Aluminum deposits on rope

[cob]

4. There have been no known rope failures in sport climbing

6.Petrol and Diesel do not damage ropes, even when left overnight to soak! WD40 caused no damage either.

.

On #4: Huh? I know of several... what do they mean by this?

#6: Amazing. I never would have thought...

Thanx for the link... I will go there soon (tonite!)

[NZcaver]

Interesting topic. From the first time I was introduced to rappelling and vertical caving, taking care of ropes was always high on the priority list.

Hank's post about rope testing is eye-opening. It's fascinating to me that climbing ropes were found to have negligible strength loss after extended exposure to UV light, or after being bathed in petroleum and other supposedly harmful chemicals. Damage from battery acid was no surprise to me, but the urine test was something I hadn't thought of. I wonder if that differs by species?

I think I'll file that information away under "things that make you go hmmm," and continue avoiding all chemicals, acids, urine, storing ropes in the sun, and people who stomp on them. The problem with stepping on rope is not about crushing it under body weight - it's all those little sharp rock particles potentially getting driven into the weave and scissoring through the fibers over time. At least that's what I've always been told, and from reading what Cob posted I'm not the only one to have these concerns.

As for the original point of discussion - I was once told that aluminum particles degrade rope strength, and I held that belief for a long time. Keeping an open mind, I now realize that this probably isn't true. However, a significant aluminum coating will affect the handling of ropes and in my opinion, not in a good way. That black, glazed, powdery substance is not what I prefer to rappel or ascend on.

I prefer to use descenders with stainless steel surfaces, or a combination of stainless and aluminum (like the Petzl Stop). I can tolerate aluminum devices too, provided they are linear. I prefer to avoid aluminum figure-8 type descenders, especially on single rope, as they seem to have a more prolific aluminum transfer effect. Plus they twist the rope, but that's a whole other topic. Descent speed is another factor that appears to affect the way the aluminum is transferred onto the rope, and figure-8s move faster than most other descenders.

I have to disagree with Cheryl's earlier post. I don't think having black aluminum on the rope is a status symbol that looks cool and doesn't hurt nuthin'. The grooves in the descender and so forth - fair enough. That's normal and irreversible wear-and-tear. But you consider having dirty rope as a status symbol? You might find washing it occasionally helps to remove some of the black (and mud), possibly improves it's handling, and cuts down on those black status symbols all over your clothing and other people's.

OK - I can't say that I wash all my gear after every trip, but I do better than some cavers I've met. There's always a few that never seem to wash anything - they just shake the dirt off each time. That's a great way to cross-contaminate caves by introducing bacteria from one to another, but I guess that's a whole other topic too. Granted it may not be such a large concern in every caving region.

So in my opinion, aluminum on or in ropes is something to be avoided from more of a handling perspective than a safety one. Feel free to agree, disagree, or try to convince me otherwise.

[Phil Winkler]

Good comments and I agree with you. I thas always been a given that caving/climbing ropes never break. They may get cut, smashed, abraded, but will not simply break. The same thought is used with lines on boats. They don't break ever when used for the purpose for which they were intended.

That's an important distinction, too. Also, lines on boats are very similar to caving ropes; braided, laid, dynamic or stiff (for halyards and sheets) and, unlike caving ropes, marine lines are exposed to the sun day in and day out. I knew many years ago that nylon was unaffected by UV light. I'd bet I have some lines on my boat that are 30 years old and they still are completely serviceable.

I don't like dirty ropes either from aluminum or from mud. Washing in a clothes washer with Tide followed by the dryer and fabric softener results in a faster rope (for the first 1 or 2 rappels, anyway) and one that will last longer as much of the grit gets washed out of the mantel and core.

[Squirrel Girl]

It is all a matter of abrasion. SG: Al oxide IS one of the many things used for sand paper... garnet is another.

Again, sandpaper can be made from corundum which is a form of aluminum oxide. But that does not mean that the black stuff that forms from the oxidation of aluminum metal is corundum.

Let me give a different example. Pure carbon. Diamonds make fantastic abrasive. If they weren't so darn expensive, there would probably be a LOT of sandpaper made of diamond. Graphite. Same chemical formula: C as diamond. BUT! It's a LUBRICANT! Same formula, different structure, entirely different properties.

I know a little about corundum. I know next to nothing about the black stuff that forms from metallic aluminum that oxidizes. However, I would bet a small amount of money that it is *not* corundum. For all I can gather from this thread, the black oxidized aluminum could likewise be a lubricant. I doubt it, or it'd probably marketed that way. But unless someone presents a study that shows weakening of a rope rappelled on with aluminum bars versus steel bars, I won't believe that a little bit of black on a rope makes an iota of difference in terms of strength.

The ore for aluminum is bauxite, a soft material made of boehmite, gibbsite, and diaspore. Those are all aluminum oxyhydroxides. My guess is the black is something like these.

I tried doing some google searching on a aluminum oxide abrasives. It was hard to get the exact info I was looking for. However:
http://www.answers.com/topic/aluminium-oxide
talks about alumina abrasives. It seems the abrasives must be manufactured by extreme heating the aluminum or, for instance, the anodizing process which is done by running an electric current. It doesn't seem that earth surface pressures and temps naturally forms a hard aluminum oxide compound.

When compared with a rope that gets used in a cave where there's quartz silt ground into the nylon, I'd be more worried about the caved rope. Yet how many cavers say, "I won't use that rope--it's been used before in a cave!"

[ian mckenzie]

Yet how many cavers say, "I won't use that rope--it's been used before in a cave!"

The armchair variety might...

[Squirrel Girl]

Yet how many cavers say, "I won't use that rope--it's been used before in a cave!"

The armchair variety might...

I think that rope of mine that Tropicalbats lent you without my permission has been in a cave before!

[ian mckenzie]

Well it was so clean when I returned it you'd never know...

[Squirrel Girl]

Well it was so clean when I returned it you'd never know...

Indeed. It was beautifully clean when returned. I thank you from the bottom of my black -- aluminum oxide coated -- heart! :lol:

[Mark620]

Obviously, the black stuff on the rope from aluminum bars is aluminum and aluminum oxidizes when exposed to oxygen. The particles are very small and would pose no problems for the rope other than the dark Grey color.

[Caver]

How long does it actually take for the minute particles to get through the sheath and touch the core? weeks? months? I have seen people rappelling on ropes so black that they looked like they were made of steel. slick and shiny looking. They might have been safe, but wouldn't that amount of aluminum cause a severe loss of friction?

just curious

James

[Scott McCrea]

Here's a picture of what else can happen when you climb a dirty rope. :lol: That's me, second from the left, with the big black stripe up my shirt. Got it from climbing 650' of 'fairly clean' rope at Whitesides. It was my rope and I know that out of a hundred or so rappels on it, only a half dozen or so were on aluminum bars. Aluminum rides don't bother me. Besides, as Cheryl says, makes for a heck of a 'status stripe!'

[hank moon]

The problem with stepping on rope is not about crushing it under body weight - it's all those little sharp rock particles potentially getting driven into the weave and scissoring through the fibers over time. At least that's what I've always been told,

y'know, i've been told that too...but I have never seen any evidence to support it. It's no problem for 5 cavers to rap on a muddy rope, the mud potentially loaded with tiny, scissory crystals, said mud being continuously squeegeed between bars, bobbins, whathaveyou...and the rope. But...if one of those people steps on the rope with a muddy boot - watch out! hee hee...

[NZcaver]

Hank - you have a valid point. Here's how I look at it.

When I buy a caving rope I expect to ascend/descend on it, get mud and crud on it, and periodically clean it. Getting debris on or in the rope is part of that. It's not something I deliberately seek out, but it's not some I can avoid either - unless I don't take my ropes caving. :(

But I can probably avoid having myself and others step on the rope. Will it damage the rope more than normal dirty caving use? Maybe, maybe not. Will I throw the rope away if someone accidentally does? No. Will I try not to include it as a factor in the eventual decline of my rope? If possible, yes.

I'll probably avoid bathing the rope in Petroleum too, even if studies conclusively show it does no harm. I guess I'm saying that normal caving use will always include some abuse, but why add unnecessary factors that may cause more damage if you can avoid them instead?

And Scott - nice shot of you with the status stripe! You look pretty happy. The other four guys all look happy too, but none of them have their stripes visible. Did they climb a cleaner rope, or is there something I'm missing? I'm guessing the black on your shirt was caused by more influences that just a half-dozen "aluminum descents" on your rope. Bet that shirt never came clean, but I'll wager that you don't really care because you wear it as a status symbol anyway.

[Cheryl Jones]

I'll probably avoid bathing the rope in Petroleum too, even if studies conclusively show it does no harm.

If you're a carbide caver, a petroleum bath could result in a lot of damage to your rope! And probably do some damage to your eyelashes as well.

But what a great photo op as the flame races up the rope in a deep pit....

Cheryl

[hank moon]

But I can probably avoid having myself and others step on the rope. Will it damage the rope more than normal dirty caving use? Maybe, maybe not. Will I throw the rope away if someone accidentally does? No. Will I try not to include it as a factor in the eventual decline of my rope? If possible, yes.

That's cool...and reasonable. Been around folks that really "freak out" if the rope gets stepped on. No need for that...s'all I'm trying to say. 8)