Wooden pallets are among the most commonly used materials handling components. Over 400 million are produced annually in the U.S. using more than 6.5 billion board feet of lumber. Most pallets are bought to hold products processed within and then shipped from facilities. The majority of these are one way trips, so the purchaser rarely ever sees the pallet again.

Because of that, buyers do not give much attention to pallet quality, as long as they survive that initial trip. Price is often the overriding factor in pallet selection.

Yet pallets have proven to be among the world's most recycled products, lasting long after their original handling job. Often, the differences between pallets that make dozens of trips and those that make only a few are due to the selection of wood materials and how they are constructed.

These two factors are especially important for users who buy pallets for internal slave purposes and closed-loop systems. Often these pallets are used in automated equipment, so their reliability must be counted upon to keep product flowing. Quality matters greatly for these pallet buyers. Knowing about the wood that goes into purchased pallets and the other variables that affect them goes a long way to matching the right pallet to the job.

The wood used in pallets varies greatly, though all is low-grade lumber, far below the quality used to make furniture. But then again, no one really wants to sit on a pallet.

"You do not need to make a pallet out of perfect wood. That is overkill," says Dr. Bob Bush of Virginia Tech.

Bush has recently completed a study on woods used in pallets. Among his findings are the strength characteristics of the various wood species from which pallets are made, as well as specific usage. More than twice as many pallets are made from hardwoods than are constructed from softwoods. Over 50% of hardwood construction uses a combination of wood species.

"Typically you get whatever is available to the manufacturer that day," says Bush. "In the North that might be aspen, and in the South it might be gum."

About 27% of hardwood pallets are made from oak. These hardwoods are durable and offer a higher degree of protection than most softwoods.

Softwoods are appropriate for products that do not require a stringent level of durability. Cases of paper towels, for instance, can be very appropriately moved using softwood pallets.

The most common softwood available is southern pine. Softwood pallets have the advantage of being relatively strong and usually lighter to maneuver than hardwood pallets. They are ideal for one way trips with light to medium loads.

Some pallets are also produced using a combination of hard and soft woods.

"Overall strength of wood is correlated to the density of wood," says Bush. "Contrary to what many believe, the faster a hardwood tree such as oak grows, the more dense it is."

Unless you ask for dried wood, you will typically receive green wood. Green wood may be more resilient to impact damage, but has less supportive strength. Since a green pallet has a higher moisture content, it can potentially damage products that rest upon it. Sensitive products should be placed on either kiln dried or air dried pallets.

Air dried lumber typically loses from 0.2 to 1% of moisture per day. Wood actually gets stronger once dried and stays strong throughout its useful life.

Pricing is usually based on the type of wood, the number of pieces used in the pallet design, and the total amount of wood measured in board feet, which takes into account the thickness of the individual boards.

The other major factor to consider is the pallet's construction. Quality nails usually produce much stronger pallets than common staples. Care must also be taken with major knots or splits found in the wood, especially on end boards. Nails should not be placed in splits.

Unless damaged, wood can be used over and over again. Consider recovered and recycled pallets. Just make sure you inspect them before receipt.

Most importantly, work with your supplier and explain your needs.

"Let them know what you can live with and what you do not want," says Bush.