The fabric draped across your rain jacket, camping tent, or everyday backpack likely contains nylon, a synthetic wonder that has revolutionized outdoor gear and everyday products since the 1930s. But does nylon truly keep water out, or does it merely resist moisture before eventually giving in?
Nylon is water-resistant, not waterproof, in its untreated, standard form. This distinction matters more than most people realize. Water-resistant materials slow down moisture penetration but cannot completely prevent water from seeping through under pressure or prolonged exposure. Waterproof materials, by contrast, create an impenetrable barrier that blocks water entirely.
Understanding this difference transforms how you choose gear, maintain fabrics, and set realistic expectations for your nylon products.
The Chemistry Behind Nylon’s Relationship With Water
Nylon belongs to the polyamide family—a group of synthetic polymers created through chemical reactions between diamines and dicarboxylic acids. The molecular structure determines how nylon interacts with water at a microscopic level.
Why Nylon Resists Water (But Not Completely)
The polyamide chains in nylon contain hydrophobic regions that naturally repel water molecules. These non-polar sections create surface tension that causes water droplets to bead up rather than immediately absorb into the fabric. Think of it like oil meeting water—they don’t mix readily.
However, nylon also contains hydrophilic amide groups scattered throughout its molecular structure. These polar segments actually attract water molecules, creating weak hydrogen bonds. Over time, or under pressure, water finds these vulnerable spots and penetrates the fabric.
| Property | Untreated Nylon | Coated Nylon | Other Fabrics (Cotton) |
|---|---|---|---|
| Initial water contact | Beads up | Completely repels | Absorbs immediately |
| Under pressure | Penetrates slowly | Blocks effectively | Saturates quickly |
| Moisture absorption | 3-9% by weight | <1% | 25-27% |
| Drying time | Fast (1-4 hours) | Very fast (30 min-2 hours) | Slow (8-24 hours) |
The Weave Factor
Water resistance in nylon depends heavily on fabric construction. Tightly woven nylon with high thread counts creates smaller gaps between fibers, making it harder for water molecules to slip through. Loosely woven nylon, conversely, offers minimal resistance.
Ripstop nylon—reinforced with thicker threads in a crosshatch pattern—provides excellent tear resistance but slightly reduced water resistance due to its grid structure. Taffeta nylon, with its tight plain weave, offers superior moisture protection while maintaining flexibility.
Water-Resistant vs. Waterproof: The Critical Distinction
These terms are not interchangeable, despite marketing materials that blur the lines.
Water-Resistant Defined
Water-resistant fabrics repel water to varying degrees but eventually allow moisture penetration. They’re rated using millimeters of water column pressure—a measurement that indicates how much water pressure the fabric can withstand before leaking.
- 500-1,500mm: Light water resistance (brief drizzle)
- 1,500-5,000mm: Moderate water resistance (steady rain for 30-60 minutes)
- 5,000-10,000mm: High water resistance (heavy rain for several hours)
Standard untreated nylon typically falls into the 500-2,000mm range.
Waterproof Defined
Waterproof fabrics prevent water penetration regardless of pressure or duration. Technical waterproofing starts at 10,000mm and extends beyond 20,000mm for professional-grade gear.
True waterproofing requires additional treatments—coatings, laminates, or membranes applied to nylon’s surface or embedded within the fabric structure.
How Manufacturers Transform Nylon Into Waterproof Material
The outdoor industry has developed sophisticated methods to enhance nylon’s natural water resistance into genuine waterproofing.
Polyurethane (PU) Coating
PU coating involves applying a thin layer of polyurethane to nylon’s surface. This treatment creates a flexible, waterproof barrier that bonds with the fabric while maintaining breathability to some degree.
Benefits include affordability, durability, and effectiveness. Drawbacks involve potential delamination over time and reduced breathability compared to membrane technologies.
Durable Water Repellent (DWR) Treatment
DWR treatment coats individual nylon fibers with fluoropolymer chemicals that dramatically increase hydrophobic properties. Water forms tight beads that roll off the surface rather than spreading or absorbing.
This treatment is not permanent. Friction, washing, and UV exposure gradually wear away DWR coatings, requiring reapplication every 20-40 uses depending on conditions.
Laminated Membranes
Membrane technology represents the pinnacle of waterproofing. Manufacturers bond ultra-thin layers of materials like PTFE (polytetrafluoroethylene) or polyester membranes to nylon fabric. These membranes contain billions of microscopic pores—too small for water droplets but large enough for water vapor molecules.
The result? Complete waterproofing with maintained breathability, allowing sweat to escape while blocking external moisture.
Silicone Coating
Silicone-coated nylon (often called silnylon) combines exceptional waterproofing with remarkable lightness. The silicone impregnates the fabric rather than sitting as a surface layer, creating a slippery, water-shedding surface.
Backpackers and ultralight enthusiasts favor silnylon for tents and tarps, though the slippery surface makes seam sealing challenging.
Types of Nylon and Their Water Performance
Not all nylon is created equal. Different formulations and constructions offer varying levels of moisture protection.
Nylon 6 vs. Nylon 6,6
Nylon 6 absorbs water more readily than Nylon 6,6 due to differences in molecular structure. Nylon 6 can absorb up to 9% of its weight in water, while Nylon 6,6 typically absorbs around 3-4%.
This distinction matters in applications where dimensional stability is crucial. Wet nylon 6 can stretch and distort more than its cousin.
Denier Ratings and Water Resistance
Denier measures fiber thickness—the weight in grams of 9,000 meters of yarn. Higher denier numbers indicate thicker, heavier fibers.
- 20-70D: Ultralight, less durable, moderate water resistance
- 210-420D: Standard weight, balanced properties
- 500-1000D: Heavy-duty, excellent durability, superior water resistance when coated
Thicker fibers create tighter weaves when properly constructed, enhancing natural water resistance before any treatments are applied.
Ballistic Nylon
Ballistic nylon (typically 1050D or higher) was originally developed for military body armor. Its extremely tight weave and thick fibers provide excellent abrasion resistance and inherent water resistance, though it still requires coating for genuine waterproofing.
Real-World Applications: Where Nylon’s Water Properties Matter
Understanding nylon’s water behavior becomes crucial when selecting products for specific uses.
Outdoor Gear
Backpacks utilize coated nylon (typically 210-500D) on bottom panels and weather-exposed areas. The 30-70D nylon on shoulder straps requires less waterproofing since it contacts your body. Quality packs combine different nylon weights strategically.
Tents demand serious waterproofing. Floor fabrics typically use 70-150D nylon with 3,000-10,000mm coating, while rainflies use 20-70D nylon with 1,500-5,000mm coating. Lighter weights reduce pack weight; heavier coatings increase weather protection.
Rain jackets layer multiple technologies—DWR on the outer shell, waterproof membranes in the middle, and mesh or light nylon linings inside. This three-layer construction (or two-layer with hanging liners) balances waterproofing, breathability, and durability.
Everyday Items
Luggage uses coated 420-1000D nylon on high-wear areas. The coating provides water resistance sufficient for brief rain exposure during travel transitions, though extended downpours will eventually penetrate.
Phone cases and wallets feature 200-420D coated nylon that keeps devices dry during normal use but shouldn’t be trusted for underwater or extreme wet conditions.
Umbrellas rely on 190-210T (thread count) nylon fabric with PU coating on the underside. The tight weave combined with coating creates reliable rain protection.
Testing Nylon’s Water Resistance at Home
You can evaluate your nylon gear’s current water resistance through simple tests.
The Water Drop Test
Place a few drops of water on your nylon fabric. High-quality DWR treatment causes water to bead up into tight spheres that roll off easily. Water that spreads into patches or slowly soaks in indicates worn treatment needing reapplication.
The Spray Test
Use a spray bottle to mist water across the fabric’s surface. Well-treated nylon should shed water immediately. Darkening fabric or wet spots signal compromised waterproofing.
The Pressure Test
Press your thumb against a water droplet sitting on the fabric. If water pushes through to your thumb, the waterproofing has degraded. This mimics pressure from backpack straps, shoulders, or sitting.
Maintaining Water Resistance in Nylon Products
Proper care extends the life of waterproof treatments significantly.
Washing Guidelines
Machine wash nylon items on gentle cycles with technical fabric cleaners—never regular detergent. Standard detergents leave residues that interfere with DWR coatings.
Temperature matters: warm water (30-40°C or 85-105°F) cleans effectively without damaging coatings. Hot water can deteriorate PU coatings and DWR treatments.
Reactivating DWR
Heat can temporarily reactivate worn DWR treatments. After washing, tumble dry on low heat for 20-30 minutes or iron on low setting (with a cloth barrier). The heat causes the fluoropolymer chains to stand upright again, restoring water repellency.
Reapplying DWR
When heat reactivation no longer works, apply spray-on or wash-in DWR products. Spray versions target specific areas but require even application. Wash-in products coat the entire garment uniformly but use more product.
Clean the fabric thoroughly before reapplication. DWR cannot bond properly to dirty or oily surfaces.
Storage Practices
Store nylon gear loosely folded or hung in cool, dry locations. Avoid compression for extended periods—creases can damage waterproof coatings. Keep items away from direct sunlight, which degrades both nylon fibers and waterproof treatments through UV exposure.
When Nylon Fails: Understanding Limitations
Even the best waterproof nylon has boundaries.
Seam Vulnerability
Seams remain the weakest link in waterproof nylon products. Needle holes create pathways for water penetration. Quality manufacturers apply seam tape—thin polyurethane strips heat-bonded over stitching—to seal these vulnerabilities.
Check seam tape regularly. Peeling or cracked tape requires replacement to maintain waterproofing.
Abrasion Damage
Physical wear gradually removes waterproof coatings. High-friction areas—backpack bottom panels, jacket cuffs, and tent floors—lose protection faster than other sections.
Inspect wear points annually and apply patch kits or localized DWR treatment to restore protection.
Temperature Extremes
Freezing conditions cause water in nylon’s molecular structure to expand, potentially damaging waterproof coatings. Extreme heat (above 60°C or 140°F) can cause PU coatings to delaminate or melt.
Chemical Exposure
Bug spray, sunscreen, and body oils degrade DWR treatments rapidly. Clean nylon products after exposure to these substances. Saltwater requires immediate rinsing—salt crystals attract moisture and can corrode coatings over time.
Alternative Materials: How Nylon Compares
Context helps us appreciate nylon’s strengths and weaknesses.
| Material | Water Resistance | Weight | Durability | Breathability | Cost |
|---|---|---|---|---|---|
| Untreated Nylon | Moderate | Light | High | Good | Low |
| Coated Nylon | High to Waterproof | Light-Medium | High | Fair | Medium |
| Polyester | Similar to nylon | Similar | Very High | Good | Low-Medium |
| Gore-Tex (PTFE) | Completely Waterproof | Medium | High | Excellent | High |
| Waxed Canvas | Water-resistant | Heavy | Excellent | Poor | Medium-High |
| Silicone-coated Nylon | Waterproof | Very Light | Medium | Poor | Medium |
Polyester offers comparable water resistance with better UV stability and lower moisture absorption (0.4% vs. nylon’s 3-9%). However, nylon provides superior abrasion resistance and flexibility.
Gore-Tex and similar membranes deliver unmatched waterproof breathability but at premium prices. Budget-conscious consumers find coated nylon offers excellent value.
Waxed canvas appeals to traditionalists seeking natural aesthetics and repairability, though weight and reduced breathability limit modern applications.
Innovations in Water-Resistant Nylon Technology
The fabric industry continues advancing nylon’s water-handling capabilities.
Fluorine-Free DWR
Environmental concerns about perfluorinated compounds (PFCs) have driven development of fluorine-free DWR treatments. These newer formulations use hydrocarbon-based polymers instead of fluoropolymers.
Performance matches traditional DWR in many applications, though durability remains slightly lower. Expect to reapply fluorine-free treatments more frequently.
Electrospun Nanofiber Membranes
Cutting-edge research applies electrospinning technology to create ultra-thin nylon membranes with controlled pore sizes. These membranes achieve waterproofing and breathability through physical structure rather than chemical coatings, potentially offering superior durability.
Smart Textiles
Phase-change materials and moisture-responsive fibers represent the frontier. Some experimental nylon fabrics adjust their water resistance dynamically based on humidity levels, though commercial availability remains limited.
Key Takeaways
- Untreated nylon is water-resistant, not waterproof—it slows water penetration but cannot completely block moisture indefinitely.
- Coatings and membranes transform nylon from water-resistant to fully waterproof, with ratings from 1,500mm for light rain protection to 20,000mm+ for extreme conditions.
- DWR treatment requires regular maintenance—reactivate with heat after washing and reapply when water no longer beads on the surface.
- Seams compromise even the best waterproof nylon—check seam tape integrity regularly and repair damage promptly to maintain protection.
- Different applications demand different solutions—ultralight backpacking prioritizes coated silnylon, while mountaineering requires heavy-duty coated nylon with superior abrasion resistance.
Frequently Asked Questions (FAQ)
Can nylon fabric be made completely waterproof?
Yes, nylon becomes completely waterproof through coatings like polyurethane, silicone treatments, or laminated membranes such as Gore-Tex. Standard untreated nylon is only water-resistant. Waterproof nylon typically has ratings of 10,000mm or higher on the water column pressure scale, meaning it can withstand substantial water pressure without leaking.
How long does waterproof coating last on nylon?
Waterproof coatings typically last 2-5 years with proper care and moderate use. PU coatings may delaminate after 3-7 years depending on storage conditions and exposure. DWR treatments need reapplication every 20-40 uses or annually for regularly used items. UV exposure, abrasion, and improper washing accelerate coating degradation, while careful maintenance extends longevity.
Does water damage nylon fabric permanently?
Water itself does not permanently damage nylon, but prolonged moisture exposure can degrade coatings and promote mildew growth. Nylon absorbs 3-9% of its weight in water, causing temporary swelling and potential stretching. The fabric returns to normal dimensions when dried properly. However, freezing while wet or exposure to saltwater without proper rinsing can damage both fibers and waterproof treatments.
What’s better for rain protection: coated nylon or membrane nylon?
Membrane nylon (like Gore-Tex) offers superior breathability while maintaining complete waterproofing, making it ideal for high-activity use where sweat management matters. Coated nylon provides excellent waterproofing at lower cost but reduced breathability, making it better for stationary use or budget-conscious consumers. For extreme rain in active pursuits, membrane technology wins; for general rain protection, quality coated nylon suffices.
Can you make nylon waterproof at home?
Yes, you can enhance nylon’s water resistance at home using spray-on or wash-in DWR products available at outdoor retailers. For stronger waterproofing, apply silicone-based sealants or specialized waterproofing sprays designed for fabrics. However, home treatments cannot match factory-applied PU coatings or laminated membranes. These DIY solutions work best for restoring worn treatments or improving moderately water-resistant items.
Why does my nylon jacket stop repelling water?
DWR coating degradation is the primary culprit. Friction from backpack straps, body oils, dirt buildup, and washing with regular detergent all break down the hydrophobic layer. Additionally, improper washing or drying can damage treatments. Try cleaning the jacket with technical fabric cleaner, then tumble drying on low heat to reactivate the DWR. If water still doesn’t bead up, reapply DWR treatment.
Is nylon better than polyester for waterproof jackets?
Both work well, but nylon offers superior abrasion resistance and flexibility, making it preferred for technical outdoor gear. Nylon feels softer against skin and packs smaller. However, polyester absorbs less moisture (0.4% vs. nylon’s 3-9%) and resists UV degradation better, making it ideal for marine applications and prolonged sun exposure. For rain jackets with frequent use, coated nylon typically provides better long-term performance.
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