Nylon or polyester. How to tell the difference?

[actionoptics]

Just tidying the loft and found two lengths ( 43m and 96m ) of 12mm 3 strand. Is there an easy way to tell whether they are nylon or polyester? They have three coloured strands running through them - light green; light blue and mixed dark blue and red.

 

[johnalison]

Not always easy, but nylon feels silky and slightly oily to touch and has some stretchiness if you tease out a strand.

 

[VicS]

Warm a little in a dilute solution of a strong acid, eg hydrochloric acid (brick cleaner) or sulphuric acid (battery acid), and cautiously with a dilute solution of caustic soda.

The acid will attack nylon while the caustic will attack the polyester. (I think)

I have never tried it so I would want to try with a couple of known samples for comparision.

What would I have done when I was working?......give it to the analytical Chemists or if I had to do it myself a Lassaigne (sodium fusion) test for nitrogen which would be positive for Nylon

 

[duncan]

does it matter? They both do essentially the same thing and the very small differences in stretch and BS shouldn't be critical to sensible marine applications.
anchorplait is now made in both and not even labelled N or P in some retailers!

 

[bluedragon]

I've noticed that white polyamide (nylon) goes yellow in sunlight after a few days when new (then loses this colour for some reason?). Anybody else seen this? After a year or so it's got stiff enough through UV ageing that it probably stretches less than polyester!

 

[Simes]

Yes I have also noticed this. Just purchased a lot of 22mm nylon, it has gone a mid brown colour where exposed to UV. Colour dissapeared when moved to a shaded location. I presumed that this meant that it was not Nylon but Polyester, not that fussed as they do the same job at the strenth and at similar prices.
I do think that Polyester is easier to handle, but harder to splice (esp the Butane back-splice)

Rgs

Simes

 

[eyehavit]

Take a few sample strands from each rope.
One at a time apply a flame to a sample, for sufficient time to cause it to just burn unaided and immediately extinguish the flame by blowing or dry smothering. The fumes that emit can be useful in identifying what the plastic is.

Nylon has a smell not unlike burnt hair.

Polyester has an offensive acrid odour, nothing like burnt hair.

 

[Graham_Wright]

I think polyester floats and nylon doesn't.

 

[Black Sheep]

Nope - they both sink. It's polypropylene that floats.

 

[GMac]

Burn an end of it, rope cutter works best or a hot blade of some type. If the left over melted bit is black it's probably nylon. Polyester, while discoloured, melts noticeably clearer.

Another one is drop a bit into a pot of nearly boiling water. If it suddenly/ instantly goes very hard and stiff I'd pick nylon. It will soften up when cooled down unless you leave it there tooooooo longgggg.

Generally a Nylon has a green or red trace and Polyester a blue. Saying that your appears the be a manufacturer mark as well. Judging by your list I'm going with a Nylon.

Nylon that discolours like mentioned in posts above is usually a sign of a lower grade raw product. Maybe only a textured nylon (clothing industry) as opposed to the usual T6 or T6-6 use in the marine game. This is becoming more common as more is 'built to a price' rather than built for performance. Don't grizzle, they are only responding to demand.

Correct above poster person - polyprops the floater where the other 2 do sink.
And other poster above - Yeap, they pretty much do the same thing for most applications.

 

[actionoptics]

Thank you everyone. It's polyester.