How Does Sunlight and Moisture Affect Nylon Webbing, and How Can You Protect It?

Invisible enemies of strong straps

You might have inspected a strap that looked perfectly fine only to have it snap under load. Unlike obvious cuts or fraying, the damage caused by sun and water happens quietly. Product designers and outdoor enthusiasts often assume that nylon webbing’s strength is eternal, overlooking how quickly ultraviolet (UV) rays and moisture erode its integrity. When a harness or tie-down fails in the field, it can lead to serious injury, property damage, and costly delays.

Understanding how the environment degrades nylon webbing allows you to choose materials wisely and implement practical maintenance measures. This article explains the science behind UV and moisture damage, signs to watch for, and proactive steps manufacturers and users can take to extend the life of their webbing.

How UV Radiation Weakens Nylon Webbing

Nylon webbing is durable because its polymer chains are tightly bonded. UV radiation from sunlight gradually breaks those bonds, making the fibers brittle and reducing tensile strength. Studies reported by textile engineers show that:

• Moderate sun exposure (around six months) can reduce strength by 20–30 %, even if the webbing still looks intact.
• Prolonged exposure (three years or more) may result in 50–60 % strength loss. The webbing becomes brittle, discolored, and prone to cracking.
• Darker colors fare better because they absorb and dissipate UV energy more evenly. Lighter colors and neon shades tend to degrade faster.

Early signs of UV damage include fading, stiffness, micro-cracking, and frayed edges. These subtle cues warrant immediate replacement in safety-critical applications.

Moisture, mildew, and strength loss

Unlike polyester, nylon absorbs 4–10 % of its weight in water. Saturated nylon loses about 10–20 % of its strength because water molecules disrupt the hydrogen bonds that give nylon its rigidity. Fortunately, this reduction is temporary: the fibers recover once dried. However, repeated wet-dry cycles and prolonged immersion can lead to:

• Swelling and stretching – the webbing may elongate by 2 % when wet, affecting fit and tension.
• Fungal growth – damp, dirty webbing becomes susceptible to mildew and mold, which can weaken fibers and create unpleasant odors.
• Chemical degradation – chlorine, acids, or alkaline cleaners accelerate breakdown, particularly in pool or marine environments.

Strategies to Minimize Environmental Damage

You can’t control the sun or rain, but you can reduce their impact by following best practices:

• Choose UV-treated webbing. Many manufacturers add UV inhibitors during the dyeing process or weave high-density fabrics that absorb less radiation. Look for products labeled as UV-resistant or designed for outdoor use.
• Select darker colors or mix materials. Black, navy, and forest green webbing withstand sunlight better. In areas of high sun exposure, pair nylon with UV-stable fibers, such as polyester, to improve longevity.
• Apply protective coatings. Spray-on UV protectants or fabric coatings can add an extra layer of defense against radiation and moisture. Reapply as directed in the product instructions.
• Store away from sunlight. Encourage end users to keep gear out of direct sunlight when not in use. Storing harnesses and straps inside equipment bags or under covers dramatically slows degradation.
• Allow wet straps to dry thoroughly. After exposure to rain or immersion, dry the webbing at room temperature. Avoid highheat sources that could melt or warp the fibers.

Inspection and replacement guidelines

Regular inspection is the most effective way to catch UV or moisture damage before it leads to failure. Experts recommend:

• Monthly visual checks for items exposed daily to sunlight or used in marine environments.
• Quarterly or bi-annual inspections for seasonal equipment or gear that sees intermittent use.
• Annual strength tests for safety harnesses, rescue slings, and other critical products. Replace the webbing immediately if the test indicates a significant reduction in strength.

During inspections, note any fading, stiffness, brittleness, or mildew. If there’s uncertainty about remaining strength, retire the strap. Keep records of purchase dates, usage conditions, and inspection results to establish reliable replacement cycles.

Prolong Your Investment with Proactive Care for Nylon Webbing

Sunlight and moisture are relentless adversaries of nylon webbing. By recognizing how UV radiation and water affect polymer bonds, selecting UV-treated and darker webbing, and implementing proper storage, cleaning, and inspection routines, you can dramatically extend the life of your straps.

A few simple steps today will prevent unexpected failures tomorrow and ensure your equipment remains safe and dependable in all weather conditions.

Related Reading

• Abrasion Resistance in Nylon Webbing: Make it Measurable, Then Make it Last
• The Four Most Common Industries Buying Wholesale Nylon Webbing
• Which is the Strongest: Nylon Webbing, Polyester, or Polypropylene?