Nylon is a synthetic polymer, a type of plastic called a polyamide, widely used in textiles for its strength and durability. Regarding moisture, nylon is inherently water-resistant, but not naturally waterproof. The protection level depends entirely on the fabric’s physical construction and the chemical treatments applied during manufacturing. Achieving true waterproofing requires modifying the material beyond its basic chemical structure.
Nylon’s Chemical Interaction with Water
Hydrophobic Structure
The polymer chains in nylon contain long segments of carbon and hydrogen atoms, which are generally hydrophobic. This structure gives nylon initial resistance to surface wetting, causing water droplets to sit on top of the fabric.
Hydrophilic Bonds
However, the nylon chain also contains repeated, slightly polar amide bonds. These amide groups are hydrophilic, meaning they attract water molecules and can form hydrogen bonds. This dual nature means that while nylon resists surface water, the bulk material can absorb moisture over time. For instance, Nylon 6 can absorb up to 3.5% of its weight in water when exposed to humidity. This absorption causes fibers to swell, which can slightly reduce the fabric’s strength and affect its dimensions.
How Weave Affects Water Performance
Moving from chemical properties to physical construction, the way nylon fibers are woven together is a primary factor in water performance. A tightly constructed weave creates a mechanical barrier, often more effective at repelling light water exposure than the polymer’s inherent chemistry. Water droplets have high surface tension, making it difficult for them to pass through the tiny gaps between threads. Fabrics with a high thread count and specialized patterns, such as ripstop or twill weaves, maximize this physical resistance, forcing water to bead up and roll off the surface. Conversely, nylon used in a loose knit has larger pores, allowing water to pass through easily.
Enhancing Nylon with Surface Treatments
Durable Water Repellent (DWR)
To move beyond basic water resistance and achieve true water repellency, manufacturers rely on specialized chemical applications. The most common enhancement is a Durable Water Repellent (DWR) coating, applied to the fabric’s exterior surface. DWR is a thin layer of highly hydrophobic chemicals that drastically reduces the fabric’s surface energy. The DWR application causes water to form near-spherical beads, making them roll off easily. This treatment prevents the outer layer from becoming saturated, which would otherwise compromise breathability.
Waterproof Coatings
For full waterproofing, a coating of polyurethane (PU) or polyvinyl chloride (PVC) is applied to the fabric’s interior side. These coatings create a continuous, impermeable film that physically blocks water from passing through the material. This makes the fabric waterproof, though sometimes reducing breathability.
Real-World Use and Water Resistance
Water-Resistant Applications
The distinction between water-resistant and waterproof nylon is important for consumers selecting outdoor gear. Water-resistant nylon, relying on a tight weave and perhaps a light DWR coating, is excellent for items like backpacks or windbreakers exposed to short periods of light rain. These materials are lightweight and quick-drying, as absorbed moisture readily evaporates.
Waterproof Applications
Waterproof nylon, which incorporates a PU coating or laminated membrane, is necessary for items like rain jackets and tents where complete protection from heavy or constant moisture is required. The physical barrier prevents water penetration, making the item impervious to the elements. However, this protection can sometimes reduce the fabric’s ability to allow water vapor, like sweat, to escape, affecting comfort during high-exertion activities.