Frequently Asked Questions


Frequently Asked Questions


General Wood Properties

How much water is in wood?

There are two important types of water are in the wood. So called Bound Water is located in the cell wall of the fibers while Free Water is located in the lumen (cell opening). The important moisture content to remember is approximately 28% which is the fiber saturation point. Bellow the fiber saturation point the wood only contain bound water while above the fiber saturation point wood has both bound and free water. When the wood is harvested its moisture content is about 70-120%. During the initial portion of drying wood mainly loses free water until the fiber saturation point is reached. This process is a rapid process; therefore, does not require a lot of energy. The properties of wood does not influence by the free water that is why the strength of the wood and the specific gravity does not change beyond the fiber saturation point. All wood which has a moisture content above fiber saturation point are called Green Wood. We tend to call a piece of wood dry if it is at 19% or less moisture content. Wood used indoors will eventually stabilize at 8-14% moisture content; outdoors at 12-18%. The strength of the wood increases greatly bellow the fiber saturation point which makes the dry pallets more valuable for the customers.



Why is fiber saturation moisture level so important?

The physical and mechanical properties of wood change only when wood dries below the Fiber Saturation Point (FSP). Shrinkage only occurs below FSP. Pallets made of wood with a maximum Moisture Content (MC) less than FSP will not contaminate most products that are moisture sensitive.



What is green wood?

Wood is called green when the MC level is equal to or greater than FSP. The MC of wood in a tree varies somewhat throughout the stem, but typically varies 50 to 100%, depending on the wood species and season of the year. A typical average MC for wood living in a tree is 70%.


What moisture content does wood need to be to prevent mold growth?

Wood with moisture content below 20% will not support mold, mildew, or decay fungal attack.



Pallet Properties and Performance

How can I make my pallets be rendered fire retardant and flame spread resistant?

Purchase fire retardant, pressure treated lumber, and manufacture the pallets from this material. Or, apply a fire retardant coating to pallet parts.



What wood species are used to make wood pallets?

Oak, Elm, Maple, Beech, Hickories, Ash, Sweetgum, Black Tupelo, Aspen, Yellow-Poplar, Firs, Spruces, Southern Pines.



How much water is in wood?

There are two important types of water are in the wood. So called Bound Water is located in the cell wall of the fibers while Free Water is located in the lumen (cell opening). The important moisture content to remember is approximately 28% which is the fiber saturation point. Bellow the fiber saturation point the wood only contain bound water while above the fiber saturation point wood has both bound and free water. When the wood is harvested its moisture content is about 70-120%. During the initial portion of drying wood mainly loses free water until the fiber saturation point is reached. This process is a rapid process; therefore, does not require a lot of energy. The properties of wood does not influence by the free water that is why the strength of the wood and the specific gravity does not change beyond the fiber saturation point. All wood which has a moisture content above fiber saturation point are called Green Wood. We tend to call a piece of wood dry if it is at 19% or less moisture content. Wood used indoors will eventually stabilize at 8-14% moisture content; outdoors at 12-18%. The strength of the wood increases greatly bellow the fiber saturation point which makes the dry pallets more valuable for the customers.



What is the best way to dry hardwood pallets?

Pallets dry fastest in spring and summer in temperate climates. When air-drying pallet parts or pallets, the top of the piles should be covered to protect pallet components from direct exposure from the sun. Direct exposure to sun will result in excessively rapid drying and the exposed lumber will warp, split, and check to the point the pallets may not be useful. Orient the stickers, or in the case of stacked stringer pallets, stringers parallel to the predominant wind direction. If a fan is used, drying time is cut by 2/3, and if the pallets are dried in a kiln operating at 100 to 110°F, deckboard moisture content change of 85% to 20% could be achieved in about 5 days.



How do I rid of insects in wood pallets?

Green wood in pallets can be heat sterilized at 133°F for 3 to 5 hours exposure. Wood pallets can be fumigated by Pest Control Operators (PCOs) using Methyl Bromide. Another effective chemical treatment is the use of powder fumigators, which can be found in grocery stores and hardware stores. Place two cans of the fumigator container in a closed van to rid of insets for 4-6 hours. For long-term efficacy, topical applications such as Borate Salts or Copper-8-Quinolinolate. Pallets could also be painted to prevent re-infestations.



How do I prevent Mold growth on Pallets?

Periodically apply bleach solution to the lumber and remove any nearby sources of mold spores (such as decaying wood). Good housekeeping can reduce the amount of spores in the air, which ultimately reduces mildew growth. It is also important to keep the wood dry so the moisture level remains below 20%. You can also apply fungicide. The most popular fungicides used on wood to control mold contain copper-8-quinolinolate or chlorothalonil.



Does mold affects the strength or stiffness of my pallet?

No, mold is only a surface phenomenon and it does not cause any structural damage in the wood pallet. Although, it could contaminate products on the top of the pallet; therefore, mold prevention is really important.



How do I rid of mold on pallets?

One treatment to kill or remove mold and mildew from lumber is to spray or dip in the following solution:

  • 1/3 part household detergent
  • 2 part water
  • This treatment is effective for 3-5 days.

  • How do I prevent decay of wood pallets?

    1. Eliminate moisture 2. Poison the food source (possible with safe fungicides) If food contact is not an issue, construct a pallet with any of the salt or water-borne commercial pressure impregnated lumbers. These pressure-treated products are typically southern pine.



    How do I eliminate odor contamination of products?

    Deodorants, such as “ODO-BAN” can be sprayed on pallets. These deodorants are available in concentrated form from retail outlets such as Sam’s Club.



    Does shrinkage reduce load carrying capacity?

    No. Shrinkage does not imply a reduction in load carrying capacity of pallet parts. However, shrinkage will loosen joints and cause splitting, both of which tend to influence pallet strength, stiffness, and durability.



    How do I reduce the number of end splits?

    End splits occur in the drying of green wood. You can apply end coatings to reduce the number of end splits.



    How much will wood pallet parts shrink as they dry?

    The percent shrinkage depends on the species of wood. To roughly estimate how much wood pallet parts will shrink when air-dried to 18%, multiply the green part size by 0.02 or 2% and at long-term equilibrium in warehouses by 0.04 or 4%. This is equivalent to a 1% shrinkage/5% MC change below fiber saturation point.



    How do I know how heavy a wood pallet is?

    The weight of the wood pallet will depend on the volume of lumber used in the pallet, the specific gravity of the wood, and the MC of the wood.



    Will the bacteria in wood affect its strength?

    No. The bacteria in wood will not affect its strength or stiffness.



    How do I prevent pallets from causing corrosion of metal products?

    1. Select wood species that have water-soluble pH values greater than 5.2 (Ash, Maple, Hickory, Yellow-polar, Sweetgum, or Tupelo)
    2. Use dry lumber or dry the pallet to less than 20% moisture. The pallets must be kept dry during use
    3. Seal the product in a moisture barrier or plastic film

What is iron stain?

Iron stain is dark blue or black and is often confused with mold. It can rub off onto the products or packaging set on top of the pallet until the pallet dries.



How do I know my pallets are durable?

Stronger, stiffer, and denser hardwoods will result in more durable pallets. The FasTrack simulation developed based on the supply chain of Proctor&Gamble can be used to evaluate the durability of the pallet design. For more information please visit the following link

FasTrack Protocol


How do I test the strength and stiffness of pallets?

ASTM D1185 – Standard Test Methods for Pallets and Related Structures Employed in Materials Handling and Shipping is mainly used in the United States. The protocol uses the airbag to apply load on the pallets which represents the worst case among the loading conditions. ISO 8611 – Pallets for Material Handling – Flat pallets is the internationally accepted standard to test pallets. It has three parts. Part 1 provides information about the test setup, Part 2 provides information about the deflection limits, while Part 3 provides information on the evaluation of the pallet using the actual payload. ISO 8611 uses a combination of rigid bars to apply the load to the pallet.


How do I prevent iron stain?

Iron stain treatments, which rid of discoloration when applied to wood, are available. Also, reduce the amount of oak and hickory when assembling a pallet. (Iron stain is most common when using oak and hickory).


Transportation Issues: Container, Fumigation and Heat Questions



Does the load carrying capacity of the pallet depends on the type of load?

Yes, the load carrying capacity of the pallet highly related to the type of load that is carried by the pallet. The type load can increase the load carrying capacity of the pallet as much as 60-70%. The rule of thumb is that if the pallet is less stiff the stiffness of the load makes more difference then if the pallet is stiffer. Some preliminary information can be found in ISO 8611 – Part 3 or at the following link.



How do I prevent water contamination during export in containers?

1. To prevent water contamination during export, allow KD 19% lumber to dry to 10 to 12% to protect the contents of containers.

2. Use desiccant bags in the container to capture the excess moisture.



How do I fumigate wood pallets?

1. Generally, commercial pest control operators perform the fumigation. However, pallet manufacturers can become certified fumigators. Training and certification is available through state departments of agriculture.

2. Fore more information please visit the following link:

Pallet Enterprise Website


How long do I need to heat-treat a pallet?

Heat-treating times depend on the equipment, the pallet design, and the moisture content of the pallet parts. It approximately takes 2.5 hours for KD softwoods; 4.5 hours for green hardwoods, and 2.5 hr. for recycled lumber.


Important Regulations


What criteria are important for “Installation of Sprinkler Systems” by the National Fire Protection Association?

Commodity class of the product (how much of a fire hazard is your product) and occupancy classification (type of business, height of building, number of offices, warehouses, etc.)


What are the International Phytosanitation Regulations?

They are guidelines for regulating wood packaging material in international trade. The US and most of its trading partners have adopted these standards as a regulation with some modification. These regulations require raw wood packaging, pallets, dunnage, blocking and bracing to be heat-treated or fumigated. Visit the following link for more information: http://www.aphis.usda.gov/import_export/plants/plant_exports/wpm/


Do pallets comply with CONEG heavy metal limits in packaging?

Yes. Although there are some metals restricted by CONEG, neither wood nor the low carbon steel nails used in pallet assembly contains regulated metals.


Do I need to use special design parameters if the pallets will be used in an automated material handling system?

Yes, pallets used in an automated material handling system need to meet a more strict requirement system created by ANSI MH1 committee. The requirements can be found in the Section 10 of ANSI MH1 standard.


The standard can be downloaded for free from:

http://www.mhi.org/media/news/8990


For more information please visit our website: