- Hygroscopic goods must have the lowest possible water content when they are packed in the container. Where there is no experience for a particular product, it is advisable to comply with the lower water content limit which is provided for transport in conventional holds. If a water content of 10 - 12% has in the past been recommended, the goods should be packed at 10% and below (see TIS, where the upper and lower temperature limits are stated). However, caution is required in that an excessively low water content may result in impairment of quality, such as drying-out of tobacco, cracking of lumber or loss of aroma in spices. One vital factor is the size of the temperature/dew point difference of the equilibrium moisture content, which should be > 6°C. Water content cannot be reduced for fruit and vegetables. They must be packed at the lowest possible temperature and should always be kept away from solar radiation.
- It must be possible to cool the goods rapidly in the container, with the mass of the cargo in the container and the accessibility of the surfaces to the air playing a major part, in order to improve the transfer of heat from the cargo to the container wall.
- Where the possibility of sweating during the voyage is suspected, the surface of the cargo should be protected from dripping water. Paper and gunny cloth are more suitable than plastic sheet, as using the latter may simply move the condensation surface to the underside of the sheet, resulting in the sweat coming into direct contact with the cargo. Relatively large quantities of sweat may, however, only be kept away from the cargo with nonwoven fabric.
- Using an anticondensation film, one ply of which is highly impermeable to gas and vapor while the other is capable of absorbing up to 150 g of water per m², would also be favorable.
- Containers packed with hygroscopic goods or fruit and vegetables should be transported below deck, as the temperature of the air and thus of the container walls drops substantially more gradually here and heat may be dissipated by vigorous ventilation or, in the event of a major drop in air temperature, ventilation may also be turned down.
- It is necessary to cool the containers as they are always kept and transported in the open at the port of destination, so that containers with a hygroscopic cargo and at a high temperature are at extreme risk. The doors may, if necessary, be opened in the port, so immediately suspending the formation of container sweat.