"Export packing: seaworthy" is the most common packing clause in aluminum purchasing, and it means nothing you can inspect.
Ask three suppliers what seaworthy packing includes and you get three answers: one means a wooden crate, one means PE film and edge boards, one means "whatever we normally do". All three are honest. None of them is a specification.
A packing specification is not a description of intent. It is a list of things an inspector can look at and mark pass or fail. Here is how to write one.
Five things every packing spec has to define
The unit. Is the material shipped as a bundle, a pallet, a single coil, a crate, or loose sheets? Bands per bundle, weight per bundle, maximum stack height. Without this, the rest of the spec has nothing to attach to.
The material in contact with the metal. PE film, VCI film, paper interleaf, cardboard, wood, or nothing. Contact material matters because aluminum scratches against harder particles and stains against moisture, and both failures start at the interface.
The restraint. Steel strap, plastic strap, both, and at what spacing. A 3-tonne bundle held by two straps will move. A coil with no radial strap will breathe.
The moisture control. Desiccant, VCI, barrier bag, or none. This is the clause most often omitted and the one that decides whether a claim happens in a winter crossing.
The marking. Shipping marks, heat number, bundle number, gross and net weight, handling symbols. Marking is how the certificate connects to the bundle at the destination — if the marks do not match the documents, the whole traceability chain has a gap in it.
The layer structure that makes a spec usable
Packing specs that fail are usually written as a paragraph. Packing specs that work are written in three layers, because the three layers fail for different reasons.
Layer 1 — surface protection. What touches the metal. Interleaf, film, paper. Failure here is cosmetic and irreversible: a scratch found at destination cannot be polished out of an anodizing-grade sheet.
Layer 2 — mechanical protection. Edges, corners, faces. Edge protectors, corner boards, end caps, top and bottom covers. Failure here is denting and deformation, usually from handling rather than from the sea.
Layer 3 — unit stability. Strapping, banding, blocking, bracing, saddles. Failure here is a shifted load, which turns into layers 1 and 2 damage in transit.
Write the spec so each layer has its own line. When something goes wrong you will know which layer failed, and so will the surveyor.
The wood problem nobody plans for
Almost every aluminum packing spec includes timber: bearers under a bundle, a crate around plate, a saddle under a coil, chocks against the container wall.
Solid wood packaging crossing a border is regulated. Under ISPM 15 — the international phytosanitary standard for wood packaging material — solid wood used to support or contain goods must be either heat treated or fumigated, and marked with the IPPC stamp showing the treatment and the country code.
The exemptions matter, because they are where cost can be saved legally. Processed wood is exempt: plywood, particle board, oriented strand board, and veneer are not considered raw wood packaging. So a plywood crate is simpler to export than a timber crate of the same strength, and a plywood pallet avoids the treatment step entirely.
Three practical consequences.
Unmarked timber is a customs problem, not a supplier problem. If a container is inspected on arrival and the bearers carry no IPPC mark, the material can be held, treated at destination, or returned. The cost lands on whoever is the importer of record — which is you.
Heat treatment is not the same as kiln drying. Kiln-dried timber is dry; heat-treated timber has been through a schedule that kills pests. A supplier saying "our wood is kiln dried" has answered a different question.
The mark has to be legible. A stamp applied under a steel strap and then compressed is not a mark. Say in the specification that the stamp must be visible on inspection.
Write it as one line: All solid wood packaging to be ISPM 15 compliant and IPPC marked; plywood preferred where strength permits.
What changes between transport modes
Sea freight is the demanding case. Six weeks, four climate zones, condensed moisture, and vibration that works straps loose. Everything above applies, and desiccant is not optional.
Air freight is fast and dry, and the risk moves to handling: many small touch points, tight schedules, and loading equipment that does not care about edges. Protection here is about crush and impact, not moisture.
Road and rail add vibration without the moisture. Strapping and blocking matter most; desiccant usually does not.
If a specification is written for one mode and used for another, the failure will be in the layer that mode stressed. A sea spec applied to air freight is over-specified and expensive. The reverse is a claim.
Four clauses that are usually missing
"Interleaved with paper, 40 g/m² minimum." "Interleaved" alone does not say with what or how thick. Newspaper is not interleaf, and a supplier out of paper stock will use whatever is at hand.
"Strapping at maximum 600 mm pitch, with corner protection at every strap." Strap without corner protection cuts the edge. Strap spacing without a number is not a spec.
"Desiccant: 1 kg per cubic metre of packed volume, minimum, sized for a 45-day voyage." Desiccant quantity has to be a number tied to a volume and a duration, or it will be one small bag by the door.
"Loading photographs: container interior before doors close, showing packing, strapping and desiccant in place." This is the clause that makes the other three enforceable. Without it, every packing dispute becomes a memory contest.
Who pays, and how it shows up in the price
Packing is quoted inside the price per tonne, not as a line item, so the difference between a minimal and a proper specification is invisible until you compare two quotes and wonder why one is higher.
The honest way to handle it is to ask for the packing cost separately on a first order. Most mills will break it out if asked, because it is a real cost they are carrying: film, interleaf paper, edge boards, desiccant and the labour to apply them are all per-tonne expenses, and the desiccant alone scales with voyage length.
Two commercial notes worth knowing.
Packing cost is largely fixed per tonne, so on a small order it is a larger share of the price. This is one reason a 5-tonne order is disproportionately expensive — it is not only the production setup.
Packing improvements are cheap before production and impossible after. Adding interleaf to an order that is already rolled and bundled means unbundling and rebundling, which costs more than the interleaf ever would have.
How to inspect packing before the container closes
You are not going to be at the mill. The specification has to do the inspecting for you, through photographs and a checklist.
Ask for these five, in this order:
- Bundle or coil as packed, before loading — shows the layer structure
- Strap and edge protection close-up — shows whether corner boards are actually there
- Desiccant in place, with quantity visible — a photo of a sealed bag proves nothing
- Container floor before loading — clean and dry, or not
- Container interior, doors open, fully loaded — shows blocking and bracing
Five photographs, taken at defined moments, are a better record than a page of prose. Put the requirement in the order, with the number of photographs and what each must show. Suppliers take the photos when the order asks for them; nobody takes them when it does not.
The template
Packing specification — aluminum sheet and coil, sea freight
Unit: Sheet bundles, max 3 t per bundle, max 4 bundles high
Layer 1: PE film outer wrap; paper interleaf 40 g/m2 min between sheets
Layer 2: Edge protectors on all four long edges; corner boards at strap points
Layer 3: Steel strap, 600 mm max pitch; radial strap through coil eye
Moisture: Desiccant 1 kg/m3 packed volume, sized for 45-day voyage
Coil: Eye-to-sky, wooden saddle matched to diameter, chocks to floor
Marking: Bundle no., heat no., size, gross/net weight, handling symbols
Evidence: 5 loading photographs as listed; sent before vessel departure
That is one page. It fits in a quotation, it can be attached to a purchase order, and every line can be checked against a photograph.
Where this connects to the rest
Packing is the last specification you write and the first one you regret. If a shipment has already gone wrong, our note on why aluminum arrives damaged covers the four failure patterns and the photo sequence that keeps a claim alive — useful if you are dealing with a container that is already at sea.
If you are writing a packing specification for a new route or a new product form and want it checked against what a mill can actually execute, send it over. The clause that most often needs adjusting is desiccant quantity, because it is usually sized for a container rather than for a voyage.