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Date：2026-10-15Plastic storage cabinet mould is best tackled in two stages. The boards take iHeir-ECO plastic antimicrobial agent in the mixing stage at 0.3%-1.0% (PE and PP 0.3%-0.5%, PVC 0.5%-1.0%, on total plastic weight), and the packing takes iHeir-D gas-phase antimicrobial and mould inhibitor at 0.1-0.2 g of active per sheet. This article explains why the boards and the packing are treated apart, how each is dosed, and how the cabinet should be ventilated and dried before dispatch.
1. Why a plastic storage cabinet moulds more easily than open shelving
A storage cabinet is, after all, a closed box. Shut the door and the air inside barely moves; it warms up through the day, cools at night, and moisture condenses on the inner faces. Open shelving and pallets do not behave this way, but a sealed cabinet does. That is why, in the same warehouse, the inside of a cabinet spots first while the outside still looks clean.
The body is assembled from several boards, and between the side panels, the back, the shelves and the clips there are many joints. They are narrow, but they are exactly where dust and water collect: a cloth cannot reach in while damp air can, so mould takes hold in the seams. Add to that the dense stacking and the bulk of the cabinet, and the air inside a stack barely moves, so once damp takes hold it affects the whole stack.
The boards carry a hidden source of moisture as well. Plastic granules are dried before processing, and when drying is incomplete or the proportion of regrind is high, water is left inside the extruded or moulded board. If the boards are assembled and boxed straight away, the moisture is sealed inside a closed structure and only comes out when the goods reach a hot, humid region, which shows as a musty smell on opening and spots that come back after being wiped off.
2. The boards and the packing at a glance
The table lines up the two stages with the place where the agent goes in or in, the figure and the points to watch, as a first draft of a process and packing instruction.
| Stage | Where | How | Figure or criterion | Points to watch |
|---|---|---|---|---|
| Cabinet boards | Mixing drum | Masterbatch blended with the granules before extrusion or moulding | iHeir-ECO at 0.3%-1.0% (PE/PP 0.3%-0.5%, PVC 0.5%-1.0%, on total plastic weight) | Keep processing temperature below 320 degrees; add before plastification and stir evenly |
| Inner packing | Inside the carton, between the boards | Gas-phase paper or sachets placed by layer | iHeir-D at 0.1-0.2 g of active per sheet | Separate the inhibitor from metal clips and runners with paper; seal the carton before it goes to store |
| Ventilation before dispatch | Assembly area and finished-goods store | Door-open ventilation and humidity control | Relative humidity below 60% | Leave the doors ajar to ventilate, stack off the wall and off the floor, ship first-in first-out |
Three rows make the division of work clear: the first is done in the board, the second in the packing, and the third is the assembly and warehouse discipline that holds the result. Miss any row and the problem shows when the customer opens the carton or puts the cabinet on the shelf.
3. The cabinet boards: ECO on total board weight
The boards take iHeir-ECO plastic antimicrobial agent at 0.3%-1.0%, with PE and PP at 0.3%-0.5% and PVC at 0.5%-1.0%, always on total plastic weight. It is a grey-white powder, supplied as an internal masterbatch, blended with the granules in the mixing stage; it suits both extruded board and moulded parts and runs on existing plant without extra equipment.
Its advantage is that the active ingredient runs through the whole board rather than sitting on the surface, so a panel keeps its protection after washing and after being wetted and dried repeatedly. Add it before plastification; mix it badly and one batch of board comes out good on one side and poor on the other. Watch the processing temperature above all: thermal stability reaches 240 degrees, and the melt should be kept below 320 degrees, because an excessive temperature drives the active off and the addition is wasted.
4. Inner packing: D gas-phase paper in the carton
The inner packing takes iHeir-D gas-phase antimicrobial and mould inhibitor, supplied as paper or sachets, each holding 0.1-0.2 g of active. It is a placement product: the active is released slowly and spreads evenly through a closed space, which suits whole cartons of finished goods and long sea voyages, and it can go between the boards, in the bottom of the carton and near the opening.
Placement comes down to separation and closure. The inhibitor must be separated from the goods by paper, because a cabinet with metal clips, runners or dark dye carries a risk if the two touch, and the usual method is to lay the paper in the bottom of the carton and tuck sachets between the boards before sealing. That spreads the vapour far more evenly than dropping sachets into a corner. In a large, humid warehouse the quantity has to be raised to suit the volume and the humidity rather than copied from a small carton.
Keep this stage separate from the board stage. The ECO goes into the board and looks after the cabinet itself; the D goes into the packing and looks after transport and storage. Do both and the goods carry an unbroken line of protection from assembly to the customer.
5. Ventilation and drying before dispatch, and storage
Between assembly and loading there is one operation that can waste the earlier work. Hold relative humidity in the assembly area and the finished-goods store below 60%, leave the cabinet doors ajar so the air inside exchanges with the shop, and only then box the goods; in the rainy season run a dehumidifier or ventilate on a schedule rather than let damp ruin a whole stack in a few days.
Stacking and dispatch follow the same discipline. Keep finished goods off the wall and off the floor, leave an air gap between stacks and turn stock first-in first-out. Export lots are sealed and loaded into the container, where the day-night temperature swing makes condensation run down the inside of the walls, and humidity control at that point matters as much as it does in the warehouse. The way the stages are separated follows the note on moisture and mould in shipping containers, and it runs alongside the board addition rather than replacing it.
6. Questions that come up: packing only, and reworking a cabinet that has already moulded
Is gas-phase inhibitor in the packing enough, with no treatment in the boards? Not advisable. The vapour in the packing looks after transport and storage only, and once the cabinet is unpacked and assembled and the paper is thrown away, the boards have no second line of defence. A closed cabinet that keeps taking on moisture cannot be held by that small quantity of vapour, so the board itself has to be treated.
Can a cabinet that has already gone damp and spotted be reworked? It depends where the mould is. Where it sits only in the film of dust on the surface, clean the parts, dry them thoroughly, box them again and add gas-phase inhibitor to the packing. Where it has reached the assembly joints or the board itself, cleaning only addresses the surface and the growth returns, so those lots are better isolated and downgraded. Reworked parts must be dried right through, or boxing them damp seals the water back in.
Two points carry the work. The boards take iHeir-ECO plastic antimicrobial agent at 0.3%-1.0% on total plastic weight in the mixing stage, and the inner packing takes iHeir-D gas-phase antimicrobial and mould inhibitor at 0.1-0.2 g of active per sheet. Ventilating the doors ajar and holding relative humidity below 60% before dispatch then keeps the work done at both stages in the goods. Samples and TDS are available to check the configuration.
