Heat-Treated Pallets: Why They Matter and How They're Made
Heat treatment is the gold standard for international shipping pallets. Here's what happens inside the kiln.
If you've ever shipped goods internationally, you've probably encountered the requirement for heat-treated (HT) pallets. But what exactly is heat treatment, why is it required, and how does it work?
Why Heat Treatment?
Raw wood can harbor insects, larvae, and fungal organisms. When untreated wood packaging travels across borders, these pests can too — potentially introducing invasive species that devastate local ecosystems. The emerald ash borer, one of the most destructive invasive insects in North America, is believed to have arrived via untreated wood packaging from Asia.
Heat treatment eliminates these biological risks by raising the wood's core temperature high enough to kill any organisms living in or on the material.
The Process
Heat treatment follows a precise protocol:
Loading: Pallets are stacked inside an industrial kiln or heat treatment chamber
Heating: The chamber temperature is raised until the core temperature of the wood reaches 56°C (132.8°F)
Holding: This core temperature must be maintained for a minimum of 30 continuous minutes
Monitoring: Thermal probes inserted into the wood verify that the core reaches and holds the required temperature
Cooling: Pallets are removed and allowed to cool naturally
Stamping: Each treated pallet is stamped with the IPPC mark indicating HT treatment, the country code, and the facility number
The IPPC Stamp
The stamp is the proof of treatment. It includes:
The IPPC wheat sheaf logo
A two-letter country code (US, CA, MX, etc.)
The treatment provider's assigned number
The treatment code: HT (heat treated) or MB (methyl bromide, which is being phased out)
Without this stamp, wood packaging is not accepted for international trade by most countries.
Does Heat Treatment Affect the Wood?
Heat treatment doesn't significantly change the wood's mechanical properties for pallet use. The temperatures involved are well below what would damage the fiber structure. Some benefits actually emerge:
Reduced moisture content, which makes pallets lighter and more resistant to mold
Elimination of pest risk without chemicals
The wood may develop a slightly darker color, which is purely cosmetic
Used Heat-Treated Pallets
Heat treatment is a one-time process — once treated, the pallet retains its status as long as it hasn't been repaired with untreated wood. When buying used pallets for export, verify that the IPPC stamp is present, legible, and that any repaired boards also bear treatment marks.
At Stockton Pallet Co., we maintain inventory of heat-treated pallets specifically for customers with export needs. Every HT pallet in our inventory has been verified for stamp integrity before being offered for sale.
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