A container crossing the ocean is a rust machine: temperature swings from deck heat to night cold cause condensation cycles — “container rain” — that soak everything inside twice a day. Parts that left your dock gleaming arrive at the customer with orange bloom, and the claim lands on your desk. Here is how to pack metal for transit so that does not happen.
Why shipments rust
Three culprits: condensation from temperature cycling, salt air on ocean routes, and packaging that holds moisture against the metal (plain cardboard and untreated kraft paper are the worst offenders — both are mildly acidic and hygroscopic). Desiccant bags alone rarely survive a 4–6 week transit: they saturate early and stop working.
The layered approach that works
Layer 1 — contact protection. Wrap or interleave parts with VCI paper (Cortec VpCI-146). It protects the surfaces it touches and cushions machined finishes.
Layer 2 — sealed VCI enclosure. Bag or line the crate with VpCI-126 film or gusseted liners and seal it — heat seal or fold-and-tape. The sealed film creates a protected micro-atmosphere: corrosion inhibitors inside, humid salt air outside. Sealed VpCI-126 protects up to 2 years, far beyond any transit and the storage that follows.
Layer 3 — for bare high-value surfaces. Spray or dip critical surfaces with a liquid VpCI rust preventative before wrapping. Modern water-based films dry clean and do not need removal at destination.
Practical rules from the loading dock
Pack parts dry and at room temperature — never bag a part that came off a washer an hour ago unless it is fully dry. Keep bare hands off machined surfaces; fingerprints are salt deposits. Do not mix VCI packaging with plain cardboard touching the metal. Seal the VCI bag properly — an open bag is a slow bag. And label the packaging so the customer knows parts are VCI-protected and re-seals what they do not use.
What it costs vs. what a claim costs
VCI packaging typically adds cents to a few dollars per part. One rejected export shipment — freight both ways, rework, the customer relationship — costs thousands. This is the cheapest insurance on the packing list.
Shipping metal parts domestically or overseas?
Tell us the part, the route, and the transit time — we will spec a Cortec VCI packaging system sized to your parts, with carton and volume pricing.