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rtsteed
Sep 25, 2011, 5:56 PM
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I have heard conflicting reports, ranging wildly from only bleaching the color out of a rope to severe strength reduction after time. So what is the truth?
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caughtinside
Sep 25, 2011, 6:03 PM
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It degrades the nylon. This reduces the strength, as well as bleaching the color out of it over time.
I wouldn't worry about UV doing extensive damage to nylon gear during normal climbing use, more about leaving nylon gear out for long periods of time (weeks) exposed to the sun.
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rtsteed
Sep 25, 2011, 6:43 PM
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That's what I have always thought, but recently I did some contract work for a camp and they leave their challenge course ropes outside all summer during camp. That is against industry standard and I had never been to a place that has done that in the past. I didn't say anything since I wanted to double check my facts before I brought the issue up.
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snoboy
Sep 25, 2011, 9:30 PM
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I don't have a reference for you, but I was just talking about this with a well known rope guru...
Mammut put ropes out on the roof of their head office, and also at 4000m in the Alps for a whole summer (maybe more???) The ropes that were at altitude pull tested at 95% or greater despite being bleached etc. The ropes on the office roof pull tested at a lower strength - attributed to air pollution.
Also ropes that spent two seasons fixed on Denali were also tested, and despite being bleached totally white, also tested at a high percentage of original strength.
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patto
Sep 26, 2011, 12:13 AM
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Switzerland isn't know for its high UV levels. Conduct the same test in Australia and you'd get 10 more UV damage.
Either way leaving Nylon exposed to UV does weaken it significantly. If you are replacing the ropes every year then it likely doesn't matter. If you aren't then there is more of a concern.
Also UV large only affects the sheath of kermantle ropes. But look what happened to forum user USNAVY recently on a UV exposed rope!
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blondgecko
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Sep 26, 2011, 1:16 AM
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Patto beat me to it. High energy UV will most certainly break chemical bonds, and hence degrade nylon over time. However, its penetration through most materials is measured in small fractions of a millimetre, so essentially none of it will get through the sheath of an intact kernmantle rope. Leave a rope with a core shot out for any length of time, though, and I don't think I'd want to witness the consequences of falling on it.
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blondgecko
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Sep 26, 2011, 1:19 AM
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Oh - just wanted to add. If you want to test this for yourself on a smaller, cheaper scale, leave one length of monofilament fishing line out in the sun for a few weeks, and an identical length in a cupboard. Then compare breaking strength on the two.
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rtsteed
Sep 26, 2011, 2:12 AM
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To be more specific, challenge courses also use hawserlaid rope for participants to traverse across the course. Here is the hawserlaid rope they were using (http://www.advexp.com/product.asp?ProductID=11284).It is a reduced-stretch, three-strand rope of polypropylene core, sheathed by polyester yarns.
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blondgecko
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Sep 26, 2011, 3:19 AM
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rtsteed wrote: To be more specific, challenge courses also use hawserlaid rope for participants to traverse across the course. Here is the hawserlaid rope they were using (http://www.advexp.com/product.asp?ProductID=11284).It is a reduced-stretch, three-strand rope of polypropylene core, sheathed by polyester yarns.
Ah. That's a bit different from your average climbing rope - in material as well as construction. Polyethylene terephthalate (the polyester that forms the sheath) is one of the most UV-resistant polymers out there - it's the most commonly used fibre for sailcloth, which obviously has to stand up to UV and take a beating. Polypropylene performs poorly under UV but is hidden away in the core, and has the advantage of being resistant to just about all chemical attack (seriously - most solvents, concentrated acids and bases these days come packaged in polypropylene bottles). Between the two of them, that's going to make one heck of a stable rope.
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rtsteed
Sep 26, 2011, 4:19 AM
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They leave their kernmantle rope out too. I am just not a fan of leaving rope and hardware out for months at a time.
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blondgecko
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Sep 26, 2011, 5:47 AM
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Well, it's not great, but the evidence suggests that it's not necessarily incredibly bad either. Depends on how often they change their ropes.
As another example, consider the ropes used on sailing yachts. They're typically kernmantle spectra (ultra high molecular weight polethylene, a close relative of polypropylene). They spend day after day, week after week in full sun, getting regularly doused in salt spray, and often experience extreme loads (you ain't seen shockloading until you've seen the boom on the mainsail of a 40-footer unexpectedly swap sides due to a change in the wind/poor steering). Even so, those things last for years.
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philbox
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Sep 27, 2011, 3:10 AM
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Anecdotally I jugged a rope left out for about 14 months, on a north facing wall which is in the sun all year being in the southern hemisphere. The rock is black so summer temps could bake an egg. The sheath had become core shot for about a metre. I backed myself up with being on a lead line and placing a piece every now and then. Scary but it held.
BG would know this mountain. Mt. Warning in northern NSW. The rope was quite bleached with hardly any colour left but some pattern. No way did I want to fall so hence the back up. Interesting feeling passing that core shot. Also interesting is that the jumar was fine and held my weight on the strands that weren't covered by sheath. Good old SRTE Explorer handled ascenders.
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blondgecko
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Sep 28, 2011, 3:18 AM
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Yes, I certainly know Mt Warning, and  .
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Kinobi
Sep 29, 2011, 3:53 PM
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Guys...
Holker, J.R., Vevers, B. and Warwicker J.O. - “Effetts of Ultraviolet Radiation and Sea Water on Polyester and Polyammide Yarns” - Trans. I.Mar.E (c) Vol. 97, conf. 2 Paper 26 and Reinert G., Photostability of Polyamide Fibres, Melliand Textilberichte 69 (1988)
And
Emanuele Pellizzari - “Anche le corde hanno un’anima” - Alp, n. 122-123 (giugno-luglio 1995), ed. Vivalda
There are many things to worry about,but very little so far for UV. Unless you are totally stupid to leave them for years under the sun
E
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