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majid_sabet


Aug 29, 2012, 12:33 PM
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The effect of humidity and rope storage
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Short term or long term effect of humidity on ropes

Has any one done any study on the topic ?



MS


JimTitt


Aug 29, 2012, 2:13 PM
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Yes.


majid_sabet


Aug 29, 2012, 2:29 PM
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JimTitt wrote:
Yes.

good,bad or ugly ?


JimTitt


Aug 30, 2012, 10:42 AM
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Well the general opinion seems to be that while the strength of nylon is effected by humidity the treatments used in manufacture, the built-in strength reserves and limited levels of exposure to extreme humidity mean for climbing gear it is irrelevant. The record of broken ropes seems to bear this out. There is something by the CAI out there but their conclusion is as above.


jowybyo


Aug 30, 2012, 11:07 AM
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I may be wrong but isn't the decreased tensile strength in nylon from moisture absorption? If it's dried out it should return to near full strength, no? If so, that would make long term storage at high relative humidity irrelevant if the rope is allowed to dry prior to use?


JimTitt


Aug 30, 2012, 11:19 AM
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Well yes but since generations of climbers have been climbing and falling on wet ropes and climbing in humid areas without drying their ropes and they donīt break then it canīt be much of an issue anyway. To "dry" a rope which has been long-term stored in humid conditions would take ages since the moisture uptake is very much slower than most people realise.


patto


Aug 30, 2012, 11:23 AM
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JimTitt wrote:
Well yes but since generations of climbers have been climbing and falling on wet ropes and climbing in humid areas without drying their ropes and they donīt break then it canīt be much of an issue anyway. To "dry" a rope which has been long-term stored in humid conditions would take ages since the moisture uptake is very much slower than most people realise.

A wet rope is significantly weaker than a dry rope due to the internal pressure effects.

Nylon isn't affected by water so humidity really isn't a problem long term.


jowybyo


Aug 30, 2012, 11:34 AM
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I'm pretty sure we are splitting hair at this point, at least as applied to climbing. But, nylon's material properties including modulus, glass transition temperature, and tensile strength are affect by it's moisture content. This is true at the filament level.


JimTitt


Aug 30, 2012, 3:47 PM
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patto wrote:
JimTitt wrote:
Well yes but since generations of climbers have been climbing and falling on wet ropes and climbing in humid areas without drying their ropes and they donīt break then it canīt be much of an issue anyway. To "dry" a rope which has been long-term stored in humid conditions would take ages since the moisture uptake is very much slower than most people realise.

A wet rope is significantly weaker than a dry rope due to the internal pressure effects.

Nylon isn't affected by water so humidity really isn't a problem long term.

Rubbish, nylon starts to effectively de-polymerise and weaken. This has been known since the 1930īs when removing all the water was the breakthrough in creating a usable form of nylon.


curt


Aug 30, 2012, 4:27 PM
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JimTitt wrote:
patto wrote:
JimTitt wrote:
Well yes but since generations of climbers have been climbing and falling on wet ropes and climbing in humid areas without drying their ropes and they donīt break then it canīt be much of an issue anyway. To "dry" a rope which has been long-term stored in humid conditions would take ages since the moisture uptake is very much slower than most people realise.

A wet rope is significantly weaker than a dry rope due to the internal pressure effects.

Nylon isn't affected by water so humidity really isn't a problem long term.

Rubbish, nylon starts to effectively de-polymerise and weaken. This has been known since the 1930īs when removing all the water was the breakthrough in creating a usable form of nylon.

Probably something patto read on the internet somewhere and assumed it must be true.

Curt


USnavy


Aug 30, 2012, 9:09 PM
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Humidity increases the rate at which the rope swells, that is for sure.


patto


Aug 31, 2012, 12:00 AM
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JimTitt wrote:
Rubbish, nylon starts to effectively de-polymerise and weaken.
From my understanding this does not occur at room temperature or typical rope exposure temperatures. On further research various sources refer to the strength of nylon returning once it drys.

I'm no expert here, I may be wrong. But that is my understanding.


JimTitt


Aug 31, 2012, 12:42 AM
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patto wrote:

A wet rope is significantly weaker than a dry rope due to the internal pressure effects.

Nylon isn't affected by water so humidity really isn't a problem long term.

The first part of your post is rubbish as the reduction in strength is nothing to do with internal pressure(whatever that means anyway).

The second part of your post is rubbish because nylon is affected by water, the loss of strength being not quite proportional to the amount of water absorbed.
Nylon is hydrophilic in that there are free connections on the molecules for water molecules to attatch to the nylon molecules. The water molecules bind onto the nylon molecules and move them apart causing the material to swell, the increased distance between the molecules weakens the secondary forces holding them together which weakens the material. This process is reversible and occurs at normal ambient conditions.

Your climbing rope is changing size and strength on a daily basis depending on temperature and humidity which is why ropes have to be conditioned to a specific temperature and moisture content before testing.


knudenoggin


Sep 4, 2012, 2:00 PM
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JimTitt wrote:
patto wrote:

A wet rope is significantly weaker than a dry rope due to the internal pressure effects.

Nylon isn't affected by water so humidity really isn't a problem long term.

The first part of your post is rubbish as the reduction in strength is nothing to do with internal pressure(whatever that means anyway).

Assume that what is meant is friction between fibres,
then his statement is on target --as far as extended usage
in large ropes of mooring or towing systems is concerned.
In reply to:
[accident analysis]
... 12-inch circ. [~3.75" dia] 8-strand nylon 6.6 rope stretchers ...
The ropes were made up into grommets with soft eyes.
[think dogbone]
... would give a new dry strength of about 215 tonnes
and a wet strength of about 190 tonnes [88%].
...
Tests showed that the ropes would lose about 4.4%
of strength per day in this kind of towing service,
due to internal cyclic abrasion of wet nylon.

[Handbook of fibre rope technology]

Re the storage issue & long-term effects,
I recall mention of "hydrolysis", but find now one assertion that
pure water hydrolysis has too small an effect to matter.

In reply to:
Your climbing rope is changing size and strength on a daily basis depending on temperature and humidity which is why ropes have to be conditioned to a specific temperature and moisture content before testing.

How much can that really matter, in likely conditions (not extremes)?
If it's much, then that raises the question of interpretation of such
testing for practice --for those varied conditions of usage. (Here
I'm thinking not of precipitation but just relative humidity and temps.)
(Waiting for the UIAA-approved litmus lines which turn red when
they're unsafe for more than abseils ..., green otherwise. Smile )


*kN*


Kinobi


Sep 29, 2012, 4:54 AM
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Yes, CAI (Italian Alpine Club) did some tests.
One: http://www.caimateriali.org/index.php?id=16
Two: http://www.caimateriali.org/index.php?id=21

To explain it is very simply: Yes water significantly weaken a rope.
Is this "weaker" that much relevant to climbers? May be.
If the rope is really soaked, and used (may be abused), it's significantly weaker that I would suggest to take care to try not to fall on it.
If it's iced, even worse.

With the use with "half" ropes, once you could fall on only one rope, it's better to be carefull. Again if ropes aver very wet or soaked.

Still... the ropes (albeit the diameters tested were "fat") tested on Dodero had, in my opinion, a significant strenght, that, unless I have a very worn and abused rope and a belayer to crucify, I will personally not bother too much.
But for stats based climbers, they loose at least/around 50% of their strenght.
Greetings from Italy.
E


USnavy


Sep 29, 2012, 9:03 AM
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Kinobi wrote:
If the rope is really soaked, and used (may be abused), it's significantly weaker that I would suggest to take care to try not to fall on it.
If it's iced, even worse.
I have taken a few big whippers on completely soaked ropes and guess what, the rope did not break (big surprise). Ice climbers have been taking falls on wet and icy ropes for ages. When is the last time you have heard of a rope breaking because it was wet? It's never happened. Majid is just trolling us trying to get info on a topic he never actually partakes in.


Kinobi


Sep 29, 2012, 9:30 AM
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USnavy wrote:
I have taken a few big whippers on completely soaked ropes and guess what, the rope did not break (big surprise). Ice climbers have been taking falls on wet and icy ropes for ages. When is the last time you have heard of a rope breaking because it was wet? It's never happened. Majid is just trolling us trying to get info on a topic he never actually partakes in.
In reply to:


Kinobi wrote:
Still... the ropes (albeit the diameters tested were "fat") tested on Dodero had, in my opinion, a significant strenght, that, unless I have a very worn and abused rope and a belayer to crucify, I will personally not bother too much.


Marylandclimber


Sep 30, 2012, 7:54 AM
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And aren't dry ropes treated to keep out water and moisture?


marc801


Sep 30, 2012, 8:55 AM
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Marylandclimber wrote:
And aren't dry ropes treated to keep out water and moisture?
Yes, but it actually wears off quite quickly, especially if the rope is used for rock climbing. Some manufacturers advertise that each strand is dry treated, and these may resist water absorption a bit better, but it still doesn't really keep the rope dry.

Dry treatments are meant to reduce the absorption of water to keep the weight of the wet rope down and to try to prevent it from freezing into unmanageable wire. It's not done for strength when wet or to achieve longer storage times.

Dry treatment for rock climbing ropes is an unnecessary extra expense imho.


iknowfear


Sep 30, 2012, 9:13 AM
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marc801 wrote:
Marylandclimber wrote:
And aren't dry ropes treated to keep out water and moisture?
Yes, but it actually wears off quite quickly, especially if the rope is used for rock climbing. Some manufacturers advertise that each strand is dry treated, and these may resist water absorption a bit better, but it still doesn't really keep the rope dry.

Dry treatments are meant to reduce the absorption of water to keep the weight of the wet rope down and to try to prevent it from freezing into unmanageable wire. It's not done for strength when wet or to achieve longer storage times.

Dry treatment for rock climbing ropes is an unnecessary extra expense imho.

not totally unnecessary. It keeps dirt off, too.


marc801


Sep 30, 2012, 9:33 AM
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iknowfear wrote:
not totally unnecessary. It keeps dirt off, too.
Minimally, at best, until it wears off after 10 climbs. Again, it doesn't justify the expense.


TradEddie


Oct 1, 2012, 8:25 AM
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I just realized this advantage of a dry rope a few days ago, so strange to see it 'confirmed'. I bought my first ever non-dry rope last year, and despite very, very little use, it is now significantly dirtier than any previous rope I have owned.

TE


USnavy


Oct 1, 2012, 10:47 AM
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TradEddie wrote:
I just realized this advantage of a dry rope a few days ago, so strange to see it 'confirmed'. I bought my first ever non-dry rope last year, and despite very, very little use, it is now significantly dirtier than any previous rope I have owned.

TE
I own 11 ropes right now, 7 are dry ropes, the others are not. All of them are equally dirty in reference to the type of use and amount of use they have been seeing. The dry coating put onto ropes is mostly a gimmick. It works great when the rope is brand new, but with minimal use even the best dry coatings will wear off very quickly.


(This post was edited by USnavy on Oct 1, 2012, 10:48 AM)


ptlong2


Oct 1, 2012, 11:19 AM
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USnavy wrote:
The dry coating put onto ropes is mostly a gimmick. It works great when the rope is brand new, but with minimal use even the best dry coatings will wear off very quickly.

In drop tests dry treated ropes consistently hold more falls than otherwise identical non-dry ropes. There is also evidence that they are more durable.


knudenoggin


Oct 11, 2012, 11:21 AM
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ptlong2 wrote:
USnavy wrote:
The dry coating put onto ropes is mostly a gimmick. It works great when the rope is brand new, but with minimal use even the best dry coatings will wear off very quickly.

In drop tests dry treated ropes consistently hold more falls than otherwise identical non-dry ropes. There is also evidence that they are more durable.

But surely you mean "in drop tests with new ropes",
and USN's remark concerns ropes that are used --and that
would be the majority of ropes of concern. Are there tests of
used ropes that show a general superiority to the dry coating?
(Of course, gauging some wear index and also matching the make
of rope --and thereby the exact dry treatment (do they differ?)--
could be a challenge.)

(I recall the cute summation of a UIAA study done long ago:
that the claims for dry treatments don't hold water;
as, alas, the ropes themselves do.)
Tongue

*kN*

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