Animal Damage: Dyneema vs. Nylon/Polyester

What I refer to as "Dyneema" is Samson Ropes Amsteel "Blue," a kind of UHMWPE.

I have to be careful about leaving nylon and polyester ropes on the floor of my house, as my cat finds it satisfying to chew on such ropes. Once the cat tried to chew an Amsteel cord, and gave up; she broke no threads, and after that ignored Amsteel. I guess there is a reason cut-proof protective wear, and bear bags, are made from Dyneema or a similar UHMWPE.

I have seen lots of nylon slings that were nearly chewed through, sometimes just months after they were placed. The creepy problem is that the animal damage usually occurs behind a rock or brush, out-of-sight. Often the damage is right by the water knot in tubular nylon. I can imagine people with sweaty, salty hands -- maybe scented by lunch or sunscreen -- spending more "hands-on" time by the water knot. The animals want relative safety while they eat, so tend to concentrate on the webbing that is out-of-sight. On the other hand, most climbers, when judging if a webbing sling is still good, seem to focus on the the area in the sun; after all, they are looking for the stiffness and fading from UV damage. I always check older slings end-to-end; this can be very difficult when they are threaded through tight cracks. I often put bizarre labels on slings, just to see if people really check them end-to-end. If someone complains the sling has some defect -- say lack of equalization -- but can't tell what the label said, I can be pretty sure that person is more concerned with climbing lore, versus safety.

It is very hard to design animal damage tests; given the randomness of animal-sling encounters, there should be many, many tests, standardized for sling strength and typical usage. The slings must be well-affixed to the rock, or animals will pull them into the open. They must be out-of-the-way enough to avoid encounters with humans, who will surely mess with them. Some should be buried partly in shallow sand; and there should be a very similar range of environments (for the materials to be compared) on the average. Technically, it may be illegal to place these on government land, especially if the food smell is interpreted as "baiting." The peanut-butter-salt mixture will apeal to omnivores and even some herbivores, which may be interpreted as "big game."

Bear bags are sometimes tested with actual bears in zoos; but that is a more dramatic and immediate animal-food encounter. I suggest that the slings could be tested in animal pens on a farm or caged area. Pig pens or mink farms might work best, but even sheep or cattle will chew ropes. I know of several backwoods Death Valley cabins that could provide lots of rodent exposure if the slings were hidden in the crawl space; but that would surely infuriate the park service. We have lots of old mining cabins in Nevada; they are full of trash, and clearly rodent-infested, and pretty much off the radar of the gub'mint.

Pics by Harlan W S,
2019-2022

Nylon webbing, on rap anchors in the Grand Canyon, is often chewed by rodents within a month of placement. (pic from M. Cressman)	in 2019, I attached loops of polyester and dyneema cord to a weighted steel cable and placed the cable in a small cave. The cords had the same diameter, and were smeared with peanut butter. A few days later, the 2 black polyester loops were nearly chewed through, while the 2 yellow dyneema loops were largely intact.	But I figured a fairer test would be with equal-strength nylon tubular and dyneema slings -- 2400 lb 5/8" nylon tubular webbng vs. 2500 lb 1/8" dyneema. Both were smeared with peanut butter. The nylon was damaged, the dyneema barely touched, but critters dragged the test into the open after a day.
My next test used 25mm 4000 lb climbspec webbing against 5/32" 4000 lb Dyneema. I soaked linguine in peanut butter, then put the pasta inside each (only one piece fit in the dyneema, 3 in the nylon). The nylon was heavily chewed, but I couldn't say the "target" food was comparable.	So in Oct 2022, I set up what I thought would be a 3-year test. This time the Dyneema was precoated with maxijacket (a UV protection I now put on all semi-permanent UHMWPE slings). I alternated 2 nylon with 2 Dyneema slings (using 2 quicklinks and 2 girth hitches to join), and coated both with a mix of peanut butter and salt.	After just 3 weeks, the brown nylon webbing (previous image) and black nylon webbing were severed near the knots. The Dyneema had very minor damage, which I think was actually from it being pulled against the abrasive rocks as the animals chewed the nylon. Arrows show where nylon was severed. Maybe the knots are just easier for the critters to grab.
The minor damage to Dyneema, near girth hitch	Dyneema connected via quicklink was undamaged.	Lastly, please distinguish climber "Dyneema," which is often 40% nylon by weight (the colored strips above), from Amsteel, which is pure Dyneema with a small amount of urethane and dye..