Some cargo forgives a humid container. Steel coil, green coffee, leather and rattan furniture do not.
Moisture damage rarely announces itself at the loading dock. It surfaces weeks later as rust bloom on machined parts, mould across carton liners, or a rejected consignment.
The five suppliers below all build around calcium chloride, yet publish very different performance figures and solve different cargo problems.
What Actually Makes Cargo High Risk
The International Maritime Organization’s CTU Code sets thresholds worth knowing before comparing products. Relative humidity of 40 percent or above is flagged as a corrosion risk for ferrous metal cargo, while 75 percent is where mould becomes a genuine threat to wood, food and textiles.
That gap explains why two containers on the same voyage need different treatment. Canned goods and unfinished rattan do not share a risk profile.
Desiccare’s guidance splits freight into dry goods such as metals and electronics, semi-hygroscopic goods such as textiles and furniture, and hygroscopic goods including grain, coffee, wood and leather. Tropical lanes are treated separately from short trans-Atlantic runs.
1. SUPER DRY
SUPER DRY manufactures calcium chloride and starch container desiccants, reporting protection for up to 90 days and absorption of up to 300 percent of the product’s own weight.
What sets the range apart is how specifically it maps to cargo type rather than container size alone. The company documents solutions across 12 industries and states its products are used by over 40,000 customers.
Its guidance treats leather as one of the most moisture-sensitive materials in global trade, where humidity swings cause mould, staining and odour severe enough to make a shipment unsellable. Footwear is flagged separately because water-based adhesives create mould risk even in synthetic styles.
For agricultural freight, it describes the failure chain exporters recognise: natural moisture evaporates, condenses on the ceiling, then drips back as container rain, producing mould, odour, taste changes and sprouting.
The line splits three ways. DS covers general-purpose shipments hung from walls or lashing rings, DP adds a reinforced outer shell for heavy cargo and long routes, and the SQ, TP and DB formats handle narrow gaps and garment shipments, with DB laid flat across the top of cargo.
Sizing guidance is published openly rather than gated behind a sales call, at four to six bags for a 20ft container and six to twelve for a 40ft. The Knowledge Center also documents how each desiccant category behaves, covering calcium chloride, magnesium chloride, silica gel, clay and molecular sieves with capacity and duration figures for each.
2. Clariant Container Dri II
Container Dri II is a calcium chloride and gelling agent formulation Clariant states can absorb up to 300 percent or more of its own weight, trapping moisture as a thick gel inside a leak-tight pouch.
Its strongest credential sits in food and soft commodity freight. Clariant states it meets Federation of Cocoa Commerce recommendations calling for calcium chloride loading of 65 percent or higher, guidance introduced after silica gel fell out of favour for cocoa shipments.
The formulation is described as non-toxic, safe for food contact, free of Dimethyl Fumarate, and free of Substances of Very High Concern under EU REACH. For exporters shipping into regulated food chains, that documentation trail carries weight. Configurations run to bags, strips, poles and blankets.
3. Absortech
Absortech runs two technologies. Absorpole is liquid-based, using calcium chloride of 77 percent purity that dissolves into brine held in a sealed collector, while AbsorGel uses 94 to 97 percent calcium chloride with modified starch to bind moisture as gel.
That split gives unusual installation flexibility. AbsorGel Hanging holds roughly 3.0 litres, Compact around 2.2 litres for tightly packed cargo, and Blanket around 6.0 litres for palletised freight.
It also publishes a figure most suppliers avoid, stating that 4 to 6 kg of AbsorGel Blanket protects a 30ft container for up to 30 days. Its AbsorTest service measures a cargo’s moisture risk before recommending quantity, which suits shippers who have been guessing at dosage.
4. Desiccare Cargo
Cargo Dry Plus arrives as a three-bag Tyvek strip holding 1,000 g of calcium chloride with a hanging hook, rated by Desiccare at up to 158 percent of its own weight and 50 or more days of protection.
That figure sits below several competitors, and the company presents it plainly. The product is stated as USFDA compliant, which matters for food, pharmaceutical and medical device shippers.
Its public calculator is the practical draw, taking container size, cargo hygroscopicity, route risk and fill level, then returning a unit count. Partial loads are treated differently because free air volume changes the moisture load.
5. WiseSorbent WiseCargo
WiseCargo is a calcium chloride container desiccant sold in five sizes, using PE coated film and composite non-woven double-layer construction to stop absorbed liquid escaping back into the container.
WiseSorbent states absorption above 350 percent at 38°C and 90 percent relative humidity. Its own storefront quotes a lower range for the same line, so confirm the specification against the exact product code before ordering.
Why Absorption Percentages Are Not Directly Comparable
An absorption percentage means little without the test conditions attached to it.
Absortech notes capacity is commonly validated at 90 percent relative humidity and 30°C over 30 days, and states that higher humidity, temperature and duration all push the resulting number up. A 300 percent figure measured over 45 days at 95 percent humidity is not the same claim as 300 percent over 30 days at 90 percent.
So a supplier quoting 350 percent is not automatically beating one quoting 158 percent. Ask for test temperature, humidity and duration, then compare like for like. This same instinct, tracing a claim back to the specific conditions and records behind it rather than taking the headline figure at face value, is becoming standard practice well beyond desiccant sourcing.
A recent look at product traceability in manufacturing covers the same underlying principle: connected records, not a single surface-level number, are what actually let a buyer verify a claim. Teams planning international market expansion usually find unverified assumptions cost more than the research would have.
Conclusion
Matching the supplier to the cargo beats chasing the highest headline number.
Food and cocoa shippers should weight regulatory documentation heavily. Metal and machinery exporters need duration across the full voyage, since corrosion risk begins at far lower humidity than mould. Garment and furniture shippers should look hardest at format, because a bag that does not fit the load protects nothing.
FAQ
- How many desiccant bags does a 40ft container need?
SUPER DRY suggests six to twelve bags for a 40ft container and four to six for a 20ft, though the figure shifts with cargo type, shipment duration and climate.
- Is calcium chloride better than silica gel for ocean freight?
For long sea voyages, capacity and duration favour calcium chloride heavily. Silica gel saturates quickly and works well only in a narrow temperature band, while calcium chloride products are rated in the hundreds of percent and hold moisture for weeks.
- What is container rain?
Condensation forms on container walls and ceilings when temperatures swing in transit, then drips onto the cargo below. Warm humid air trapped at loading cools overnight, reaches dew point, and releases the moisture it carried.
- Can container desiccants be reused?
Calcium chloride desiccants cannot be reused once saturated, because absorption is a chemical change rather than a surface effect. Fresh units are needed for each shipment.