Don’t panic. Stains on pallets are usually not a concern. Find out why and how stains happen.
- water soluble extractives
With the exception of the water soluble extractives, these components are relatively stable when using wood for pallets.
Except for oak, most wood species used in pallets have a low level of extractives. Oak is one of the strongest and most durable of the pallet materials. Unfortunately, oak also has some of the highest levels of these water soluble extractives.
When oak comes into contact with metals like steel - and moisture is present - these extractives can react to create blue or black stains. Staining does not cause performance loss but it can be an issue with products sensitive to discoloration.
Any of these metal contacts will create the stains:
- All wood pallets have nails.
- Some are secured with steel banding.
- Some products are even uncoated steel.
For international shipments staining can become even worse. Required heat treating brings large amounts of moisture to the surface of the pallet.
- Request dried pallets or used pallets. Without moisture, the staining process is less likely to occur - even with oak.
- Use a slip sheet or other moisture barrier to protect your products from the stain.
- Request hardwood pallets without oak. Since many pallet customers want oak, it may be possible to have your pallet supplier segregate out the oak and give you other hardwood species less likely to stain.
- Request plywood or other panel pallets.
- Request softwood pallets - they don’t have the same staining potential.
- Request plastic or other non-wood pallets.
Post by: John Clarke, Technical Director