Is Nylon Waterproof? Understanding the Water Resistance of Nylon

Nylon, a synthetic polymer invented by Wallace Carothers and his team at DuPont in 1935, has become a ubiquitous material in various industries due to its versatility, strength, and durability. While nylon’s applications range from clothing to industrial uses, a common question that arises is whether nylon is waterproof. To answer this, it is essential to understand the inherent properties of nylon and how it interacts with water.

What is Nylon?

Nylon, also known as polyamide (PA) in chemical terms, is a type of thermoplastic resin characterized by a molecular backbone containing repeated amide groups. It is the world’s first synthetic fiber and is commonly referred to as “nylon” or “PA.” Nylon encompasses various types, including aliphatic polyamides (PA), aliphatic-aromatic polyamides (PA), and aromatic polyamides (PA). Among these, aliphatic polyamides are diverse in variety, have large production volumes, and find extensive applications. Therefore, their nomenclature is based on the specific number of carbon atoms in the synthetic monomer.

In textiles, nylon is commonly used to make clothing, luggage, and other consumer goods. Its lightweight nature and high tensile strength also make it ideal for industrial applications. In industrial applications, nylon’s exceptional properties make it indispensable. Nylon’s durability and resistance to heat and chemicals make it ideal for components like gears, bearings, and bushings within engines and transmissions.

History of Nylon Development

The history of nylon development traces back to synthetic polyamide research initiated in 1928. In 1935, American scientist Wallace Carothers and his team conducted theoretical studies on polymerization reactions, leading to the synthesis of high molecular weight linear condensation polymer known as polyhexamethylene adipamide (nylon 66) from adipic acid and hexamethylenediamine. From 1936 to 1937, DuPont in the United States successfully produced nylon 66 fibers using melt spinning, based on Carothers’ research, and branded the fiber product as “nylon.” This marked the industrialization of the first polyamide variety in 1939. Concurrently, in 1938, German chemist Paul Schlack developed and industrialized the production of polyamide 6 (nylon 6) using ε-caprolactam, with full-scale production commencing in 1941.

Over the ensuing half-century, numerous polyamide products have been introduced. Aliphatic polyamides (PA) include PA-6, PA-610, PA-612, PA-1010, PA-11, PA-12, and PA-46. Aromatic polyamides encompass fibers like poly(p-phenylene terephthalamide) (commonly known as Kevlar 1414) and poly(m-phenylene isophthalamide) (known as Nomex 1313) in China. Hybrid polyamides include poly(m-xylylene adipamide) (MXD6) and poly(p-phenylene adipamide) (nylon 6T).

Is Nylon Waterproof?

nylon is inherently water-resistant but not entirely waterproof. Its water resistance can be significantly enhanced through various treatments, coatings, and construction techniques.

Effects of Water on Nylon

When nylon gets wet, it absorbs water due to its natural hydrophilic properties. This can make the fabric feel damp and heavier, especially noticeable in items like backpacks or outdoor gear. Nylon dries faster than natural fibers like cotton, but proper drying is essential to maintain its quality. In industrial applications, wet nylon parts also require careful drying to preserve performance and durability.

This table illustrates the varying levels of water resistance (measured in hydrostatic head) across different types of nylon fabrics.

Material	Grams/1000m thread	Avg. Fabric density (g/m²)	Water Resistance (Hydrostatic Head)
15D Nylon	1.7	30	2000mm
7D Nylon	0.8	19	1000-2000mm
30D Nylon	3.3	47	4000-5000mm
40D Nylon	4.4	54	5000mm
20D Nylon	2.2	34	3000-4000mm
210D Nylon	23.3	70	15000mm
10D Nylon	1.1	25	1000-2000mm
400D Nylon	44.4	100	20000mm
70D Nylon	7.7	60	10000mm
50D Nylon	5.5	58	8000mm

Nylon Composition

Nylon is derived from petroleum through a chemical process called polymerization. This process creates a long-chain synthetic polymer with repeated amide groups in its molecular structure. Nylon’s ability to resist water is intricately tied to its molecular structure. The presence of robust amide groups enhances its durability but also creates micro-gaps between chains. These gaps, although strengthened by hydrogen bonds, can paradoxically facilitate water penetration over time.

Water Resistance vs. Waterproof

“Water resistance” and “waterproofing” are terms often used interchangeably but hold distinct meanings based on their capabilities regarding water infiltration.

Property	Water-resistant	Waterproof
Water Exposure	Light splashes, brief exposure	Full submersion, prolonged exposure
Durability	Offers some protection	Provides complete protection
Breathability	Generally good	Can be limited
Seams	Typically standard seams	Seams are sealed or taped for added water resistance

Differences between Water-resistant and Waterproof:

• Water-resistant: Provides protection against light splashes and brief exposure to water. Offers good breathability and uses standard seams.
• Waterproof: Offers complete protection against full submersion and prolonged exposure to water. May have limited breathability and utilizes sealed or taped seams for enhanced water resistance.

Nylon and Water Resistance

Nylon, in its pure form, is not waterproof but rather water-resistant. Its water resistance can be attributed to the following factors:

• Hydrophobic Properties: Nylon fibers are hydrophobic, meaning they repel water to some extent. This property is due to the chemical structure of nylon, which does not readily absorb water molecules. However, nylon can still allow water to pass through its weave, especially under prolonged exposure or high pressure.
• Weave and Construction: The water resistance of nylon fabric depends significantly on its weave and construction. Tight weaves and high-denier (thicker) nylon fabrics tend to be more water-resistant than loose weaves or lower-denier versions. The denier indicates the thickness of the fibers, with higher deniers providing greater resistance to water penetration.
• Coatings and Treatments: To enhance nylon’s water resistance, manufacturers often apply coatings such as polyurethane (PU) or silicone. These coatings create a barrier on the fabric surface, significantly improving its ability to repel water. Additionally, treatments like Durable Water Repellent (DWR) can be applied to the nylon fabric to further increase its water-resistant properties.

Waterproof Nylon Products

To create fully waterproof nylon products, manufacturers combine the material with various waterproofing technologies:

• Laminates: Laminating nylon with waterproof membranes, such as Gore-Tex or eVent, creates a fully waterproof barrier. These membranes have microporous structures that block water droplets while allowing water vapor (sweat) to escape, providing breathability and comfort.
• Seam Sealing: Even with waterproof coatings or laminates, seams can be a point of water entry. Seam sealing involves applying a waterproof tape or sealant over the seams to prevent leakage. This process is critical for waterproof performance, particularly in outdoor gear like tents and jackets.
• Welded Construction: In some products, seams are replaced with welded or bonded construction. This technique uses heat or adhesives to bond fabric panels together, eliminating the need for stitching and thus enhancing waterproofing.

Waterproof and Water-Resistance Standards

Water-resistance and waterproofing standards are essential metrics that indicate the level of protection against solid objects and water ingress for various products. Here’s a breakdown of these standards:

Water-Resistance Standards (IP Ratings):

Water-resistance standards are typically designated by the initials IP (Ingress Protection) followed by two digits:

• The first digit indicates protection against solid objects:
• 0: No protection
• 1: Protected against solid objects larger than 50mm
• 2: Protected against solid objects larger than 12.5mm
• …
• 6: Dust-tight (complete protection against dust ingress)
• The second digit indicates protection against water ingress:
• 0: No protection
• 1: Protected against vertically falling drops of water (condensation)
• 2: Protected against vertically falling drops of water when tilted up to 15 degrees
• …
• 8: Protected against continuous immersion in water under specified conditions (typically more than 1 meter depth)

For example, an IP67 rating means the device is dust-tight (6) and can withstand immersion in water up to 1 meter depth for a specified time.

Waterproofing Standards (W Ratings):

Waterproofing standards are denoted by the letter W followed by a number, indicating different levels of water resistance:

• W1: Low-level water resistance, suitable for light rain.
• W2: Medium-level water resistance, capable of withstanding heavy rain and snow.
• W3: High-level water resistance, suitable for heavy rain and showering.
• W4: Very high-level water resistance, effective against seawater, swimming, and shallow diving.
• W5: Absolute water resistance, capable of withstanding seawater, swimming, and deep diving.

How to Test the Waterproofing of Nylon?

When testing the waterproof performance of nylon, standardized methods developed by organizations like ASTM (American Society for Testing and Materials) and ISO (International Organization for Standardization) are commonly employed. These methods aim to simulate real-world conditions (water pressure, spray, humidity) and assess the material’s performance based on key indicators:

1. Hydrostatic Pressure Resistance:
   • Principle: This test measures the ability of nylon fabric to resist water pressure. The fabric is placed in a sealed test apparatus, and water pressure inside is gradually increased until signs of leakage or seepage appear on the fabric.
   • Procedure: By incrementally increasing water pressure, typically measured in millimeters of water column (mm H₂O), the pressure at which the fabric begins to leak is recorded. This value is used to assess the material’s waterproof rating, where a higher value indicates the material can withstand greater static water pressure and has better waterproof performance.
2. Waterproof Rating Test:
   • Principle: This test evaluates how well nylon surfaces resist water under simulated rainfall conditions using a spray.
   • Procedure: A specified pressure and angle spray head are used to simulate rain on the nylon surface. The material’s waterproof performance is graded based on the behavior of water droplets on the surface—whether they bead up and roll off quickly or are absorbed. A higher waterproof rating indicates the material effectively repels water.
3. Water Vapor Transmission Rate (WVTR) Test:
   • Principle: This test assesses the material’s ability to transmit water vapor, indicating its breathability.
   • Procedure: By measuring the amount of water vapor passing through a unit area of the material under controlled conditions, such as applying a specific vapor pressure on one side of the material, the WVTR is determined. Materials with lower WVTR values block liquid water penetration while allowing sweat vapor to escape.

These testing methods not only provide quantitative data on the waterproof performance of nylon but also assist manufacturers and consumers in selecting materials suitable for specific application needs. They ensure that nylon materials deliver reliable waterproof protection in various environmental conditions.

How to Improve the Waterproofing of Nylon?

However, there are various methods to enhance the waterproofing of nylon.

One common approach is applying waterproof coatings, typically composed of materials like silicone, polyurethane, or PVC. These coatings create a protective layer that prevents water from infiltrating the nylon fabric. Techniques such as printing, lamination, or spraying are used to apply these coatings, with the thickness and composition determining the effectiveness of the nylon’s waterproofing capabilities.

Another method involves modifying the molecular structure of nylon through chemical treatments. This process introduces functional groups into the nylon’s structure, altering its properties to enhance water resistance. For instance, incorporating perfluoroalkyl groups can impart a smoother surface, reducing water adhesion. Hydrophobic groups can actively repel water from the nylon’s surface, while fluoropolymer groups form a protective barrier against water penetration.

Nylon Type With Excellent Waterproof Properties

When selecting nylon, several types are renowned for their excellent water resistance:

• Nylon 66: Nylon 66 is one of the most common and widely used types known for its outstanding waterproof performance. Its molecular structure and chemical properties enable it to effectively resist water infiltration.
• Nylon 12: Nylon 12 exhibits excellent water resistance, particularly suitable for applications requiring prolonged exposure to moist environments.
• Nylon 210D: Nylon 210D is a lightweight yet durable nylon, characterized by its higher fiber density and specialized processing, providing excellent waterproof capabilities.
• Nylon 6: Nylon 6 also demonstrates good water resistance, though in some cases it may be slightly inferior to Nylon 66. It is commonly used in applications where moderate moisture protection is needed.
• Nylon 6/66: Nylon 6/66 is a blend of Nylon 6 and Nylon 66, combining the strengths of both types and therefore offering superior waterproof performance compared to pure Nylon 6.

Factors Affecting the Waterproof Performance of Nylon

The water resistance of nylon depends on various factors, including:

• Material Type: Different types of nylon have distinct molecular structures and chemical properties, directly influencing their performance in aquatic environments. Nylon 66 and Nylon 6/66 are generally considered more water-resistant than Nylon 6 due to their tighter and more robust molecular chains.
• Material Thickness: Thicker nylon materials typically provide more physical barriers, effectively blocking water penetration. Thinner nylons may exhibit lower water resistance due to insufficient barrier layers.
• Fiber Structure and Weave Density: Nylon’s water resistance is also influenced by its fiber structure and weave density. A denser and more uniform weave structure reduces the likelihood of water penetration by restricting water flow through gaps between fibers.
• Waterproof Coatings: Applying waterproof coatings is a common method to enhance nylon’s waterproof performance. These coatings, typically made of materials like silicone, polyurethane, or PVC, form a protective layer on the nylon surface. This layer alters the surface chemistry of nylon, increasing its surface tension and causing water to bead up and roll off rather than seep into the fiber structure.
• Climate Conditions: Nylon may perform differently under varying climatic conditions. In hot and humid environments, high temperatures and humidity increase the activity of water molecules, making it easier for them to penetrate through the gaps in nylon fabrics. In such conditions, nylon’s waterproofing performance may be slightly compromised, especially during prolonged exposure to moisture.

Factor	Effect
Temperature & Humidity	Decreases effectiveness over time due to increased water molecule activity
Fabric Treatment	Initially boosts waterproofing; effectiveness diminishes with wear
Thickness & Weave	Tighter weave and thicker fabric improve water resistance
Material Type	Nylon 66 and Nylon 6/66 are more water-resistant than Nylon 6
Fiber Structure	Denser and more uniform structure reduces water penetration
Waterproof Coatings	Enhances waterproof performance by forming a protective layer

These factors collectively determine the effectiveness of nylon in resisting water, ensuring durability and performance in various demanding applications.

Enhancing Nylon Waterproofing Through Post-Processing

Enhancing Nylon Waterproofing with Durable Water Repellent (DWR) Coating is a common method to significantly improve the waterproof capabilities of nylon materials. DWR coating, a chemical treatment, forms a fine waterproof protective layer on the surface of nylon. This layer alters the chemical properties of the nylon surface, increasing its surface tension and causing water to bead up and roll off rather than permeate into the nylon fiber structure.

Prior to applying DWR coating, nylon parts are typically manufactured using methods such as CNC machining or injection molding. These processes enable precise creation of complex shapes and structures required for subsequent waterproofing treatments.

However, it’s important to note that for applications requiring complete waterproofing or submersion, consideration of alternative materials or different waterproofing techniques may be necessary. Materials like polyester (PET) or thermoplastic polyolefin (TPO) offer different waterproofing characteristics and may be more suitable than nylon in specific environmental conditions.

Method of Machining Nylon in Manufacturing

Machining nylon in manufacturing typically involves several key methods and considerations to achieve precise components and products. Here are the common methods used:

Turning

Turning is a common method for cylindrical nylon parts. The nylon material is secured on a rotating fixture on a lathe, and a cutting tool rotates and moves axially along the workpiece to progressively remove excess material, shaping it to the desired dimensions. CNC Turning is suitable for manufacturing shafts, axles, and other rotationally symmetric parts requiring high precision and surface quality.

Milling

Milling is a multi-axis machining method for manufacturing complex shapes and contours in nylon parts. On a milling machine, rotating cutting tools move along multiple axes to cut material from the surface of the nylon workpiece. CNC Milling is used for making grooves, holes, flats, and complex curves with high precision and good surface quality.

Drilling

Drilling is a basic method for machining holes in nylon materials. Using a drill press or CNC drilling machine, a rotating drill bit spins at high speed and applies pressure to gradually cut through the nylon workpiece, forming circular holes. Drilling is suitable for manufacturing mounting holes, through-holes, and other holes requiring precise positioning and dimensions.

Grinding

Grinding is a surface finishing method used to smooth the surface or trim edges of nylon parts. During grinding, a rotating grinding wheel is used to flatten the nylon surface, remove surface irregularities, and provide precise dimensional control. Grinding is crucial for nylon parts requiring high precision fits or surface finish.

Injection Molding

Injection molding is an efficient method for high-volume production of complex nylon parts with intricate details. In an injection molding machine, nylon pellets are melted and injected under high pressure into a mold cavity to form the desired part shape. Injection molding enables highly automated production with precise dimensional control, suitable for automotive parts, electronic enclosures, and industrial components.

3D Printing

3D printing is an additive manufacturing method that builds parts layer by layer using nylon powder or filament. In nylon applications, 3D printing typically involves melting or accumulating layers of nylon material to directly convert design files into solid parts. 3D printing is used for manufacturing personalized products, complex geometries, and customized parts, offering design flexibility and rapid delivery advantages.

Proper machining practices contribute significantly to achieving high-quality nylon components for various industrial and consumer applications.

Designing Waterproof Nylon Parts

In CNC machining, 3D printing, and injection molding processes, enhancing waterproofing features in nylon components can be achieved through specific design considerations.

1. Tilted Surface Design: When designing waterproof nylon components, consider incorporating tilted surfaces to facilitate natural drainage. These inclined surfaces can be oriented towards drainage ports or other designated drainage areas, effectively reducing the time water remains on the component surface and minimizing the risk of water ingress.
2. Integrated Drainage Channels: Integrated drainage channels are another design feature that enhances waterproofing performance. By embedding drainage channels within the nylon component, water flow can be directed to designated drainage points, preventing water accumulation or stagnation inside the component. This design helps to keep the component dry and maximizes the effectiveness of the DWR coating.
3. Application of Sealing Techniques: In situations requiring higher waterproofing performance, the application of sealing techniques is crucial during the design phase. Consider implementing interlocking part structures or integrating gaskets, O-rings, and other sealing components to ensure tight seals at component junctions or seams. This approach effectively reduces the risk of water ingress, especially in environments exposed to moisture or water spray.

Applications of Waterproof Nylon

Waterproof nylon finds diverse applications across various industries due to its ability to resist water infiltration and protect components from moisture-related damage. Here are several key applications:

1. Outdoor Gear and Apparel: Waterproof nylon is extensively used in the manufacturing of outdoor gear such as backpacks, tents, jackets, and footwear. These products require materials that can withstand exposure to rain, snow, and moisture while keeping the contents dry and maintaining comfort for the user.
2. Marine Equipment: In marine environments, where exposure to water is constant, waterproof nylon is used for applications such as boat covers, sails, and marine upholstery. Its resistance to water ensures durability and protection against the elements.
3. Automotive Components: Within the automotive industry, waterproof nylon is utilized for various components such as car covers, seat covers, and interior trims. These applications benefit from nylon’s water resistance, which helps protect the interior of vehicles from spills and moisture.
4. Electronic Device Cases: Waterproof nylon is employed in the manufacturing of cases and covers for electronic devices such as cameras, smartphones, and tablets. These cases provide a protective barrier against water and moisture, safeguarding the sensitive electronics inside.
5. Medical Equipment and Supplies: In the medical field, waterproof nylon is used for items like medical bags, protective covers for equipment, and wheelchair upholstery. The water-resistant properties of nylon help maintain cleanliness and protect sensitive medical instruments and supplies.
6. Aerospace Components: Within aerospace engineering, waterproof nylon is used for components that require moisture resistance, such as insulation blankets, seat covers, and protective covers for sensitive electronic and mechanical systems.

Proper Maintenance of Waterproof Nylon

To ensure the long-term performance and durability of waterproof nylon, proper maintenance is crucial. Firstly, when cleaning, hand wash with cold water and mild detergent, avoiding hot water to prevent damaging the waterproof coating. After washing, air dry the nylon in a cool, well-ventilated area away from direct sunlight and high temperatures. Secondly, avoid using strong cleaners with chlorine or acidic components, as these chemicals can compromise the effectiveness of the waterproof coating. Regularly inspect and maintain waterproof nylon, especially repairing any cracks or worn areas, and use specialized waterproofing products to maintain its waterproof performance. Finally, store waterproof nylon in a dry, clean environment away from moisture and dust to extend its lifespan and keep it in good condition. These simple yet effective methods will help maximize the protection and longevity of waterproof nylon.

Comparison Between Nylon and Polyester

Characteristic	Nylon	Polyester
Industrial Applications	Apparel (yoga wear, innerwear), automotive parts, industrial components	Automotive parts, machinery components, electrical insulations
Durability	More durable, stronger, and stretchier than polyester	Less durable than nylon but more durable than natural fibers
Feel	Softer and smoother	Drier and rougher
Reaction to Water	Absorbs more water	Hydrophobic, quick drying
Reaction to Heat	Cannot be processed under high heat	More durable in high heat
Cost	More expensive	Cheaper
Environmental Impact	More resource-intensive production but higher durability	Less biodegradable
Abrasion Resistance	Performs worse	Performs better
Appearance	Shinier	Duller
Comfort	More breathable, better moisture management	Less breathable in hot conditions

To learn more about the difference between Nylon and Polyester, please read this article: Comparing Nylon and Polyester: Key Differences and Uses

Conclusion

Nylon itself is not inherently waterproof but is naturally water-repellent due to its hydrophobic properties. Its water resistance can be significantly enhanced through treatments and coatings like DWR or laminates. Understanding these factors helps in choosing the right nylon-based products for specific applications requiring protection from water and moisture.

In summary, while nylon provides a good baseline of water resistance, additional treatments and construction methods are necessary for achieving higher levels of waterproofing in various applications.

BOYI offers nylon parts manufacturing and machining services, specializing in utilizing nylon material to produce various components. Nylon, known for its high strength, wear resistance, and chemical corrosion resistance, is ideal for manufacturing parts requiring durability and robustness. Contact us now to get a quote.

FAQ

---

Catalog: Materials Guide