Cold storage customers ask us for the same thing every year and describe it differently every time: pallets that do not sweat, do not frost, and do not turn into a slip hazard on the way out of the freezer.
What they are actually asking for is dry wood, and the reasons are worth understanding because the failure mode is not obvious.
Moisture does not leave a freezer
Wood dries by evaporation, and evaporation essentially stops at freezing temperatures. A pallet at 22% moisture that goes into a −18 °C freezer is still at 22% moisture when it comes out three weeks later.
In a warm, dry warehouse that same pallet would have shed several points over the same period. In cold storage, nothing happens. The moisture is locked in place, and if it was above the threshold on entry it will be above the threshold on exit.
Which means the moisture specification for cold chain has to be tighter than for general distribution, because there is no drying to fall back on.
The meter lies when it is cold
Pin-type moisture meters measure electrical resistance between two pins, and the resistance of wood changes with temperature as well as with moisture. On frozen wood, the reading comes out low — frequently several percentage points low.
So a pallet that reads 16% straight off a refrigerated trailer in January may genuinely be at 21% once it has come up to room temperature. We have watched buyers accept loads on cold readings and then find mould a fortnight later.
Our rule is straightforward: nothing gets a moisture reading until it has been in the yard at ambient temperature for at least four hours. It slows down winter receiving and it is not negotiable.
Frost, condensation and the slip hazard
A pallet coming out of a freezer into a warm loading area is below the dew point of the surrounding air. Water condenses on it immediately, and on a smooth deck that produces a genuinely dangerous surface for anyone walking on the load or handling it.
Going the other way, a warm damp pallet entering a freezer frosts up, and the frost gets between the load and the deck. When the unit comes back out, that frost melts into the product.
Neither problem is solvable at the pallet. They are handled with staging: an intermediate temperature zone, or simply enough dwell time in a dock area for the temperature to equalise before the load moves on.
What we send to cold chain customers
- Grade A only — cold storage racking is unforgiving and the load cases are demanding.
- Dispatched at the dry end of our range rather than simply under 19%.
- Stored under cover and staged indoors before dispatch, never straight from an outdoor row.
- Sorted for staining and odour, because cold chain is almost always food.
- Where the specification requires wash-down or a documented material history, we recommend plastic and say so.
The plastic question, honestly
Cold chain is one of the applications where plastic has a real case. It does not absorb moisture, it does not frost the same way, and it can be washed.
The counter-argument is the usual one: plastic only pays in a genuinely closed loop, and cold chain distribution frequently is not one. A plastic pallet that leaves on a delivery and does not come back cost you $60 to move one load.
Measure your loss rate before you decide. It is the variable that settles this question and almost nobody has it.