Why Slings And Harnesses Age Even Unused

Metal climbing gear is retired when it looks damaged. Textile gear has to be retired on a timetable, because the deterioration that matters leaves nothing visible behind.

Ultraviolet is the main enemy

Nylon and polyester fibres degrade under ultraviolet light. Photons break polymer chains, and each break slightly reduces the load the fibre can carry.

The damage is cumulative and irreversible. A sling left permanently at a sunny belay accumulates far more exposure than one that lives inside a pack.

The visible effects lag well behind the strength loss. Fading suggests exposure has occurred, but a sling can be badly weakened while still looking almost new.

Chemicals do quiet damage

Acids attack nylon particularly effectively, and the exposure is rarely dramatic. Battery acid in a car boot, or fumes in a garage where equipment is stored, is enough.

Because the affected fibres do not change colour or texture reliably, contamination cannot be inspected for. Suspicion of exposure is treated as grounds for retirement.

Salt, grit and dirt work mechanically instead. Fine particles work between fibres and abrade them internally every time the sling flexes under load.

Loading leaves a history

Each significant load stretches fibres slightly, and they do not recover fully. A rope or sling that has held falls has less energy absorption left than the specification suggests.

Knots concentrate this. A rope loaded hard with a knot in it carries the greatest stress at the knot, which is why some parties cut and retire that section.

Dynamic ropes are also softened by repeated use, and a rope that feels furry and stretchy has already changed its behaviour from new.

What the published lifespans mean

Manufacturers publish a maximum life from date of manufacture for unused textile equipment, and a shorter one for gear in regular use. Both are conservative estimates rather than guarantees.

The date of manufacture, not the date of purchase, starts the clock. Equipment can sit in a shop or a warehouse for a long time before anyone owns it.

Products carry that date on a label or a woven marker. Once it is illegible the item has effectively lost its provenance, which is itself grounds for retirement.

Why second-hand textiles are a different question

A used sling carries an unknown history. There is no way to establish what it was exposed to, how it was stored, or what loads it has taken.

Since the damaging processes are invisible, no inspection resolves that uncertainty. This is the specific reason experienced climbers draw a hard line at buying used soft goods.

Manufacturer inspection guidance for each product, and instruction from someone qualified, are what should govern retirement decisions rather than how a piece of webbing looks.