📅 04 September 2026 ·
🕐 11 min read ·
📍 SVC Group, Vietnam
26°C
Dew point at HCMC loading
30°C air at 80% RH
48h
Mould onset in humid container
Once condensation starts
0.1–0.3%
Desiccant cost vs cargo value
Against 10–100% loss risk
28d
HCMC to North Europe
Four weeks of exposure
A container of cashew kernels leaves Dong Nai at 30°C. Four weeks later it is opened in Rotterdam in December at 5°C. Between those two moments, nobody looks inside.
Most of the time nothing happens. Occasionally, the buyer opens the doors to find water stains down the carton walls, a musty smell, and a claim to file. The difference between those two outcomes is almost never luck. It is decided in the ninety minutes before the container doors were sealed.
This article covers what actually happens during container loading at a cashew factory, the physics of what goes wrong in transit, and the specific checks that separate a container that arrives clean from one that does not.
🌿 Why cashew specifically
Four Properties That Make Cashew Kernels Vulnerable In Transit
Cashew is not a forgiving cargo. Four characteristics compound each other over a long ocean voyage:
💧
Hygroscopic At Low Moisture
Export kernels leave the factory at 3.5–5.0% moisture. That is a deliberately dry state, and dry material actively pulls moisture from surrounding air. A kernel that absorbs its way to 6–7% is a kernel at real mould risk
🧤
High Oil Content
Cashew kernels are roughly 45–48% fat. Heat accelerates oxidation and rancidity. A container sitting on a tropical quay for a week before loading onto the vessel is accumulating damage that only shows up as off-flavour at destination
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Packaging Absorbs Even When Product Does Not
Vacuum bags protect the kernel. Cartons and pallets do not protect themselves. Corrugated board absorbs moisture readily, loses compression strength, and a stack that was stable on loading can collapse by arrival
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Worst-Case Route Profile
Tropical origin to temperate destination is the highest-risk condensation profile there is. Vietnam to Northern Europe or the US East Coast in winter crosses the largest temperature differential in global trade
🌡️ The physics
Container Rain And Cargo Sweat Are Two Different Problems
These terms get used interchangeably. They describe different phenomena with different causes, and knowing which one you are looking at determines how you prevent it.
Two distinct condensation mechanisms — prevention differs for each
Container rain
The container is sealed in Ho Chi Minh City with warm, humid air inside. As the vessel moves north, the steel shell cools. When the shell drops below the dew point of the trapped air, moisture condenses on the roof and upper walls, then drips down onto the top layer of cargo.
The maths is not abstract. Air at 30°C and 80% relative humidity — an ordinary loading morning in Dong Nai — has a dew point around 26°C. Every hour the container skin sits below 26°C, condensation is forming. On a route to Northern Europe in winter, that is most of the voyage.
Cargo sweat
The reverse situation. Cargo that has been chilled — on a cold leg of a voyage, or in cold storage — is exposed to warmer, more humid air, typically when doors are opened at destination or during a warm-climate transhipment. Moisture condenses directly onto the cargo surface rather than falling onto it from above.
This matters practically: desiccants address container rain effectively but do little for cargo sweat, because sweat is driven by air entering after the sealed environment is broken. Cargo sweat is managed by controlling how and where a container is opened, not by what was placed inside it.
Mould can establish within 48 hours once condensation begins. On a 28-day voyage, a condensation event in week one produces a fully developed problem long before anyone opens the doors.
🔍 Before loading
The Container Inspection That Prevents Most Claims
Not every container arriving at a factory is fit to load. Containers carry residual moisture from previous cargo, rain exposure at the depot, or inadequate drying after washing. A container that is already damp when it arrives will produce a moisture problem regardless of how well the cargo itself was prepared.
SVC rejects containers at this stage rather than accepting them and hoping. The inspection is short but non-negotiable:
Light test. Close the doors from inside with the interior lights off. Any pinhole of daylight is a hole in the shell — and a hole is a direct water ingress path in rain or heavy seas. This takes thirty seconds and catches a category of problem nothing else will
Smell. A musty or damp odour means residual moisture is already present. For a food cargo, a container carrying chemical, fish or hide odour is rejected outright — cashew kernels absorb ambient odour readily
Water ingress evidence. Rust runs down interior walls, staining along the roof line, or watermarks on the floor indicate prior leakage. A container that has leaked before is likely to leak again
Door gasket integrity. Perished, cracked, or compressed-flat rubber seals allow water and humid air past the door. The gasket should recover its shape when pressed
Floor condition. Splintered, oil-stained, chemically contaminated or visibly damp flooring is a contamination and moisture risk. Wooden container floors are hygroscopic and hold water that later releases into the sealed air
Structural check. Dented panels, bowed walls or a bent door frame can prevent a proper seal even when the gasket itself is sound
The light test is the single highest-value ninety seconds in the entire loading process. It is also the one most frequently skipped when a factory is under schedule pressure during peak season.
📦 Loading
How The Container Is Actually Stuffed
1
Lining Where The Route Requires It
For long tropical-to-temperate routes, a kraft paper or vapour-barrier liner is fitted to the walls and roof before any cargo goes in. The liner does not absorb the condensation — it intercepts droplets before they reach the cartons, and gives them a path to run down the wall rather than fall onto the stack. Liners and desiccants address the same problem from two directions; on high-risk routes both are used together.
2
Floor Dunnage
Cartons are not placed directly on the container floor. Dunnage — pallets or kraft sheeting depending on the buyer's specification — separates the cargo from a wooden floor that may be carrying moisture, and creates a small air gap that prevents wicking from below.
3
Stacking Pattern And The Wall Gap
Cartons are stacked in a documented interlocking pattern for stability, with a deliberate gap maintained between the stack and the container walls. Cartons pressed flat against cold steel are the first to absorb condensation. That gap of a few centimetres is one of the cheapest damage-prevention measures available, and it costs a small amount of loading volume.
4
Desiccant Placement And Quantity
Calcium chloride or clay-based container desiccants are hung along the walls and at the door end, in quantity calculated against voyage length, route climate profile and cargo moisture load — not a fixed number per container. They absorb airborne moisture before it reaches dew point on the shell. Their cost sits at roughly 0.1–0.3% of cargo value, against a moisture loss that can run from 10% to total.
5
Weight Distribution And Securing
Load is distributed evenly fore and aft to stay within axle limits for the inland leg and to avoid stress concentration on the container floor. The final rows at the door end are braced so the stack cannot shift and collapse against the doors in heavy seas — a shifted stack is both a damage event and a serious hazard for whoever opens the container.
6
Photographic Record And Seal
SVC photographs the empty inspected container, the stack at intervals during loading, the completed load, the desiccant placement, and the sealed doors with the seal number legible. If a moisture claim arises at destination, that photographic record is the difference between a resolvable discussion and an unprovable dispute. The seal number is recorded and transmitted to the buyer before departure.
A practical point buyers can act on: specify desiccant quantity, liner requirement and photographic proof explicitly in the purchase order. Requirements written into the contract are enforceable; requirements assumed are not.
⚠️ In transit
What Goes Wrong After The Doors Close
Failure
Mechanism
What prevents it
Container rain
Shell cools below internal dew point; condensation forms on roof and drips onto top cargo layer
Desiccants sized to route; kraft or vapour-barrier liner; loading dry cargo in the first place
Cargo sweat
Cool cargo exposed to warmer humid air, typically when doors open at destination or transhipment
Controlled opening; allowing temperature equalisation before unloading; avoiding opening in rain
Water ingress
Physical hole, perished door gasket, or damaged panel allows direct water entry
Light test and gasket inspection before loading — the only reliable defence
Heat-driven rancidity
Prolonged high temperature accelerates oxidation of the kernel's 45–48% oil content
Minimising quay standing time; avoiding stacking in top-tier fully exposed positions where routing allows
Moisture control plus correct board grade for stack height and voyage length
Odour absorption
Kernels take up ambient odour from container residue or adjacent contamination
Container smell check and rejection; sealed vacuum packaging
Delay compounding
Port congestion extends exposure; desiccant capacity is finite and can be exhausted
Sizing desiccant for realistic transit including congestion allowance, not nominal transit
The last row deserves particular attention during peak season. Desiccants are specified for a duration. A container designed for a 28-day voyage that then spends three weeks in a congested port queue has a moisture protection system operating past its design life. In September, October and November, that is not a hypothetical.
📋 For buyers
What To Specify, And What To Do On Arrival
Write into the purchase order
Desiccant type and minimum quantity per container, specified against your actual route and season
Liner requirement for tropical-to-temperate routes, stated explicitly rather than left to supplier discretion
Photographic documentation of empty container inspection, loading progression, desiccant placement and final seal
Maximum kernel moisture at loading, stated as a contractual figure with CoA evidence
Container seal number transmitted before vessel departure
On arrival
Photograph the seal before breaking it. Confirm the number matches what the supplier transmitted. A mismatched or broken seal changes the nature of any subsequent claim entirely
Photograph the interior before unloading. Condition of the top cartons, any staining on walls or roof, desiccant condition. Once cartons are moved, the evidence of what happened in transit is gone
Do not open in rain, and allow equalisation. Opening a cool container into warm humid air produces cargo sweat on your own premises — damage that occurs after delivery but looks identical to transit damage
Check moisture on arrival, not just on the CoA. The CoA records moisture at loading. Testing at arrival tells you whether the kernel absorbed moisture in transit, which is the actual question
💬 CEO Perspective
💬 CEO Perspective
Container loading is the last point where anyone from our side touches the product. Everything after that is out of our hands for four weeks. That is exactly why we treat those final ninety minutes as a quality stage rather than a logistics task — and why we photograph all of it. A shipment that arrives with a problem and no record is a dispute; one with a full record is a conversation.
— 𝐂𝐄𝐎, 𝐒𝐕𝐂 𝐈𝐧𝐭𝐞𝐫𝐧𝐚𝐭𝐢𝐨𝐧𝐚𝐥 𝐉𝐒𝐂
📦
Want SVC's Container Loading Protocol?
We can share our full pre-loading inspection checklist and photographic documentation standard with prospective buyers, along with route-specific desiccant recommendations for your destination.
