Aluminum deposits on rope

[Adam Byrd]

Hi everyone,

I have heard that that the aluminum deposits left on ropes by aluminum brake bars are harmful to the rope. Is this true? If so, what is the mechanism by which the rope is harmed by the aluminum?

[Mark620]

Besides the discoloration of the rope,
The deposits left on the rope turns into aluminum Oxide (Al2O3).
Aluminum Oxide is the abrasive in (most) sandpaper.

[Scott McCrea]

Aluminum Oxide is the abrasive in (most) sandpaper.

So, what grit size is the stuff found on ropes? I bet it's so small, it's more likely to polish the rope than abrade it.

[Adam Byrd]

Ok, that makes sense that all of those tiny Aluminum Oxide particles could abrade the rope, however, I haven't found anything exlicitly stating that. Has anyone come across any serious studies or articles on this subject?

[Mark620]

So, what grit size is the stuff found on ropes? I bet it's so small, it's more likely to polish the rope than abrade it.

Small, verry small...etc.

Besides, unless the rope is in motion, no damage would occur.

[hank moon]

Ok, that makes sense that all of those tiny Aluminum Oxide particles could abrade the rope, however, I haven't found anything exlicitly stating that. Has anyone come across any serious studies or articles on this subject?

I think all those tiny AL oxide particles abrade the rope far less than sand, mud, rock abrasion, etc. Far as I know, rope damage from AL friction device use is a myth. A pretty prevalent one, too. Kinda like the one about damage from stepping on the rope. There has been at least one published study about that one (see 12 and 13, below). In my experience, damage from some other source (rockfall, poor edge protection, etc.) will get a rope long before anything else. I think The AL oxide myth was invented by folks who didn't like their ropes gettin' all gray and dingy...



Report (winter 97/98 ) from the president of the UIAA safety commission, Pitt Schubert. His considerable experience of investigating dynamic climbing ropes produced some of the following findings....

1. Ropes cannot break in the tie in knot, or at the running belay.

2. Any rope can break when loaded over a sharp edge. It is not possible to produce a rope that is strong enough not to break when loaded over a sharp edge, however, the maximum chance for survival is with a new rope.

3. Use of twin rope has cut down on breakages.

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

5. Car battery acid damages ropes and cannot visibly be detected. In Germany there have been at three known cases where this has happened.

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

7. Coke (the drinking variety) was not found to compromise the strength of a rope.

8. Autan (insect repellent), although damaging to plastic, was not found to damage ropes...in fact strength was slightly increased.

9. Sea water did not affect the strength of ropes.

10. Ropes soaked overnight in urine had their strength reduced by 30%, however, only when loaded over a sharp edge would this matter.

11. UV radiation does NOT damage ropes. Nylon is UV stabilised and only the colour will be lost.

12. Standing on a rope loaded over a right-angled metal edge with three times body weight did not reduce a ropes strength.

13. Standing on a rope in the snow with crampons did no damage. Neither did standing on it on rock with a 75kg body weight.In a further test Crampon points were forced right through the rope with no strength reduction/damage occurring!

14. The strength of frozen and wet ropes was reduced,but again, unless the rope is loaded over a sharp edge it would not matter.

15. The suggested lifespan of 10 years which has been given for ropes is to help the user determine lifespan . However, after contact with ICI it was found that although after 10 years there was a measurable degradation in nylon (not just in ropes, but all nylon textiles) ageing itself would not cause a rope to break, unless it was loaded over a sharp edge.

16. Top roping damaged ropes, but the damage was visible and could be felt, as was damage from stonefall.

[Squirrel Girl]

The deposits left on the rope turns into aluminum Oxide (Al2O3).
Aluminum Oxide is the abrasive in (most) sandpaper.

I don't think that's true. The abrasive in sand paper is CORUNDUM (or garnet). But that's not what aluminum metal oxidizes to. I'll bet it's hydrated, but I'm not a metalurgist, and don't know huge amounts about that end of it. Corundum is a high temperature, high pressure mineral, if I recall correctly. Thermodynamically, it wouldn't naturally form here at earth surface temps and pressures.

Besides the discoloration of the rope,

That's the real reason people who don't take their ropes into anything but open air pits don't want people using aluminum on their ropes. They have this cleanliness fetish.

[Caver]

quote]That's the real reason people who don't take their ropes into anything but open air pits don't want people using aluminum on their ropes. They have this cleanliness fetish.[/quote]

I have never been concerned about using AL bars on my ropes, except for the ugly black marks it makes on my coveralls. After all, AL bars was the only thing used for years, until stainless came along and I do not recall many people dying or very many ropes breaking because of the use of AL. I am also very safety concious, but think things like sand, rough edges, and the like are more damaging to ropes than the minute amount of AL deposited on ropes while rappelling.

Just an opinion

[Cheryl Jones]

Hey, we always figured that was "status" black on a rope. It meant lots of vertical caving and experience. Didn't hurt nuthin' and looked very cool. Like the status marks across the arms and back of our jean jackets from arm rappels. They went along with the "status grooves" in our brake bars and on the cams and shells of our Gibbs ascenders. I even had a status groove in my G-shock watch band for years from an arm rappel.


Cheryl

[Lava]

The abrasive in sand paper is CORUNDUM (or garnet).

Actually, corundum is ruby/sapphire, not garnet. Sorry to be a picky bastard!

[Squirrel Girl]

The abrasive in sand paper is CORUNDUM (or garnet).

Actually, corundum is ruby/sapphire, not garnet. Sorry to be a picky bastard!

Actually, ruby and sapphires are types of corundum.

And, the "or garnet" MEANT to say that there can be garnet sandpaper. So sandpaper can be made from corundum. Or sandpaper can be made from garnet.

That's for pointing that out. Wouldn't want people being confused.

[hunter]

Hey Hank,
Do you have a link or reference for the report you quoted? I would be very interested in reading it.

Hunter

[hank moon]

Hey Hank,
Do you have a link or reference for the report you quoted? I would be very interested in reading it.

Working on it. I got the info in my original post from

http://www.pete-smith.co.uk/ropewear.htm

A summary of the "step on rope" report (along with other interesting stuff) is here:

http://www.alpineclubofcanada.ca/servic ... index.html

Note that the reports concern the performance of dynamic climbing ropes, which are made of 100% nylon. I think the results can be probably be used (within reason) to make some good predictions about static and low-stretch ropes of similar materials and construction. Use the head, not the knee! I have not read the original reports (except the summary of "step on" on the ACC site), but should be able to get the source material from friends in Europe...will post back if/when I do.

[hunter]

Hank,
Thanks for the info! The gas/diesal is what I'm really curious about. I've always kind of worried about keeping a gas can in the truck with all my gear.
I'm kind of amazed by the crampon thing. Maybe because most crampons have points but not really sharp edges they seperate fibers in a rope but don't cut them.

Hunter

[cob]

It is all a matter of abrasion. SG: Al oxide IS one of the many things used for sand paper... garnet is another. That said I never worried about AL bars on my ropes. I agree the particles are so fine... give me a break.

When it comes to walking on ropes... better not on mine. Your boots may be as soft as a babies butt... but the chert underneath it can be fractured sharper than a surgeons scalpel (I don't give a RAT'S ASS about some study that says crampons don't hurt rope... I KNOW CHERT DOES!!!!!!) and I HATE cutting off the last 20-25 feet of rope.

My opinion... and several others as well.

tom