washing ropes

Just to be clear – there is (likely) no gain of strength with gasoline. Soaking your rope in gasoline to pick up another percentage of strength is unlikely to be a good long-term strategy.

When testing fibrous things, like ropes, there is a fairly large natural variation. It would take 100s of tests of each condition to even out the statistical variation. Therefore, consider each number stated to be +/- 5%, so one, two or three samples of gasoline soaked ropes with an average of +1.8%, means it had no measureable effect.

Also worth noting is that ropes are made of several different fibers, so the nylon/nylon ropes tests (wasn’t it?) do not necessarily apply to polyester ropes, to polyester/spectra ropes, to polyester/technora/spectra ropes, etc.

The thing to carry away from this is: batteries BAD!, bleach BAD!, otherwise – no too many worries, maybe.

YMMV

Tom

— In Yahoo Canyons Group, Paul wrote: > Thanks Bo and James for the great responses on washing ropes and > effects of various chemicals. Tom your comments made a lot of sense > also, but I was put off a bit by your insinuation that I should not > canyoneer through vats of grease. But after reading Bo’s note on the > beneficial effects of oil, I feel better again. I just won’t wash the > rope afterwards anymore!

Seriously though, it is interesting to see a loss of strength with water > saturation and a slight gain in strength with oil and gasoline. Perhaps > related to lubrication and friction? I do recall that water saturation > has a major adverse affect on dynamic properties by filling up the space > between fibers and preventing them from moving properly.

Water saturation does have the benefit of keeping the rap device a lot > cooler.

Paul >

A climbing (dynamic) rope is built with a (relatively) thin sheath and a lot of core strands. On a climbing rope, the strength of the rope is balanced between the core (60%) and the sheath(40%).

In many cases, a climbing rope wears out by losing it’s dynamic properties. It becomes stiffer, making it (eventually) dangerous to climb on, as even small falls can generate large forces if the rope is stiff.

The fear of climbers is that dirt and sand will work their way into the core of the rope and starting messing with the core strands, thus weakening the rope.

Caving and Canyoneering ropes, on the other hand, pack as much material as possible into the sheath. Especially the small ropes. Canyoneering ropes wear out by developing core shots, by having one or more fibers on the sheath cut (usually by rubbing over a sharp edge under tension). Once one fiber is cut all the way through, the core shot tends to enlarge with each subsequent loading of the rope, eventually (if it gets that far) going all the way around and the sheath seperates, revealing the core.

So while the core in useful in a canyoneering rope, it does not provide the strength we actually use. Then again, I would not want my rope not to have one!

If you put a kern-mantle (core-sheath) rope on a pull-test machine, the core and sheath break seperately – First the sheath, then the core – because the two parts stretch rather differently. It will vary from rope to rope, but what I remember (as if that is realiable) is that the sheath breaks at say 4000 lbs, then the load drops down to 1000 lbs and builds back up till the sheath breaks at 5000 lbs. What kind of rope? I don’t remember. The conclusion I reached is that both the core and sheath are good for say 4000 lbs, but they function independently. This means that after you cut through the sheath, the rope will still be strong (until the core strands cut), just not be very usable.

(Although, some load is taken by the core while the sheath is stretching out to failure).

I’m not sure how the rope loses strength from dirt. Yes, there is a general thought that a rope with dirt on it will slowly abrade the sheath fibers. Certainly a wet, sandy rope does a good job of cutting through soft sandstone, aluminum rap rings, belay biners and rappel devices. Sand and dirt certainly can’t be good for your rope.

I’m not that familiar with larger-diameter caving ropes, which might have relatively larger cores.

Maybe I can dig up some better test data on the ropes I am now distributing.

Tom

— In Yahoo Canyons Group, jef levin wrote: > Tom, > I’d appreciate a little more explanation of what your > trying to say here. I was referring primarily to loss > of strength due to dirty ropes. How is it that > canyoneers use the sheath more than cavers or > climbers? My understanding is that most of the > strength of a rope comes from the core. > – Jef

> That would be all well and good if we were climbers

and thought the

core was the real important part, but we are

canyoneers, and we use

the sheath. The core? Just fibers to hold the

sheath apart.

Tom

That would be all well and good if we were climbers and thought the core was the real important part, but we are canyoneers, and we use the sheath. The core? Just fibers to hold the sheath apart.

Tom

— In Yahoo Canyons Group, jef levin wrote: > I don’t mean to imply that ropes don’t need to be > washed occassionally, but I’ve cut open many well used > and dirty caving/climbing ropes over the years (prior > to retiring them) and have been amazed at how little > dirt actually makes it past the sheath. > – Jef

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