nylon or polyester rope?

[isandell]

I know this has been discussed here before, but over the years I have acquired several useful lengths of rope and want to know if they are nylon or polyester. I dont fancy setting light to them (and my sense of smell is not that great) or chucking strong acid or alaki about.

I made up a strong brine solution, 20 parts by weight of salt to 80 parts of water, added a drop of washing up liquid and dropped in small lengths on known material. After a few minutes, when any trapped air had bubbled out (the washing up liquid helps this), the polyester sank like a stone, and the nylon floated just on the surface so I am now able to test all the rope. (I guess a 25% brine solution might give a more positve "float or sink" test.)

Ian

 

[rob2]

I wish I could be certain about the relative bupoyancy of all the rope materials (too lazy on hols to do the Google search), but in general Nylon is considered a sinking rope, whereas polypropylene floats. Polyprop does have some uses on a boat, but is prone to chafe and is destroyed by UV so longevity is always an issue.

As both nylon and polyprop can feel "plasticky", are you sure it's nylon you've got?

Rob.

 

[rob2]

Actually, a quick search for density of the base materials yielded:
Polypropylene 0.92
Seawater 1.026
Nylon 1.14
Polyester 1.38

Rob.

 

[isandell]

Actually, a quick search for density of the base materials yielded:
Polypropylene 0.92
Seawater 1.026
Nylon 1.14
Polyester 1.38

Rob.

I got same for nylon and polyester from Marlow website.

I used Wiki for get density of 20% brine as 1.1478.

So the figures do all fit.

I now have a plastic bootle with about 250ml of 20% brine, ready for next time I want to test fpr nylon or polyester rope.

Ian

 

[macd]

I wish I could be certain about the relative bupoyancy of all the rope materials (too lazy on hols to do the Google search), but in general Nylon is considered a sinking rope, whereas polypropylene floats. Polyprop does have some uses on a boat, but is prone to chafe and is destroyed by UV so longevity is always an issue.

Rob: the OP's on about nylon and polyester, not polyprop.

 

[VicS]

I know this has been discussed here before, but over the years I have acquired several useful lengths of rope and want to know if they are nylon or polyester. I dont fancy setting light to them (and my sense of smell is not that great) or chucking strong acid or alaki about.

I made up a strong brine solution, 20 parts by weight of salt to 80 parts of water, added a drop of washing up liquid and dropped in small lengths on known material. After a few minutes, when any trapped air had bubbled out (the washing up liquid helps this), the polyester sank like a stone, and the nylon floated just on the surface so I am now able to test all the rope. (I guess a 25% brine solution might give a more positve "float or sink" test.)

Ian

t
Thanks for that.

I suppose more practical, but not as much fun as a Lassaigne sodium fusion test

 

[thinwater]

All you actually needed was a few drops of battery acid on a few frayed threads. Easy.

Alternatively, simply tying it to something and pulling would be obvious (the difference in stretch is considerable).

 

[rob2]

Rob: the OP's on about nylon and polyester, not polyprop.

I appreciate that, which is why I looked up data for all three. I was simply concerned that such a test may not differentiate between nylon and polyprop, which are suited to very different tasks.

Rob.

 

[GrahamM376]

I appreciate that, which is why I looked up data for all three. I was simply concerned that such a test may not differentiate between nylon and polyprop, which are suited to very different tasks.

Rob.

As you mentioned polyprop in your original post, in contrast to your comments we've found it by far outlasts nylon for chafe and UV resistance when used for mooring strops.

 

[Graham_Wright]

Set fire to a strand. The smell from nylon will send you reeling. (No idea what polyprop does though!)

 

[VicS]

Set fire to a strand. The smell from nylon will send you reeling. (No idea what polyprop does though!)

I would think polyprop and polyester will burn burn smokily but without noxious fumes . Nylon produces noxious ( toxic ??) fumes because it is a polyamide.

But the OP said he did not want to identify them by setting light to them.

 

[rob2]

As you mentioned polyprop in your original post, in contrast to your comments we've found it by far outlasts nylon for chafe and UV resistance when used for mooring strops.

Yes, whilst nylon is often suggested as the ideal mooring line, principally for its stretch to absorb snatch loads, not all nylon or polyprop ropes are equal. A loosely laid three strand nylon rope will have maximum stretch, but seems to chafe badly. Another downside is that nylon hardens after submersion - I guess this is all to do with its absorption of water? There are two ways of making polyprop ropes, the cheapest uses strips of flat sheet whilst the more durable is made from true filaments and is a different animal altogether, much stronger and chafe resistant. The latter type is difficult to tell from nylon apart from the stretch in a new rope. I had a professionally serviced mooring at one time which had polyprop lines which were hard as iron. Having said that, the whole game of making moorings last involves using the heaviest lines you can and parcelling them to avoid chafe!

Rob.

Bad day - can't remember any of the correct nomenclature, it's an age thing.

 

[Graham_Wright]

But the OP said he did not want to identify them by setting light to them.

It only takes a tiny strand - you wouldn't survive any more!

Sniff in and sniff straight again is the way.

 

[Mistroma]

t
Thanks for that.

I suppose more practical, but not as much fun as a Lassaigne sodium fusion test

That takes me back almost 50 years. I remember walking into the lab. to do a Sodium fusion and chatting briefly to a fairly new guy already starting one. A friend tried to catch my attention so I ducked back slightly to see what he wanted. There was a pop at that point and a min-flare shot just past my head. My friend simply pointed at the ceiling and when I looked up the fibre tiling was peppered in brown and black mini craters. I took the hint and set up my kit at a Bunsen on the bench behind. Apparently this guy hadn't done any before as was having a few problems.

 

[Graham_Wright]

It only takes a tiny strand - you wouldn't survive any more!

Sniff in and sniff straight again is the way.

Sniff in and sniff straight out again is the way. (I should have said - and missed the edit window).