The two most common dunnage bag materials are multi-ply kraft paper and woven polypropylene (PP), and each fits a different set of shipping conditions.
Kraft paper bags are cost-effective and perform well for single-use, dry-environment shipments — general dry goods, packaged food-grade products, and palletized cartons moving by rail or road over shorter distances.
Woven PP bags are more resistant to moisture, punctures, and rough handling, making them the better fit for ocean freight, longer transit times, and cargo with sharper edges or higher pressure requirements.
Neither option is universally 'better' — the right choice comes down to the cargo type, transit duration, handling conditions, and whether the bag needs to survive multiple legs of a multimodal journey. A quick way to decide: if the shipment spends meaningful time exposed to sea air or humidity, woven PP is usually the safer default.