The influence of humidity on corrosion. Air in confined spaces such as warehouses, ship holds, packaging, contains a certain amount of moisture, whose quantity can be determined. Any changes in temperature in the direction of lowering it cause an increase in relative humidity or its condensation, if the dew point is exceeded. Both are unfavorable, as it causes either condensation of moisture in the capillaries of the metal or the formation of water droplets on the surface of the metal. The phenomenon of local increase in humidity in some places of the product preserved for transport may occur when the product is packed in wet crates., contact with moist paper, cardboard, filcem, beaverboard, felt, jute or cotton sack. When heated, these materials exude the moisture they contain, which settles on deeper cold metal parts. The presence of silica gel bags fully saturated with moisture in the package; especially then, when the pouches are in close proximity to metal parts, can also cause (moisture exudation when the temperature in the package is increased. The end result is moisture depositing on the cooler metal, which is the direct cause of its corrosion.