When such hygroscopic raw materials as rubber and plastic are used, process difficulties can occur in a humid atmosphere. Moulded products made of these materials can develop “air” pockets caused by stress; other imperfections can result from moisture adsorbed by the raw materials. In automobile production, it may be virtual impossibility to vulcanize tyre cord to rubber when the cord contains moisture. Dry Air used for storage and possibly in the production area can alleviate this situation.