UV damage on nylon... Need source

[Ron 10]

I fly acro planes now and people are HORRIBLE about leaving their gear in the sun. I'd like to find a reference showing UV degradation on nylon, but my google foo is weak.

Can someone give me a good source?

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[GoneCodFishing 24]

Ron

I'd like to find a reference showing UV degradation on nylon,

Can someone give me a good source?

Have you tried googling "UV degradation on nylon"? Plenty of hits at differing levels of nerdyness...

[Ron 10]

Yep, and the level of nerdiness is a bit high. Looking for simple "X" days of exposure = "Y" reduction in strength.

I don't care about the chemical process involved.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[skytribe 17]

Just from reading a few of the hits from Google - you will realize that there are a whole load of variables and differences in Nylon materials which mean that getting a simple answer is probably not going to happen.

Thats said, the general opinion is the UV damages Nylon after exposure. That is not in doubt.

[Ron 10]

Yes, we "know" it.... But I am trying to show this to a group that thinks of the parachute as an expensive seat cushion.

If I had some source that said it will lose 10% of it's strength with "X" hours of exposure, then it would be a home run.

But just telling them "it happens" is not enough to bring a change of habit.

I'll keep looking...

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[betzilla 56]

for some reason I think @Peek might have some info on this, from an experiment he did. I could be wrong, of course, but maybe send him a PM?

[Ron 10]

Found this and it might work

http://nopr.niscair.res.in/bitstream/123456789/11890/1/IJFTR%2036(2)%20145-151.pdf

"It can be observed from Fig. 3 that the nylon
webbing (control) shows drastic strength loss on
exposure to outdoor weathering. The strength loss
after the initial exposure period (i.e. after the first
month) is 24%. "

So that is a start.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[GoneCodFishing 24]

Unfortunately the variables are too great for a simple x does z.

There was an study specific to parachute zp, where they exposed it to the sun in the desert and found that strength loss was significant after 24 hours exposure. I think they found that the color of the fabric was also a major variable on how it was affected.

I'll see if i can find it

[RockSkyGirl 10]

Search "high visibility" in the forums and you'll get a post with that specific spelling which is about canopy colors as the top hit. About halfway down the first page you'll see LloydDobbler's reply; he is referencing the 2007 PIA Symposium.

Quote

Yup. And it's not just fading you have to worry about. Soko (master rigger, head AFF-I at Cal City) gave a presentation on color & ZP fabric endurance at PIA this year. Instead of using artificial UV light sources, though, he exposed various ZP fabric colors to direct sunlight (giving full exposure to all wavelengths of the EM spectrum - not just UV, but also IR & visible light) over a period of time. He then tested them with regard to aesthetics (color fading) & tensile strength.

I won't belabor the results, but basically he found that the following colors lost the ability to withstand wind and/or 40lbs. of tension after 291 hrs of exposure to direct sun:

- Magenta
- Watermelon
- Neon Pink
- Tangerine

(If you consider that a sport canopy is exposed to sunlight 6-12 mins per jump, that equivalates to ~1450-2900 jumps in direct sunlight.)

Other colors (including bright colors like Lemon) showed aesthetic degradation, but maintained tensile strength at 700+ hours (3500-7000 jumps).


If anyone wants more info, PM me, and I'll forward along the powerpoint data I have.

As a climber, I learned long ago that climbing nylon (ropes, harnesses, webbing) exposed to sunlight loses strength very quickly if it's exposed to sunlight for long periods. If it's faded, we don't trust it. But from the study discussed in the 2007 post, fading doesn't necessarily equate to a loss of strength in parachutes; it's based on the color as well. Not that I'd want to pack or leave my canopy out in the sunlight, though! Take care of your gear if you want it to take care of you.

[mxk 1]

RockSkyGirl

Search "high visibility" in the forums and you'll get a post with that specific spelling which is about canopy colors as the top hit. About halfway down the first page you'll see LloydDobbler's reply; he is referencing the 2007 PIA Symposium.

Link: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3131726;#3131726

[SkySquatchy 0]

Heck, find an old canopy that has been retired from service, and cut out swatches of faded orange fabric. Also get swatches of new orange fabric. Give a swatch of each to the doubters and ask them to do a "thumb test" on both samples. Stand back and watch their expressions. First hand experience is far more convincing than a quote from some obscure study.

[gowlerk 2,216]

Why bother? It's not that they don't believe you. They don't care. Their restraint systems are life limited because of UV exposure as well. It's aviation and they accept the expense. Their riggers will ground them when they get too faded!

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[rmarshall234 14]

Here you go:


You might also want to share this story....

While working at Brown Field in San Diego if we couldn't find a lost cut-a-way within several days, it was written off due to the UV exposure by that time.

[Panthim 0]

There is a PPP by Ralf Homuth held on the INSITA 2013 (in German):
https://www.dfv.aero/downloads/6_-_TECHNIK_-_Fallschirme_in_der_Zerreissprobe.pdf
in the second part You can find some graphs / tables.

have a nice day
jörgen, Member of the "Beef"

[GLIDEANGLE 1]

See:

Poynter, D. (1991) The Parachute Manual Vol I. Santa Barbara, Ca; Para Publishing. pg: 499. section 9.3.1.8.15

Of note:

1. The cited page has a chart showing % change in breaking strength of nylon over time in sunlight (both direct sun, and sun through glass).

2. There is a comment at the bottom of that section about revealing UV damage to nylon by inspecting it for white fluorescence under UV light.

Your local parachute rigger is likely to have a copy of that book.

The choices we make have consequences, for us & for others!

[Ron 10]

This is exactly what I was looking for, thank you.

You too Jim. I have the manual, just could not find the correct reference.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[pchapman 279]

One has to be careful about what type of nylon any given source is talking about. Thin parachute nylon will be more affected than thicker cordura, which will be less affected than thick parachute webbing.

Although webbing will lose strength slower than canopy fabric, faded webbing can still lose a lot of strength.

I hope pilot emergency rig makers have gotten better at covering risers over the years, as the risers over the shoulders take a lot of UV beating from those pilots not covering their rigs in the cockpit.

The Wilcox webbing strength tests -- somewhere out on the web and at one time in Skydiving magazine -- focused on abrasion, bad needles, and cuts, but also had a page on UV damage. Some olive drab (or similar) Type 7 webbing went down to 84% of original actual strength in 80 days in the sun (I think in Florida), and was down to 43% in 360 days.

[pchapman 279]

To append to my post:

The UV damage section of the Wilcox tests was already in post #13 of this thread, by rmarshall, although with no attribution provided.