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Technical questions go straight to the graders.
The wood has opinions, and they are mostly about stiffness and water.
Almost every pallet in the eastern United States is built from southern yellow pine or a mixed bag of Appalachian hardwoods. Buyers assume hardwood is the premium option; it is more accurate to say they are different tools. Pine is lighter — which is payload on a weight-limited lane — cheaper, more uniform and perfectly stable once dried. Hardwood is stiffer, holds a nail far better, and survives more handling cycles.
The mistake people make when comparing them is attributing to the species what belongs to the drawing. Hardwood platforms are frequently heavier because they were built to a heavier specification in the first place: thicker boards, four stringers, seven bottom boards. If you are evaluating two samples, write down the board dimensions before you say a word about oak versus pine.
Water is the other half of this subject. Moisture content is quoted against oven-dry weight, which is why green softwood can exceed 100%. Nineteen percent is the number everyone cites because mould needs free water in the cell and that requires roughly 20%. But wood moves toward equilibrium with wherever it lives, so drying is a starting condition rather than a permanent state — and reclaimed stock, having cycled for years, is usually the most stable material available.
- Pine for weight-limited and one-way lanes; hardwood for racked spans and high-cycle closed loops.
- Compare board dimensions before comparing species. Most weight differences belong to the spec.
- Moisture content is a percentage of oven-dry weight, not total weight.
- 19% is the mould threshold with a margin, not a stability target. Millwork wants 8–12%.
- Reclaimed wood is usually drier and more dimensionally stable than new green lumber.
- Specifying hardwood for a one-way export shipment that will never come back
- Expecting a heat-treated platform to be dry — HT is phytosanitary, not a moisture spec
- Specifying a moisture content without saying how it will be measured
- Insisting on species purity in recycled stock, which is an expensive specification by accident
- Storing kiln-dried stock outdoors and being surprised when it regains moisture
2 on materials, newest first.
Moisture content, explained with a bathroom scale
Nineteen percent is the number everyone quotes. Here is what it is a percentage of, why it is counter-intuitive, and how to check it yourself.4 min · 899 words · Jonah, millwork
March 12, 2024Southern yellow pine versus Appalachian hardwood
Two species groups, two different jobs. One is lighter and cheaper; the other is stiffer and holds a nail better. The choice is not about quality.4 min · 822 words · Jonah, millwork
The tables behind these posts.
The same data we work from in the yard, so you can check the arguments above against the numbers.
| Species | Group | Specific gravity | Stiffness | Nail holding | Weight | Cost | Note |
|---|---|---|---|---|---|---|---|
| Southern yellow pine | Softwood | 0.51 (oven-dry sg) | Moderate | Moderate | Light | $ | Plantation-grown, abundant, dimensionally stable once dried. The default for new builds. |
| Appalachian red oak | Hardwood | 0.63 | High | Excellent | Heavy | $$$ | Stiffest common option. Best for racked spans and high-cycle closed loops. |
| Poplar / tulipwood | Hardwood | 0.42 | Moderate | Good | Light-medium | $$ | Light for a hardwood, clean-looking, favoured on the millwork bench. |
| Maple (soft) | Hardwood | 0.54 | High | Very good | Medium-heavy | $$ | Common in mixed Appalachian loads; good all-rounder. |
| Sweetgum | Hardwood | 0.52 | Moderate | Good | Medium | $ | Prone to warping if dried badly. Fine in a repaired platform, awkward in millwork. |
| Mixed Appalachian | Hardwood | 0.42–0.63 | Variable | Good–excellent | Medium-heavy | $$ | What a recycled hardwood load actually is. Strong, heavy, and genuinely inconsistent. |
A recycled load is a mix by definition, because the recovered pool is a mix. We sort to a single species group on request, which costs more and takes longer.
| Type | Withdrawal resistance | Drive speed | Typical use | Note |
|---|---|---|---|---|
| Smooth shank | Low | Fastest | One-way economy platforms | Loosens over repeated cycles. Acceptable where the platform will not return. |
| Helical / screw shank | Good | Moderate | Hardwood assembly | Twists as it drives, cutting a thread. Strong in dense species. |
| Stem threaded (annular ring) | Excellent | Moderate | All our repairs, durable builds | Rings bite against withdrawal. The industry workhorse and our default. |
| Staple | Low–moderate | Very fast | Collars, light assembly | Fine for non-structural joints. Not used on deck-to-stringer joints here. |
| Steel plate, through-nailed | Highest | Slow | Stringer break repair | Strongest repair available. Check conveyor clearance before specifying. |
One line in a specification — “stem-threaded fasteners, staggered pattern, driven flush, no protrusion” — is the difference between a platform that lasts two years and one that lasts five. The long version.
| State | Moisture content | Mould risk | Note |
|---|---|---|---|
| Green, off the saw | 60–120%+ | Very high | Heavy, moves as it dries, blooms readily. Rarely what you want. |
| Air dried, yard stored | 15–22% | Moderate | Typical of outdoor recycled stock in a humid month. |
| Kiln dried | ≤19% | Low | Below the biological threshold for mould. The usual specification. |
| Kiln dried, millwork grade | 8–12% | Very low | For cladding and interior work, matched to heated-interior equilibrium. |
| Reclaimed, long service | 10–16% | Low | Years of cycling beat any kiln schedule for stability. An under-appreciated advantage. |
Moisture content is water weight divided by oven-dry weight, which is why green softwood can exceed 100%. Heat treatment is not kiln drying — see moisture explained.
The terms these posts assume you know.
Vocabulary is the cheapest performance upgrade in this industry — almost every argument we have with a new customer comes down to two people using the same word for different objects.
- Board foot
- A unit of lumber volume: 12 × 12 × 1 inches. A 48×40 GMA pallet contains roughly 35–40 board feet.
- Core
- An unsorted, un-repaired used pallet — raw material for a recycler. Sold by the load.
- HT
- Heat treated: wood core held at 56 °C for 30 continuous minutes to satisfy ISPM-15.
- KD
- Kiln dried — moisture reduced, usually to ≤19%, to prevent mould and dimensional movement.
- Whitewood
- Any non-pooled, non-rental pallet — owned outright rather than leased from a programme.
Where materials meets what we actually sell.
Materials questions we get.
Should I specify hardwood or softwood?
Softwood for weight-limited lanes, light product and one-way shipments. Hardwood for racked storage, unsupported spans, dense product and closed loops where the same platform comes back thirty times. A recycled load is a mix by default because the recovered pool is a mix; we sort to one group on request, at a premium and a longer lead time.
How do I check moisture content myself?
Cut a sample from the middle of a board, weigh it, dry it in an oven at its lowest setting overnight, weigh it again. Wet minus dry, divided by dry, times a hundred. A pin meter is faster and adequate for yard work but reads the surface and is species-dependent; for a dispute, do the oven test.
Why is recycled wood more stable than new?
Because it has already done its moving. Years in service, with repeated wetting and drying, bring wood to a stable equilibrium far more thoroughly than any kiln schedule. New green-lumber pallets delivered into a humid plant cause more mould problems than reclaimed stock does, which surprises people every time.
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