Nylon vs Dacron

The 2 Best Types of Rappel Ropes (Nylon, Dacron and Other Considerations)

The following guide was made by rappellers, for rappellers in order to grasp the differences in the rope products available on the market today, in order to make a prudent decision on what to pull the trigger on . You should  get into the habit of reading specs put out by the manufacturers, but with a grain of salt (always as a conservative reading). Thus, we will observe the minimal readings to help guide you along your way to understanding the properties of these rappel  ropes.

Ropes Materials Mentioned…

 I.D.ModelFeaturesCompare Prices
#11/2" X 150' Blue Double Braided Nylon Rope6" Climbing° Nylon Double Braid

°Spliceable, repels dirt, mildew and rot

°5800lb Tensile
Compare Prices
#21/2 in X 50 ft Black Polyester Double Braided RPolyester Double Braid Rope, DomesticMiami Cordage° High strength low stretch

° Torque balanced construction

°Ideal wet/dry abrasion resistance
Compare Prices
#3EVERSTRONG Polyethylene rope Black with blue tracerEVERSTRONG Polyethylene rope Black with blue tracer° 55% Dacron 45% polyethylene

° Great chemical resistance

°Multiple uses and applications
Compare Prices
#4New England Rope New England HRC X 50 ftNew England Rope Nomex w Vectran kern° Heat resistance of 800 deg F.


°50ft increments
Compare Prices
#5SGT KNOTS Twisted Polypropylene Rope (1/4 inch) SGT KNOTS Twisted Polypropylene Rope (1/4 inch - 3/4 inch) ° Total Enviromental resistance


°Long Lasting
Compare Prices
#63/8'' x 75 ft. Braided Fiberglass RopeFiberglass Rope by Sandhill° Able to handle continuous temperatures up to 1000 degree F

° 3/8'' x 75 ft. Braided
Compare Prices
#7upont Kevlar Braided Line,3mm900lb 100% Dupont Kevlar Braided Line,3mm by Spearit °16 strand braid

°twisted core with a clear synthetic finish for added stiffness

° UV resistant

°Tensile: 900lb with 3'' Diameter
Compare Prices

Again, to prevent you from making overestimations of the materials, we have taken the minimum readings on specs (temperature ratings, strength capacities, duration etc.) into account. We also are going to take a biased approach (especially in the eyes of beginners) to say we recommend sticking with nylon ropes for rappelling, unless you are very familiar with the properties and are using the rope for special situations.

nylon rope

Pictured: Rappeler using dual nylon on rig

Extreme caution should be taken when using dacron polyester, Fortrel polyester, polyethylene, polypropylene, nomex and other materials to rappel with. To get the exact spec data on these products, get in touch with the manufacturer and do your research! It will ultimately save your life.

Rappelling with nylon rope

Back in the 30’s Nylon 66 was the first ever synthetic that went widespread in rope manufacturing. Rappellers around the world use it because of its ability to handle cuts and bruises made by sharp obstacles such as cliff edges and rough terrain. It is also viewed as the most practical rope material and can be used in many different applications. The synthetic ropes made today are usually Type N-66 or 6-nylon. In different parts of the world, (Europe and other parts) type 6 nylon is interchanged with perlon. Type 6 is very similar to 66 but its properties are slightly different. So..

  • Type 6 has a melting point of 383° F and T-66 melts at 446° F. Type 6 has a little more durability than T-66 but these temperature ratings should be considered.
  • Loss of strength begins to occur for T-6 at steady temps of 175°whereas T-66 begins to lose durability at 270° F. Keep in mind some of the T-66’s out there have been known to lose small amounts of vitality degradation at consistent temperatures of 140° F.

On the flipside, nylon ropes tend to actually strengthen at lower temperatures (example: when rappelling in the cold weather) and have been on full display  with no damage at temperatures as low as -90° F. Keep in mind that a great amount of TLC is needed for the ropes when rappelling at these temperatures.

Factors for storing nylon rope

store rope, storing rope, storing nylon, storing nylon rope

Pictured: Store Nylon In a dry space away from chemicals

When you are storing your rope in excellent of conditions, the rope will degrade very very slowly. Keep in mind..

  • Strength will be lost if you are storing your rope in areas where UV and radiation levels are on the high side.
  • Mold, must, rot and other forms of mildew cannot effect nylon rope in any way (huge advantage for storing purposes). However, metals that come in contact with nylon such as iron that has been rusted or steel equipment will lessen nylons strength overtime. That is why it is extremely important to stow rope away from these kind of metals.
  • Nylon is resistant to most of your everyday chemical applicants, but will get completely ruined  by other forms of highly concentrated chemicals (bleaches, acids, etc). Natural oils such as pig fat lard, can lessen the durability of nylon.
  • When soaked in water, nylon has a propensity to absorb up to 8-10% into its kern strands. H20 can act to split up the H bonds in the fiber molecules , resulting in up to 14-18% in loss of vitality in the nylon.  You will also notice shrinkage and rigidity in the nylon when it is saturated in water.

Dye may be used to color nylon in order to increase its lifespan. Reason being is certain colors work better than others in blocking out sunlight (UV). The dye itself can have no ill effect on durability of the nylon unless the dye is blended in while the rope is being manufactured. So you can see that durability depends on how the nylon is processed when it is being made.

cutting rope, cutting line

Pictured: Poly rope abrasions do happen

Rappelling with Dacron (Polyester) rope- Be cautious

Polyester, or Dacron/Fortrel brands are made with low flexion. Many Static rappel ropes use polyester as the material for both the mantel and kern. These fibers are able to only about 10%-14% as opposed to nylon which has a flex capacity of about 15-21%+. Breaking durability vary for polyester, depending on how the manufacturer goes by composing the product. Many polys have the same conservative break capacity as nylon line does.

Dacron as well as Fortrel have been known to really resist against shock loads and will not flex as well as nylon which is why they are used in Static lines made for long distance rappelling and not short rappels where bounce may occur. You can really hurt yourself if the rope goes one way you go the opposite way during a fall with the laws of physics and biology in mind. So..

  • Polyester has a melting point of 470° F but has been known to handle 212° F for 19-20 consecutive days without losing any durability at all. It is able to handle low temperatures just as with nylon.
  • You can be less worried about storing polyester around chemicals but there are a few, like ammonia and battery acid, to steer clear from storing these types of ropes next to. There have been instances where storying poly ropes near and around certain chemicals have actually enhanced the ropes durability levels.
  • Polyester repels UV rays and radiation better than nylon
  • As far as water absorption is concerned, poly only takes in about 1% of water into its fibers and does not rot, must or rot.  

Rappelling with other rope considerations (Be extremely cautious)

When is it ok to rappel with:

Polyethylene- When considering rappel rope made of polyethylene, one should consider where they are doing most of their rappelling. If you are a rappelling expert and want to try your hand at rappelling waterfalls, then polyethylene would make a considerable amount of sense, seeing as they do the best job staying buoyant and rappelling water. It’s strength capacity is about 1/2 of what a nylon or polyester rope can endure, therefore please be very careful when using this rope. Other properties of polyethylene to consider:

  • Polyethylene has a much lower melting point, at 248° F
  • It does really well against rotting out, must or molding
  • It does not absorb water at all so there are no saturation levels to consider
  • Polyethylene does not do well with UV rays as it will be destroyed very quickly with sun exposure (This can be avoided depending on which UV inhibitors the manufacture used in the process of making the rope)
  • Resists radiation completely so it is the choice of rope during military rescue ops brought on by nuclear incidences
  • High resistance to acids and other highly concentrated acids


Pictured: Rappeler using a Nomex composite rope

Nomex– The basic purpose of these types of ropes is to repel fire and high temperatures. Nomex simply does not melt but does begin to disintegrate at temperatures over 700° F+. It too, has 1/2 the durability capacity of a nylon or polyester rope. It also have very comparable properties when reacting with similar chemicals. It flexes better than nylon and polyester (different capacities at different weights)

Polypropylene– The chemical properties are akin to what is offered with polyethylene. It is highly resistant to chemical intrusion and actually absorbs less water than glass would. Polypropylene rope is buoyant and we would rappel with it around terrain surrounded by water at low pitches. Again stay cautious when using. It is half as durable as nylon and decomposes rapidly with UV exposure. Again, it all depends on what the manufacture did to coat it with the necessary UV resistant applications to assume it is usable when rappelling in the sun. Polypropylene has a melting point of 311° F.  We would use it to rappel before we used Polyethylene because it does have better elastic properties then the latter.

Fiberglass line– You may not have known that some line comprise of fiberglass materials. These ropes are mainly used  in commercial scaffolding, firefighter tactics and tactical warfare in areas with high amounts of radiation. It comes in handy when there is a high propensity of heat of even temperatures as high as 945°F. Fiberglass line is also the choice when having to repel uv degradation as well as toxic chemicals. The knock on them is that they don’t have much elongation properties, making them very limited when it comes to recreational rappelling.

This rope is hardly supple and can literally crack when knotted incorrectly or spliced so be extremely careful with it. We recommend this rope for the occupations mentioned above as well as only for emergency purposes only. If you are utilizing this type of rope, make sure to go slower than usual when rappelling. It is important to have a nice rhythm when rappelling, but with fiberglass line you need to stay at an intentionally slower speed in your descent. Also, ease into any stops along the way. While recommend using a spool-like descender, make sure it doesn’t bend the rope at a sharp angle. These descenders are made to stop from kinking and bending the rope.


Pictured: Rappeller using a special Kevlar composite rope near the Nyiragongo Volcano

Kevlar– By far, one of the strongest materials ever made, kevlar rope is the toughest out there. It is more durable then even steel and more rigid than even glass. Kevlar can be found in a lot of different applications such as ship hulls and body armour.  Kevlar rope typically comes in smaller diameters (large diameters are hard to make and not really needed). These lines are great for short distant pitches while rappelling. Kevlar is similar to Nomex in that it will not melt but will disintegrate at 800 °F. On the flipside, it has been tested to handle temperatures hovering around -330°F with no ill effects to the rope itself.

Water will not affect kevlar’s durability capacity, and can handle chemical nuclear warfare when put to the test. However, certain acids like hydrofluoric acid can lead to degradation of Kevlar rope if consistently exposed. Kevlar does not do well with UV unless the necessary protection of resin is applied.

We do not recommend kevlar rope while rappelling long distance pitches or normal recreational use because of its inability to elongate. Kevlar fibers can only stretch to 3% longer than normal before shredding. When tying off kevlar, it can weaken up to 35%-65% it’s normal durability capacity due to energy alteration. When using kevlar, make sure your anchors can handle high shock capacity. Use big descenders when using kevlar rope.  Kevlar fibers will actually damage themselves if the descender used is not large enough because of misshaping of the line.


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