Placement matters as much as quantity
The right amount of desiccant in the wrong place still loses cargo. Silica gel protects the air around it; water vapor has to reach the gel by diffusion, and diffusion is slow in still, packed air. So placement is about giving the desiccant access to the whole package volume and putting it where moisture and condensation actually concentrate. The two failure modes are burying the gel where air can't circulate to it, and clustering all of it in one corner so the far side of the package stays humid. Good placement spreads the desiccant through the volume and positions it near the cold or moisture-prone surfaces.
- Right quantity, wrong place = lost cargo.
- Silica gel protects the air around it; vapor reaches it slowly by diffusion.
- Failure modes: gel buried out of airflow, or all clustered in one corner.
- Spread desiccant through the volume; place near cold/moisture-prone surfaces.
Inside the unit pack and carton
Place sachets in the air space, not crushed under dense goods where air can't reach them. For a product in a sealed bag, put the sachet inside the bag with the product. For a carton, distribute multiple smaller sachets rather than one large one in a corner — three 2 g sachets spread across a carton protect better than a single 6 g sachet in one place. Keep sachets away from sharp edges that could puncture them, and avoid direct contact with surfaces that must not be marked. For electronics in a moisture-barrier bag, the sachet goes inside the sealed bag; the bag is the barrier and the sachet manages the trapped air.
- Put sachets in the air space, not crushed under dense goods.
- Sealed-bag goods: sachet inside the bag with the product.
- Distribute several small sachets over one large corner sachet.
- Keep away from puncturing edges and surfaces that must stay unmarked.
- MBB electronics: sachet inside the sealed bag to manage trapped air.
Master cartons, pallets, and stacking
At master-carton and pallet level, moisture concentrates at the top (warm humid air rises and condenses on the cold container roof, dripping down) and at the outer faces exposed to the container air. Place supplementary desiccant high in the load and around the perimeter, not just at the base. For palletized loads, a desiccant bag at the top of the stack under the cap sheet catches descending condensation. Wrap or cap pallets so the desiccant is working inside a defined volume rather than the open container. Remember the nested-environment rule: unit packs need their own desiccant; the pallet-level dose is supplementary, not a substitute.
- Moisture concentrates at the top (roof condensation) and outer faces.
- Place supplementary desiccant high in the load and around the perimeter.
- Palletized loads: a bag at the top under the cap sheet catches dripping condensation.
- Cap/wrap pallets so desiccant works inside a defined volume.
- Pallet-level dose is supplementary to unit-pack desiccant, not a replacement.
Container strip hanging patterns
Container desiccant strips protect the container airspace and must be hung where condensation forms — high on the walls and near the doors and roof, distributed along the container length, not bunched at one end. The standard pattern hangs strips from the lashing rails down the side walls at regular intervals, with extra near the door end where temperature swings are sharpest. Do not lay strips on the floor or bury them in the cargo: they work by sitting in the moving container air. Hang them so saturated strips (which get heavy and, for high-capacity types, gel-filled) cannot fall onto or leak toward the cargo. Combine container strips with carton-level sachets — strips handle the airspace, sachets handle each carton's micro-climate.
- Hang strips high on walls and near doors/roof where condensation forms.
- Distribute along the container length; don't bunch at one end.
- Standard: from lashing rails down side walls, extra at the door end.
- Never lay strips on the floor or bury them — they need moving air.
- Hang so saturated/heavy strips can't fall onto or leak toward cargo.
- Pair container strips (airspace) with carton sachets (micro-climate).
What to avoid
A short list of placement mistakes that quietly cause claims: sealing desiccant outside the moisture barrier (it then protects the wrong volume); placing all desiccant at the floor of a load where rising warm air and roof condensation never reach it; letting sachets contact food, pharma, or finished surfaces directly when the spec requires separation; reusing positions from a different cargo geometry without rechecking airflow; and forgetting to remove the protective outer pouch from fresh sachets before insertion (or, conversely, leaving sachets exposed to ambient air for hours before sealing, which pre-saturates them). Each is cheap to avoid on the packing line and expensive to discover at destination.
- Don't seal desiccant outside the moisture barrier.
- Don't put all desiccant at the floor — it can't reach roof condensation.
- Respect required separation from food/pharma/finished surfaces.
- Recheck airflow when cargo geometry changes; don't blindly reuse positions.
- Insert fresh sachets promptly; don't let them pre-saturate in ambient air.