrapping around the wood isn’t sealed. Also, the wood pallets the lumber sits on could be green, which can release a tremendous amount of moisture into the air.

So, how do shipping companies prevent moisture problems?

Methods for Preventing Moisture Problems While Shipping Wood

Because of the frequent moisture problems associated with shipping, shippers have developed a few methods for keeping moisture in check. We feel the best of these methods is moisture monitoring.

We’re going to talk about this and other methods, but we’ll start with an initial preventative measure: kiln drying the wood.

Kiln drying

Kiln drying involves drying wood in a kiln down to a specific moisture content, usually to certain percentages below 20%, depending on the future use. (To meet the ISPM15 standard, raw wood being shipped between countries must be heat-treated for a specific time anyway.)

Many people think that once wood has been kiln-dried, it will always be ready to use.

Unfortunately, this is not always the case. No matter how much a piece of wood is dried, it will always gain or release moisture when exposed to environments with a different moisture content. This includes changes that might happen during transportation.

Wrapping the wood

As we’ve already hinted at, a good way to prevent outside air from harming a shipment of lumber is to wrap the lumber. Usually, this is done with a plastic vapor barrier, which acts as a wall against invading moisture, whether it’s seeping into the container or coming from green pallets.

Shrink wrap can do the same, although it may develop holes easier than a plastic vapor barrier if it’s bumped or scraped against something else.

Now, let’s look at our favorite method.

Moisture monitoring

Continuous monitoring is the best way to keep wood moisture at bay during transportation.

Before loading the wood to be shipped, use a wood moisture meter to measure its moisture content. Ideally, it shouldn’t be above 8%—but 18% is the highest, no matter the conditions. Percentages above this indicate the wood may not have been dried properly and may not meet ISPM standards.

At the end of the shipment, have the receiving person measure the moisture levels again and compare them to the levels taken at the beginning of the trip.

If they are higher, you’ll know more moisture seeped in somehow. If they are lower, you’ll know moisture got out. If you see any significant changes, you will know that future shipments may need additional moisture controls.

Aside from using a moisture meter to check the wood, we also recommend monitoring the temperature and humidity of the shipping container itself.

That’s where monitoring technology comes in.

The Best Way to Monitor Moisture While Transporting Wood

One of the best ways to monitor temperature and humidity throughout the transportation of wood is through something that can take regular automated measurements. And our Smart Logger™ does that very thing.

The Smart Logger is an affordable device that has revolutionized moisture management. All you have to do is set it in the shipping container. It will discretely log the temperature and relative humidity of the container, taking readings as often as you set it to.

It’s essential for getting an accurate glimpse of how the humidity and temperature changes affected your wood, particularly if you sustained significant damage on recent shipments.

Smart Logger’s Bluetooth® capabilities allow you to receive all the data on your smartphone when you’re within range. And even if you’re out of range, the Smart Logger will continue to monitor conditions—which the person at the receiving end can later view as a report.

The Smart Logger pairs with a mobile app that allows you to monitor relative humidity and temperature during transportation whenever the mobile device is within Bluetooth range.

If your load sustains damage during shipping, the Smart Logger can help you sort out what happened. You can check the recorded day against weather conditions during the trip and shipping logs to find the cause and piece together the story behind the damage.

Then in the future, you can change your techniques to help prevent such disasters.

Before the Smart Logger, you would have had no idea when things went wrong and what caused the problem. But the data in the Smart Logger gives you the pieces to help you solve that mystery.

Optimal Moisture Management with Wagner Meters

The journey of wood transportation requires plenty of planning beforehand. After all, you’re dealing with Mother Nature, who has an uncontrollable mind of her own!

That means changes in temperature and humidity are unpredictable and difficult to control.

A number of different solutions are available with varying degrees of success. Solutions like making sure that the shipping pallets and the wood being shipped are properly dried. And keeping the wood wrapped as a further barrier against moisture.

However, continuously monitoring moisture conditions with the Smart Logger can help you keep close tabs on what’s happening to your load of wood. If moisture damage occurs, you can connect the dots between time, humidity, and temperature.

And if both the shipping and receiving parties have the Orion® 950 to measure the wood’s moisture content before and after shipping, you’ve got an excellent force for moisture management during transportation.

How could these tools elevate your moisture management game?

Check out our Smart Logger and Orion 950 before your next transport!

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.