Guideline suggestions - 24 gauge nylon line dissolving

[caveandreas]

Hi guys,

I looking for suggestions for guideline to use in a highly corrosive cave.

Some months ago I found myself replaced some kilometers of #24 line that was originally installed in 2004 and 2015. After 20-9 years it was not even possible to reel the line in, it broke with any tension on the line, and was really hard to reel back in as it constantly needed repairs to get onto the reel. I usually use #18 on my exploration reels but in this particular cave that would probably not last very long, but it is what it is replaced with right now.

I'm not entirely sure about the chemical profile of the water in this cave, but since all the brass turns black and it smells like rotten eggs I'm pretty sure a big part of the corrosive nature of this cave is due to the (VERY) high amount of hydrogen sulfide. But there might be other natural chemicals at play as well, as no other place with just H2S is this bad in my experience. Nylon and H2S should not be very reactive but it does interact according to charts i found online. But I'm not sure what other material would work any better than the current nylon line.

If any one have experiences installing line in caves with moderate flow that is also highly corrosive I would love to hear your experiences of what line you ended up using.

 

[CoachWade]

I’m a trained chemist and kinda recall a little about nylon from my college days;

Last time i messed with sympathizing nylon in a lab situation, I was a GTA 20+ years ago… nylon is synthesized in an aqueous environment and is formed by a condensation reaction which releases water. Perhaps le chatelier's principle can be at play if the nylon is left in water then water might reverse some of the synthesis (?) but that’s a wild guess as this is not in what was my area of chemistry.

One fact I do recall is that nylon can be broken down by a strong acid in a acid hydrolysis reaction AND it can also be broken down by a strong base in an alkaline hydrolysis reaction but I doubt you are dealing with a strong acid or a strong base.

In chemistry in general we refer to water as the “universal solvent” water will break down everything eventually…

 

[tbone1004]

not a trained chemist, but a textile engineer. Won't go into all of the reasons why nylon is a bad choice for a lot of line, but it's used because of its tensile strength and abrasion resistance and we tend to ignore its downsides.
If you can find polypropylene or polyethylene line it will have much better acid resistance than the nylon. Even polyester will be much better than nylon, though not as good as the PP or PE

 

[DogDiver]

You might try 300 pound Dacron fishing line. I used it on my reels for Great Lakes wreck diving.

 

[crofrog]

not a trained chemist, but a textile engineer. Won't go into all of the reasons why nylon is a bad choice for a lot of line, but it's used because of its tensile strength and abrasion resistance and we tend to ignore its downsides.
If you can find polypropylene or polyethylene line it will have much better acid resistance than the nylon. Even polyester will be much better than nylon, though not as good as the PP or PE

Divesoft Polyethersulfone (PES) Line

A {656 ft | 200 m} spool of 1.6mm PES (polyethersulfone) cordage developed specifically for cave diving. The prominent characteristic of the PES material is the exceptional tenacity; in water it is over five times stronger than polyester with very good abrasion resistance.

www.divegearexpress.com

Would something like this have better resistance?

 

[tbone1004]

Divesoft Polyethersulfone (PES) Line

A {656 ft | 200 m} spool of 1.6mm PES (polyethersulfone) cordage developed specifically for cave diving. The prominent characteristic of the PES material is the exceptional tenacity; in water it is over five times stronger than polyester with very good abrasion resistance.

www.divegearexpress.com

Would something like this have better resistance?

Much better than nylon yes, it does have some weird chemical resistance issues with certain chemicals so a water sample to figure out what exactly is in there would be helpful. Keep in mind that that stuff is very thin, #24 normal cave line is close to 2mm in diameter and this stuff is only 1.2 so depending on what you're tying it around it may cause gouging issues or even cut some of the softer limestone if you have too much tension on it since the pressure point is significantly higher. I hate working with super thin line, especially with gloves on

 

[macado]

I feel your pain. I had to replace thousands of feet of line in a particular cave in Cozumel. Even just gently touching it or tying off would make it snap or completely disintegrate. It would not be fun in a no-viz scenario.

I'm definitely interested in alternatives, in an effort for some sections to last longer I replaced parts of it with #36 (purely because I already had a lot of it) but it's eventually going to have the same disintegrate issues. I may replace it with the polyethersulfone line from above.

This is a section of the line I removed / replaced.

 

[macado]

Re-upping this thread. @caveandreas have you found a better solution?

I just replaced thousands of feet of #24 braided nylon that was only installed 2-3 years ago. It is completely rotted and snaps easily.

I think I am going to experiment with polyester (dacron).