The two most common hammock materials are cotton and polyester. Cotton is natural and can be softer on the skin, but will weather faster and will mold if not dried after it becomes wet. Polyester is a synthetic material so may not be as cozy to the touch. However, it is more weather resistant and will not mold. So the answer depends on your intended use. If comfort is the priority and you will take care of your hammock, go for cotton. If you need durability even with some neglect (leaving the hammock out in the rain), then go for polyester.
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