How to Choose and Use Webbing and Accessory Cord

limbing gear is pretty simple when you're bouldering. You've got your personal gear—shoes, harness, and possibly some chalk and a chalk bag. For gym climbing, add a rope, a belay device and a couple of 'biners. When you get into outdoor top-roping, traditional lead climbing or mountaineering, however, you suddenly need more gear. Webbing and accessory cord make up a good part of this bulk.

Webbing and accessory cord are vital links in any climbing set-up. Webbing is typically used to make anchors and runners, and accessory cord is often used for emergency purposes.
Webbing is made of tubular nylon which meets minimum military or climbing specifications. Either is appropriate for climbing.
Accessory cord is made with kernmantle construction similar to climbing rope. Accessory cord is static, however, and does not stretch to absorb the impact of a fall.
Webbing and accessory cord are best cut with a hot knife at the store when you buy them. You can also easily cut and finish the ends at home, if you prefer.
The water knot and the double fisherman's knot are recommended knots for webbing and cord.

Uses for Webbing and Accessory Cord

Webbing is used primarily for anchoring your rope to the rock face or mountain. Sections of webbing are typically tied into loops known as runners (or slings.) Runners are used as links between your rope and the anchors you place in the rock or snow.

Webbing

Runners are available pre-sewn or can be made by tying lengths of webbing into loops. Each type has its advantages. Tied runners can be untied and threaded through natural anchors, or several runners can be tied together into one large runner as needed. Tied runners are also less expensive than sewn runners.

Three sizes of tied runners are typically used:

Singles are used most often to attach your rope to your protection, as long as the route is fairly straight.
Doubles are also used to clip in the rope, but on routes where protection doesn't run up in a straight line. The longer runners allow the rope to remain straighter, which means less drag on the rope and easier leading. Double runners are also frequently used for belay anchors and top-rope anchors.
Triples are used less often, but it's good to have one on your rack on a long climb. They can be very useful for setting up anchors in difficult places.

To make the three sizes of tied runners, cut the following lengths of webbing:

Single runner: 5.5 feet
Double runner: 9.5 feet
Triple runner: 14 feet

Sewn runners are stronger than tied runners because tying knots in webbing reduces its overall strength. Sewn runners are less bulky than tied runners, but they are more expensive. Your budget, climbing style and end use will determine which you select.

Accessory Cord

Both webbing and cord can be used to make runners, although webbing is typically used. Accessory cord has the following additional uses:

Prusik slings—The prusik is a friction knot made by wrapping a smaller-diameter (6 or 7mm) loop of accessory cord through itself around a larger-diameter (9 to 11mm) rope. Its purpose is to grab the rope when weight is put on it, but to slide along the rope when unweighted. Prusik knots are used on "hero loops"—short runners that climbers use as a belay backup so they can assist an injured climber. They are also used on feet and torso prusik slings, which a fallen climber uses as ascenders to get out of a crevasse.
Chock slings—5.5mm Spectra® or Spectra/Kevlar® cord is used for slinging chocks such as Black Diamond hexentrics that don't come with wires already attached.
Cordelette—A cordelette is a long runner constructed of a 16-foot length of 6mm Spectra® cord, tied with a triple fisherman's knot. The extra length of this runner is useful for making an equalized anchor off of multiple pieces of protection or for wrapping around large natural anchors such as trees or boulders.

Construction and Materials

Webbing

Climbing webbing appears to be flat. It actually starts out as a woven tube that is then flattened to form a double thickness. For this reason it is sometimes referred to as tubular nylon webbing. (Note: Flat nylon webbing, used in a variety of camping uses, is a single thickness and is not strong enough for climbing use.)

Climbing webbing comes in two strengths: "mil spec" and Climb-Spec™. Most webbing in the U.S. is made for use in the military. Mil-spec refers to the minimum specifications that the government sets for military webbing used in life support situations. The weaving process gives mil-spec webbing a corduroy-like finish.

Climb-Spec webbing was designed by Blue Water climbing ropes in 1985 specifically to exceed the requirements of standard military-spec webbing. Because a different weaving technique is used, it has a smooth finish. Climb-spec webbing is more abrasion-resistant and stronger than mil-spec webbing. Both kinds of webbing are suitable for climbing.

Webbing is sold in 9/16", 1" and 2" widths. Narrower webbing is lighter-weight and less bulky. 9/16" is used for slinging protection and for making tied runners and quick draws. Wider webbing is more durable, making it great for fixed anchors and top-roping. One-inch webbing is the most commonly used size for tied runners and anchors. Two-inch width is generally used for making substantial anchors for rescue situations.

Accessory Cord

Accessory cord looks like miniature climbing rope. In fact, it's made with the same kernmantle construction—that is, a fiber core (kern) covered with a colorful, braided sheath (mantle). Accessory cord is static (or non-stretchy), whereas climbing rope is dynamic and will stretch to absorb the impact of a fall. Even the largest-diameter accessory cord should never be used as climbing rope.

Accessory cord is typically made of one or a combination of three fibers:

Perlon—This is a European fiber very similar to nylon, often used in accessory cord. Climbers sometimes refer to accessory cord simply as perlon, regardless of the cord's content. Perlon measuring 5mm to7mm is typically used to make prusik slings—loops that are wrapped around the climbing rope to form friction knots.
Spectra®—Spectra, made by Allied Signal Corp., is an extremely strong fiber used in many applications. Climbing cord is just one. Blue Water Titan™ Cord combines the high strength of Spectra fibers in the core with a 100% Caprolan® 2000 nylon (also made by Allied Signal) sheath for durability. In addition to its high strength, Spectra fiber is resistant to damage by repeated flexing. The extra strength of Spectra cord is desirable for chock slings, but its slippery texture makes it less appropriate for prusiks.
Kevlar®—This incredibly strong, cut-resistant fiber made by DuPont is most well-known for its use in bulletproof vests. Kevlar by itself does not withstand repeated flexing, so it is usually combined with Spectra in accessory cord. It is best used for making chock slings.

Cutting

It's easiest to have your REI climbing salesperson cut your webbing or cord into individual lengths for you when you buy it. When ordering online, order each length separately so that the ends of your cord and webbing will be cut and finished with a hot knife, preventing unraveling.

If you prefer to buy one long piece and cut the sections yourself, it's fairly easy to do so. You'll need some sharp scissors, a heat source, such as a lighter or candle flame, and an old butter knife.

Webbing—Cut with scissors and melt the end in the flame. Use the knife to smooth down the melted edges. (Caution: The knife handle can get hot, too, so wrap something around it!)

Accessory Cord—Cut about an inch longer than you need. Work a half inch of the core out of the sheath and cut it off. Smooth the sheath back and melt it into a smooth, hard "cap" on the end of the cord. This method of finishing will allow the cord to fit into the holes drilled in hexentrics. To get a clean cut on Spectra® cord, it may be necessary to use cable cutters.

Tying

Webbing

Webbing is typically tied with a water knot, also known as a ring bend. Webbing often has one solid-color side and one side with a dashed line running down the center. These markings help to match up the webbing when making knots. To make a water knot, first make an overhand knot in one end of the webbing. Then with the other end, retrace the knot backwards, matching solid color to solid color, or dotted line to dotted line.

Accessory Cord

Accessory cord is usually tied into runners with a fisherman's knot. For perlon or nylon a double-wrapped fisherman's knot is used. A triple fisherman's knot is recommended on Spectra and Kevlar due to their slippery textures. The extra wrap minimizes any chance of the knot slipping.

NOTE:Make sure you leave at least a 2 inch tail on each end and check your knots occasionally—they can loosen up with time.

Marking

Only so many colors of webbing and cord are made each year, and yours might start to look like everyone else's at the crags. Mark your gear so you're sure to get it back at the end of the climb. On runners, write your initials and the date you made them with marker. You can use a marker for accessory cord, but it might be easier to use colored electrician's tape on the round surface. Be sure to mark the tails of your runners and prusik loops, rather than the working surfaces.

Retirement

Just like climbing rope, accessory cord and webbing eventually need to be retired. Keep track of when you make your runners and retire them after each season of hard climbing, or every other year if you don't use them that often. Be sure to inspect your webbing and cord before each climb for any signs of damage and retire any suspect runners. This is also a good time to check all your knots. Note: Both Kevlar and Spectra become stiff and weakened by exposure to UV radiation and should be retired after 100 days of use.