3-strand — Twisted constructions are abrasion resistant but a poor choice for climbing due to their bumpy surface and tendency to rotate (unwind) under tension. Good as natural crotch rigging line.
Solid braid — Made up of 12 large strands, arborist-grade solid braid lines are woven tight to keep a round shape under tension. Less tendency to twist than other braided lines. Good for climbing or rigging.
Hollow braid — Another 12-strand construction, but woven with considerably less tension, leaving the center loose enough to accommodate an easy splice. Good for slings and fixed lines, but not for climbing or rigging due to snagging and picking when run over a rough surface.
16-strand — This abrasion-resistant rope construction presents a thick mantle (cover) around a small interior core bundle that helps keep the rope round under tension and makes it easy to tie. The thick mantle provides most of this popular climbing line’s strength.
Double braid — This braid inside a braid remains round under tension even when running over pulleys and brake drums. Generally core and cover share equal load. Best for rigging duties, a tight version offers greater dirt resistance when natural crotch rigging, and a loose version is more spliceable and best for block and tackle use.
Kernmantle — The mantle (cover) of this rope is woven tight to provide protection for the load-bearing core (up to 70 percent) strands, which are not woven (parallel). Core strands can also be twisted like a slinky to add elasticity, providing manufacturers a lot of flexibility to manipulate the finished product based on intended use. Good for a wide range of duties. Arborist climbing lines of this construction are considered “cover dependent kernmantles.”
The circles below represent diameters in 1-millimeter increments in the range of ropes from throwline up to rigging line. For those still struggling with metric relationships, we thought the visual might help.
Polyester — A synthetic polymer having lower stretch and higher tenacity and abrasion resistance than its close cousin Nylon. Melting point: 480 degrees Fahrenheit.
Nylon — A synthetic polymer with more stretch and with less abrasion resistance than polyester. Rarely used in arborist-grade lines. Melting point: 460 degrees Fahrenheit.
Polyolefin — A monofilament sometimes used to bring a rope’s weight down. Melting point: 260 degrees.
Aramid — Family of fibers including Technora, Kevlar and Nomex that, pound for pound, are five-times stronger than steel and have high abrasion and heat resistance. They have poor ultra violet (UV) radiation resistance, and are mildly self-abrasive. Charring point: 900 degrees Fahrenheit.
Ultra High Molecular Weight Polyethylene (HMPE) — Includes Spectra and Dyneema. This lightweight fiber has super high strength and abrasion resistance but at a very low melting point. Good for use where heat friction is not involved. Melting point: 297 degrees Fahrenheit.
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