Nylon is naturally water resistant and is often coated to make it waterproof. Nylon fibers do not rot, so storing a wet nylon tent will not damage it. However, nylon tents should be thoroughly dried before storing because mildew can still form on the surface. Cotton fibers are very absorbent and susceptible to rot. Water absorbed by the canvas can make it very heavy. Canvas may be coated to improve its water resistance.
Nylon fabric is a light and airy material originally designed to replace natural silk. Canvas is woven from thick fibers to give it strength and durability, making canvas much heavier than nylon. In wet conditions, canvas absorbs water, making it even heavier. The pole structure used for canvas tents is heavier and more bulky than the lightweight poles used in nylon tents.
Canvas and nylon are both strong, durable fabrics. Canvas is more durable than nylon. Canvas can be easily be mended with a sewing kit, while nylon requires a special repair patch. The heavy thread in canvas resists letting rips grow larger. While regular nylon fabric rips easily, rips top nylon uses a special weave to stop rips from growing. Canvas may rot if not cared for properly.
Cotton breathes much better than nylon, keeping the interior humidity level with the outside. Nylon tents may allow condensation to form on the walls and depend on mesh panels to provide ventilation. Canvas does not transfer heat as quickly as nylon, keeping the tent interior cooler in warm weather and warmer when it is cool outside. A nylon tent can become unbearably hot very quickly in direct sunlight.