Guide / Moisture
Moisture, mould and what to do about both
Mould needs moisture, and wood with a moisture content below 20% will not support mould, mildew, decay or fungus. Check a pallet by weight, smell and colour, and treat anything wet as a different grade.
Moisture content in one paragraph
Moisture content (MC) is how wet the wood is, as a share of its dry weight. Kiln-dried and well-kept pallets sit well below 20%. A pallet left on soil through a wet spring can sit far above it. Above 20% mould and decay become possible; the higher it goes and the warmer it is, the faster they set in.
Reading a pallet by eye and hand
| Sign | Likely meaning | What to do |
|---|---|---|
| Grey, silvery boards | Weathered; may be dry underneath | Check weight; usually fine for non-food freight |
| Dark patches, musty smell | Active mould or decay | Keep out of food-adjacent freight |
| Heavy for its size | Holding water | Let it dry before loading, off the ground and ventilated |
| Soft corners, crumbling | Rot | Core or grind |
A meter reads moisture content directly; if you do not have one, weight and smell are the next best signs. A standard 48 x 40 weighs about 33 to 48 pounds dry, so one that feels like a sandbag is wet.
Why heat treatment is not a fix
Heat treatment kills pests, not mould spores. A heat-treated pallet loaded into a trailer van while still hot can grow mould. Let treated stock cool and dry before the doors close, and move air through stacks; even a slight breeze of a few feet per second helps.
Oklahoma timing
The risky window in Oklahoma City is April through June, when monthly rain runs from about 3.6 to 5.3 inches. A pile cleared in March avoids the worst. The storm-season guide has the month-by-month table.
A simple field test
A pallet feels heavy for its size when wet, and the grey or black staining on boards, a musty smell and soft spots under a screwdriver all signal trouble. Moisture meters give a number, and below twenty percent mould will not grow. If you have no meter, look at the stack after a week of dry weather; boards that still look dark are probably holding water.
Questions, answered
Can moldy pallets be sold?
Yes, as cores. Say in the request that the pile is wet or mouldy; it will be read as a recycling or grinding load, not as stock.