The freezer problem: pallets below zero

Cold makes wood brittle, not weak

Wood actually gains a little static strength as temperature falls — the cell walls stiffen. What it loses is toughness: the ability to absorb a sudden impact by deforming instead of fracturing. In a freezer, a fork tine that would have bruised a deck board at 70°F will split it at -10°F.

This is why cold-chain breakage patterns look different. You see split lead boards, cracked stringer ends and shattered bottom boards — impact damage — rather than the progressive sagging you see in ambient racking. Operators often conclude the supplier changed something. Nothing changed except the thermometer.

The moisture cycle is the real killer

A pallet moving from a humid loading dock into a freezer condenses moisture on its surface, and that moisture then freezes. Repeat this daily and water is driven into the grain, where each freeze expands it. The result is splitting along the grain that has nothing to do with load and everything to do with thermodynamics.

• Start dry: specify below 19% moisture content on delivery, and ideally below 15% for cold chain
• Minimise dwell time on a humid dock — staging pallets outside a freezer door is the worst possible place for them
• Avoid outdoor staging entirely; a rained-on pallet entering a freezer is a split pallet
• Rotate stock so no individual pallet cycles more than necessary
• Consider plastic on genuinely closed freezer loops, where washdown and non-absorbency both help

Specifying for cold

Plastic is genuinely competitive in cold chain — one of the few applications where we say so plainly. The condition is that the pallet must reliably return. On a one-way frozen export lane, plastic is an expensive gift.

Setting the expectation

Cold chain consumes pallets faster than ambient storage, typically by a meaningful margin, and this is worth putting in the budget rather than discovering in the variance report. The operations that handle it well do three things: they buy dry, they minimise dock dwell, and they treat a higher replacement rate as a known cost of the environment rather than as evidence that somebody sold them a bad lot.

Appendix: the data behind this

Every piece on this site closes with the slice of our operating record that bears on what it argues. The full record is published at /resources/operating-record.

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