If your supplier can’t give you a clear answer on nylon vs polyester for fall-arrest lanyards, here’s the reality: for most OEM designs, polyester is the safer and more predictable choice. Its low elongation, minimal moisture absorption, and stronger long-term outdoor stability make it far easier to pass drop tests and maintain consistent performance across batches.
Nylon only makes sense when your design intentionally relies on higher energy absorption and controlled stretch. Otherwise, its higher moisture uptake and faster UV degradation introduce unnecessary variability into a safety-critical system.
Read on to see how each fiber performs under real fall-arrest loading, so you can specify the correct material, avoid supplier pushback, and ensure your lanyard webbing passes testing on the first round.
Webbing manufacturing expert with 15+ years of experience helping product developers build high-performance straps for industrial, medical, and outdoor use.
The performance factors that matter most in fall-arrest lanyards are predictable elongation, strength retention after repeated loading, and outdoor durability. These three directly affect arrest distance, consistency during testing, and long-term safety.
If you’ve been getting mixed supplier recommendations, it’s because most webbing shops compare nylon and polyester using plain tensile charts — not the real stresses a lanyard faces. What actually determines success is how the fiber behaves under shock loads, how much its elongation drifts after cycling, and how well it holds strength in UV, humidity, and daily abrasion against metal hardware.
Ignoring these factors is the main reason teams end up with:
Evaluating webbing using dynamic loading behavior, environmental stability, and friction performance will tell you far more about material suitability than any “nylon vs polyester strength” chart.
Design Takeaway:
Base your material decision on elongation control, post-cycle stability, and outdoor performance — not on raw strength numbers. If your testing failures involve inconsistent elongation or unpredictable arrest distance, you’re likely using the wrong fiber for fall-arrest conditions.
Polyester maintains strength and elongation far more consistently after cyclic loading because it absorbs less moisture and remains dimensionally stable outdoors. Nylon tends to drift after repeated loads due to higher water absorption and sensitivity to humidity and temperature.
If your supplier only gave you single-pull tensile data, that’s why your samples may pass the first test but fail after cycling. Cyclic fatigue exposes problems that aren’t visible in a one-time load test, and polyester’s molecular structure handles this far more predictably.
Nylon can still work — but only if your design intentionally relies on its higher stretch and you can tolerate variation after cycling. Otherwise, it often leads to issues like:
If you’ve experienced drop-test failures that don’t match the initial tensile results, this is usually why.
Design Takeaway:
For reliable post-cycle performance, start with polyester. Use nylon only when your design intentionally relies on higher energy absorption — and be prepared to manage variation after repeated loading.
Polyester gives far more predictable elongation under fall-arrest loads because its stretch stays stable across humidity, temperature, and repeated cycles. Nylon can work, but its elongation changes enough day-to-day to cause inconsistent arrest-distance results.
This is the issue behind nearly every “we passed yesterday but failed today” drop-test story. Nylon’s elongation can shift noticeably with only a small change in humidity. A supplier who only provides dry tensile data won’t see this — and you won’t notice it until the lanyard fails a controlled drop test or exceeds the maximum arrest distance.
A reliable webbing supplier will always measure:
If your supplier can’t provide these numbers, they’re guessing — and you’ll see the consequences in testing.
Design Takeaway:
If your arrest-distance tolerance is tight (and most are), choose polyester. If your supplier cannot show pre-cycle and post-cycle elongation data, treat that as a red flag — predictable elongation is the backbone of fall-arrest safety.
Get quick guidance on whether nylon or polyester fits your design
Polyester holds strength better under long-term UV exposure. Nylon loses strength faster when exposed to sunlight, which shortens safe service life and causes unexpected strength loss during re-testing.
If you’ve ever seen webbing get fuzzy, stiff, or brittle after outdoor use, that’s nylon degrading. The problem is that UV damage doesn’t always show visually. A sample can look normal but still fail strength retention by a wide margin. Suppliers who only provide “new condition” tensile reports won’t warn you about this.
A competent supplier should be able to show:
If your supplier avoids UV-retention data or says “all fibers weaken the same outdoors,” that’s your sign to switch immediately — that’s not how fall-arrest materials behave.
Design Takeaway:
If your lanyard sees sunlight regularly, use polyester by default. If your supplier cannot provide UV-retention numbers (even approximate), assume they do not understand outdoor durability for safety-critical webbing.
Moisture affects nylon dramatically — it absorbs water, elongates more, and temporarily loses strength. Polyester practically ignores moisture, keeping its performance steady in any weather.
If you’ve ever had a sample pass dry but fail after sitting overnight, this is the explanation. Nylon can absorb several percent of its weight in moisture, enough to soften the structure and add extra stretch. That change may seem small on paper, but in a fall-arrest system, even a few extra millimeters of elongation can push you out of spec.
A webbing supplier who understands fall-arrest should provide:
If your supplier dismisses moisture as “not a big factor,” that’s exactly why their nylon samples behave unpredictably.
Design Takeaway:
If your lanyard will ever encounter rain, humidity, sweat, or outdoor storage, start with polyester. Nylon only makes sense when you intentionally rely on its energy absorption and your supplier can prove its wet-vs-dry performance with real data.
Chemical exposure is one of those issues suppliers gloss over, but it shows up fast once a lanyard is used around machinery. Polyester simply survives chemicals better. Oils, cleaning agents, hydraulic fluids — polyester shrugs them off with minor surface effects. Nylon doesn’t. Once nylon absorbs oils or reacts with certain solutions, its strength starts sliding quietly, long before the webbing looks worn.
If you’ve ever pulled a lanyard off a job site and wondered why it “feels softer,” that’s the chemical interaction changing the internal structure. And if your supplier never asks where the lanyard will be used, that’s another sign they aren’t thinking about this.
A good supplier checks:
Design Takeaway:
If chemicals are part of the environment even occasionally, choose polyester first. Nylon only works when the product stays clean, dry, and away from industrial fluids — a rare situation in fall-arrest use.
Temperature swings expose a behavior difference most people don’t expect. Nylon “moves” with the weather — softer, stretchier in heat; noticeably stiffer in the cold. Polyester stays closer to its baseline, which means your drop-test numbers stay closer too.
This is why early-morning testing and afternoon testing sometimes don’t match when nylon is involved. Suppliers who focus only on room-temperature reporting never catch this, and they certainly don’t warn you about it. If your team has ever scratched their head at inconsistent arrest-distance numbers, temperature may be the quiet culprit.
What separates a knowledgeable supplier from a casual one is simple:
Design Takeaway:
If your lanyard will be used or tested in varying climates — or if consistency matters more than energy absorption — polyester is the safer default. Nylon demands tighter environmental control and more testing time to verify behavior.
Abrasion is the one category where nylon usually wins. Constant movement across metal anchors or adjusters wears nylon down slower. Polyester’s surface fibers tend to fuzz sooner under repeated rubbing, even if the underlying structure is still strong.
But here’s where many teams make the wrong call: abrasion isn’t the only durability factor. A lanyard that handles hardware movement beautifully but fails UV retention or absorbs moisture unpredictably still fails the bigger safety requirement. Suppliers that oversell nylon for abrasion often ignore those trade-offs.
The real question is:
Where does your lanyard actually fail first — at the hardware point, or in environmental exposure?
Good suppliers will ask that before recommending anything.
Look for a supplier who can show:
Design Takeaway:
Choose nylon when hardware friction is the clear, proven failure point. Choose polyester when outdoor exposure, humidity, or chemical durability pose the bigger risk — even if nylon technically abrades better on metal.
If your lanyard is going to live outdoors, predictability matters more than anything else. Over months of sun, rain, and temperature swings, polyester settles into a steady decline, while nylon’s behavior jumps around depending on what the environment throws at it.
Polyester slowly loses strength in a fairly linear way — you can plan around that. Nylon fades quicker under UV, absorbs moisture on humid days, dries out differently depending on temperature, and becomes more brittle over time. The result? Every batch ages a little differently, and every test report tells a slightly different story.
A supplier who understands outdoor aging will never say “both materials handle weather fine.” They’ll reference:
And they’ll warn you when nylon simply isn’t worth the maintenance burden for a safety-critical product.
Design Takeaway:
If long-term outdoor stability matters, go with polyester. Nylon requires too many assumptions and too much environmental control to age predictably.
Batch consistency is where polyester quietly wins. Even small lot-to-lot changes — humidity during weaving, drying conditions, storage environment — hit nylon harder. That means two rolls of nylon webbing produced months apart can test differently, even if the supplier swears the specs never changed.
Polyester is much less temperamental. You won’t see big swings in elongation, moisture content, or stiffness between batches. This is why many fall-arrest manufacturers eventually switch to polyester: not because nylon fails the first test, but because nylon fails the repeat test.
A supplier who takes consistency seriously will track more than just tensile strength. They’ll measure:
You’d be surprised how many suppliers don’t check any of this.
Design Takeaway:
If you don’t want to fight “Batch A passed, Batch B failed,” polyester is simply easier to control, test, and repeat in production.
Switching fibers often changes the quote — but not always in the way teams expect. Polyester is usually more stable in cost, especially across large orders, because its raw-material supply chain is broader and less affected by moisture-based processing adjustments. Nylon pricing can swing more, partly due to post-processing, partly due to environmental conditioning requirements.
But here’s the part suppliers rarely say out loud: nylon’s hidden costs show up in testing and re-testing. More moisture conditioning, more variable test results, more scrap when elongation shifts — the “cheaper per meter” price disappears quickly once you factor in failure rates.
Good suppliers will break down:
If your supplier only talks about the per-meter number, they’re avoiding the rest of the conversation.
Design Takeaway:
Polyester generally gives you a more predictable overall cost — not just material price, but testing, scrap, and repeatability. Nylon only stays economical when your design needs the extra stretch and you’re ready to handle the variability.
This is where many sourcing conversations go sideways. A supplier can only recommend the right material if they know how the lanyard will actually be used — not just width, thickness, and color. The biggest mistakes come from sending a drawing without context and assuming the supplier “knows what fall-arrest needs.” Most don’t.
What a good supplier really needs is simple:
When suppliers don’t ask these questions, they default to whatever material they run most often. That’s how nylon gets recommended for environments where it has no chance of behaving consistently.
Design Takeaway:
Share how the lanyard will be used, not just the dimensions. The more context you give, the easier it is to choose between nylon’s stretch and polyester’s stability — and avoid the back-and-forth that slows your quoting process.
Most fall-arrest failures come from suppliers who treat nylon and polyester as interchangeable. A material-focused partner prevents that. Upload your lanyard drawing and requirements — we’ll assess the fiber choice, flag risks, and return a manufacturability review and quote within 24 hours.
Yes. Even minor faults like skipped yarns or uneven edges can create weak points that only show up during shock loading. General-purpose webbing tolerances do not apply here — fall-arrest webbing requires strict defect rejection to avoid unpredictable failure modes.
Yes. Coatings can improve abrasion or water resistance, but they can also stiffen the webbing or alter elongation. Any coating applied to fall-arrest webbing must be validated for cracking, UV stability, and retained strength under bending. Never assume a coating behaves neutrally in safety-critical use.
Most safety-grade webbings can reliably achieve ±0.5–1.0 mm width tolerance. Anything tighter requires modern looms, consistent yarn tension, and humidity control. If a supplier hesitates to commit to a specific tolerance, they likely cannot hold it consistently across production.
Many shops avoid fall-arrest projects because they lack controlled testing environments, traceable batch processes, or the ability to verify dynamic-load performance. When a supplier declines, it usually reflects internal capability gaps — not a flaw in your specification.
A qualified supplier should provide tensile data, multi-load elongation results, post-cycle strength retention, and basic UV or moisture behavior information. Lack of documentation usually signals insufficient process control — and increases the risk of test failures or certification delays.
Strength variation usually comes from differences in test conditioning, load rates, and sample preparation. Some suppliers test dry webbing only, while others precondition to humidity standards. If results vary widely, it’s a sign your supplier isn’t following consistent testing methods — a major risk for fall-arrest applications.