Author Topic: Identification of cord material  (Read 7133 times)


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Re: Identification of cord material
« Reply #15 on: November 21, 2006, 07:41:43 AM »
I'm never really sure with Dan's replies whether or not he knows something but isn't telling
or whether he knows nowt and is still telling nothing?  Cmon Dan "the book has maybe nothing
expressly about making the determination..." and then you waffle on ...
 What do you mean "has maybe nothing..." - does that mean you have read it and found
it to be lacking or does it mean you haven't read it and are just making this up [has maybe nothing]
based on what you have read in an entirely different document?  ...
 BTW - the book I referenced had a ton of information, but none of it was something that was
either quick or dirty or even a combination of the two!
Goodness, Lindsey, you have quite a way of unreading!   :-[

Perhaps you should reflect even half a moment on what was stated here before leaping
into a rant.  Derek's looking for means to determine fibre type, and had found my words
and similar ones (similar source, so not surprising).  You come along and make a grand
assertion that the Handbook... "has an absolute ton of information about determining
the type of cord ... chapters 1,2,4,9, & 10 at least".  How about anwering your own questions
to me of yourself:  i.e., what is YOUR familiarity with this book?!  I am familiar with the book,
and hence my surprise and my response.
I'm also familiar with long, short, & metric tons; maybe an "absolute" ton is much lighter?

Having got that off my chest I am now searching for some illumination about how to help others determine the type of cord.
Since you introduced the book (and have sold Roy though he claims to have read
my msg.s, sometimes), maybe you can bring some illumination on it to the thread?
I'll give you Chapter 9 for free, for starters:  it makes only the briefest mention (even)
regarding fibre type, and otherwise lays out a regimen and items to consider when
inspecting used rope, of which only one is specific to fibre (PP splinters from UV).

I do not think that burn tests will definitively tell us which kind of line it is or is not,
unless you just happen to have a thermometer that reads to within +/-25 degrees and up
 to 450 degrees and can be used with melting plastics - everyone has one of those, right?
What part of the aspects of smoke color, flame support, rate of burn, odor, and nature of
residue don't you believe?  Actually, the previously referenced use of burn tests is maybe
the one thing that IS in the Handbook... and of use (and is--here's another freebie--
the sole part of Chapter 10 (Tables 10.3 & 10.4) that is relevant, which is otherwise concerned
with the definitions and instrumentation involved in testing--the sort involving expensive
machines and sometimes thousands of cycles of specific loading (and not for finding fibre type)).
As for definitive determination, well, what's at stake here?  --good enough in many cases,
for the beachcomber.

(how do we tell if it black smoke from the piece or from dirt entrained in the piece?)
Take a few samples and use cleaner, smaller bits.
But what if one suspects the vendor of adulterating nylon or polyester with polypropylene?
(Recall that burn specimen I had that seemed to burn inappropriately.)
Yeah, there might be some shrugs of uncertainty, doubt.  But the simple burn test
is likely adequate for much of what many will need to know.
(The simple float test can have surprises when encountering PP lead line
--I opened strands and had dirt come out and eventually realized that
it wasn't quite that, but was bits of lead (amply flexible 1/4" 3-strand rope,
which sank!).)



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Re: Identification of cord material
« Reply #16 on: November 21, 2006, 08:42:45 AM »
Hi Dan,

Yes you can, yes you have and yes you do - make fun.  Seriously - you have read the book?  Then I perhaps should not point out the difference between fibre and cord?  Derek asked about cord and you talked about fibre, even talking about the mixtures of fibres - the book to which I was referring had a ton (DO pardon the colloquialism!) of information - meaning I considered it had a lot, more than a little, probably thirty or so pages, of information about cord identification - in the lab - including valuable insights to be gained by the prescription of what testing apparatus to use, with proper rejoinders about how to use it safely.  Cord is composed of fibres as you point out - a mixture of fibres.  So if Derek was looking to identify cords, how is it helpful to identify fibres, except that, if the cord is pure fibre and not adulterated by dirt, flammable materials, degraded by acids or oils, manufacturing chemicals, or anything else, then we do agree that perhaps - and I say that somewhat tentatively - perhaps we have some means of testing using simple means to get an accurate statement about what a cord is and is not - things like density testing (in the book), burn tests (in the book) stretching (in the book) abrasion resistance (in the book) resistance to oils and greases (in the book) should I go on?

In Chapter 9, are you saying it is not useful to know when to retire a piece of line?  Is it not useful during inspection of a piece to know when it has reached its limit and know how that compares with another piece of cord?  Is it not useful to know what may be expected of the aging of a piece of line?  I do not have a unilogical mind - I am opening up my inquiring mind to examining all facets of the piece, including test methods, retirement practices, comparisons during aging, so that I get a complete picture in attempting identification - history, exposure, treatment during lifetime, treatment prior to sale, etc.  Do you not want that?  You have said you will give me Chapter 9 for free - what that means I have no idea.  You again make reference to fibres and not to cords - is it fibres we are looking to identify, in their pure form, or cords in their adulterated form?

You have taken me to task without others' benefit of knowledge of the book - the others who read these posts are not blessed as you or I with possession of the book in question, so maybe we should continue the discussion in a less public forum.  You have taken me to task because you say that I have not read your comments - I read them VERY carefully!  The burn tests are but ONE of the tests prescribed, and they state that they are not sufficiently definitive, that other tests are required.  While I greatly admire your ability to make determinations of a scale that others can only dream, just because you say so does not make it so.  I will contend to my last breath that burn tests are not even remotely a sensible way to definitively test a piece of line, even for as you say, a beachcomber.  If I am going to identify a piece of cord I want to do a complete job - if you just want to make a statement and have others believe it, so be it.

I am more interested in why we need to know - if it is idle interest, so as to give it a name, then call it cord or line, plastic or natural - that should be good enough as you say.  If I have a section of line in my storage area which I do not really know, and I want to use it for some mission critical purpose, then I suggest as I did before that manufacturer testing in a test lab is the way to go.  Then there is that murky area where I want to be able to impress someone by saying (here I can only guess at what may be said) "that is definitely a piece of polyamide, with tracers of polyethylene, probably put there to stop trade theft" or whatever.  That is an area I do not think we should encourage - let's leave testing to the professionals and by all means why don't you continue guessing what a cord may be on the basis of testing using a butane lighter or a match, without even the benefit of solid information - I just will not do it. ;D



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Re: Identification of cord material
« Reply #17 on: November 22, 2006, 06:32:40 AM »
So if Derek was looking to identify cords, how is it helpful to identify fibres,
It is principally what he is seeking to know.  And typically it's not as complicated as
you want to make it, though, yes, it might in the simple tests one can do not come
to the highest level of certainty.  E.g., there's not much indication that in the burn
tests additives/finishes will affect all of the results.

things like density testing (in the book), burn tests (in the book) stretching (in the book)
abrasion resistance (in the book) resistance to oils and greases (in the book) should I go on?
Maybe a float test can help separate floaters from non, in cases of multifilament
cordage; then a burn can further the discrimination.  Resistance to chemicals, UV,
& abrasion isn't the sort of thing one can easily check (and I think that all of the'
synthetics resist oil/grease; some vendors however have concerns about the
additives to gasoline).  But it would take quite some time and some leap of faith
to make much of the book's information about these aspects into a test method
for determining rope type (and we can note that the book in its limited discussion
of such determination doesn't cite these).

In Chapter 9, are you saying it is not useful to know when to retire a piece of line?
What I said was the this chapter had no relevance to determining rope type.  period
Rather, it more presumes one knows this, though again it doesn't distinguish on
fibre type (i.e., chem. compoosition) any of its checks, except for the ONE point
about PP ropes and monofilament fibre splintering (which, yes, one could reverse
and presume "if  ... splinters, then => PP").
(But it was in your ton of information, at least.)

But, to Derek, you should find the book worthwhile, and might swallow its
steep price; one can pay a lot less for a lot more and still have a LOT less
(many times over). Just mentally allocate the price over the many other
things that will come along for cheap in your mass of literature growth,

I am more interested in why we need to know ...
It's a natural curiosity, and we might care to see how certain ropes behave,
or figure what was used by someone for an apparent task (as best one
can then assess from the flotsam-jetsam remnant).  And maybe such
knowledge plays a role in employing some find in later use (sometimes
a great deal of cordage can come ashore).  One won't be using cordage
of unkown origin (and history) in any mission-critical application, but for
something less demanding, it's possible.

Probably some people will be in areas where certain ropes are common,
and so might have some usual ambiguities to resolve--nylon vs. polyester;
PP vs. PE vs. coextruded PP/PE and maybe that cited Karat brand of
coex PP/PES (I'm unaware of another such rope); or in yachting of some
of the hi-mod stuff.  Burn/no-burn quickly sets apart HMPE from Vectran
& aramids (maybe scarcity rules out PBO).

Some other aspects which might be nice to know will remain a matter of
guesswork (more so, if you insist)--such as whether the PP rope one
found is well made with stabilization vs. UV (in case you want to use it
to support that sapling or other sunny task (once found one of those
3-strand yellow-yellow-black PP ropes with the yellow strands bleached
clear & disintegrated; the lone black strand held)).  I suspect commercial
fishers get to know a vendor for this sort of quality and the word goes
around (lots of PP & coex & polycombo cordage with them).

On a related note, it's interesting to go around and collect all of the information
(often presented in tabular form) about fibre characteristics (and for that
matter, rope-structure characteristics, too) and look at it all at once.  E.g.,
I've read that UV has NO affect on HMPE, and elsewhere that HMPE's
resistance is merely "good" or maybe it was "fair" !?  --or (and this was
in Samson literature) that it was "good" (or better), but then needed a
booster application of their proprietary UV-resistance treatment after
3 years (!).  I've seen mixed versions of which of PA & PES has the
better of, I think, both UV & abrasion resistance!?  --most curious!
(We should all beware the trampling of truth at the hands of marketers.)

Actually, this is a good exercise (and I'm abashed to say I've more
noted-in-passing than rigorously checked/compared such information).

« Last Edit: November 22, 2006, 06:04:45 PM by Dan_Lehman »


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Re: Identification of cord material
« Reply #18 on: November 22, 2006, 07:47:44 AM »
Thank you Dan,

Your reply was much better than mine and I am ashamed that I fall prey to arguments that are not, in my mind, definitive.  Thank you for your patience and for letting me know that I can be a better person - I am an old dog and I can still be taught some very valuable lessons - they don't come cheap and they don't taste good but they are nevertheless valuable.  A tip o' the hat to you, sir!



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Re: Identification of cord material
« Reply #19 on: November 22, 2006, 06:33:06 PM »
Starting really easy.  Could we have ideas on how to start to build up a Reference Swatch of known pure fibres.

What common fibre types should we start with and what are the best sources to get them from.
What cord types are good examples and sources for our reference set.

Is there a cordage supplier for example who already puts together sample swatches which could start us off.

I'm thinking Reference folder - how about an A4 ring binder or box file starting with three basic sections
- Animal
- Vegetable
- Mineral. 

Then use an A4 cards for every sample we acquire.

Pin/staple the sample to the card and add all the details you have about it - source - name - made from - results from any tests you have run on it - notes, particularly any notes on contradictions where it did not perform/test exactly as expected.  If you already keep such a library, how do you organise it?

The goal is - following Roy's example - start to build a reference library of samples which can be used in our comparative tests.

Could I suggest a standard though for posting replies.  Give information and advice from your knowledge, however great that may be, but aim it at the person who has little or no experience, who is coming into this field afresh and not only wants to learn how to tie and use knots but also has an interest in being able to identify the nature and traits of the various cords available to them.

Sometimes you guys forget that you have mega knowledge and experience in relation to the rest of us and what is obvious and of little further interest to yourselves is actually new and interesting to a lot of others - myself very much included.

So - ideas please on How To Build  a Reference Swatch Library of Cords and Fibres.