I am only familiar with what is used for rock climbimg.
I am not familiar with what BerkeleyPoint is selling; it must be a version for marine applications. I will have to drive by the BP store in Berkeley and check the stuff out.
Sometimes it looks like it melts but it is not melting with the sheath and the ends are not sealed.
.

Take a look at that document I linked. Spectra (R) by Allied Signal has a fairly low melting point. Technora (R) by Teijin has a quite high melting point.

Of course, you have to look at the specs for any given product to determine what materials they use.

-john

John,
So you have been able to fuse together the seperate strands of the Spectra cord sold by BP? Please tell us how you did it. It will melt with plain old fire for me, but the strands do not fuse together. BP recommends using whipping twine.

Yes, I melted the end of the Spectra cord from BP with a lighter. You are right, it tends to melt back and not fuse together as easily, but you should be able to get something good enough to keep it from unraveling.

As a side effect, you may get a bit of a 'ball' of melted stuff. If that isn't acceptable you'll probably have to try a different approach. Maybe wipe it against a hot object like a soldering iron or something.

-john

This is from a website;
http://info-central.org/recovery_cordinfo.shtml
Spectra Cord
Spectra cord comes in 2.0mm and 5.5mm diameters and is much like Kevlar in its properties. Spectra will not melt or stretch and is extremely strong for it's size and weight. It is so strong, climbing manufacturers routinely say it is 10 times stronger than steel. What makes this cord different is that the spectra fibers are on the inside with a nylon sheath woven over them to protect them from abrasion. Note: The spectra cord is relatively stiff and slick, because of this, only a triple fisherman's knot is recommended to tie it with.


This is from REI's website;
Cut about an inch longer than you need. Work a half inch of the core out of the sheath and cut it off. Smooth the sheath back and melt it into a smooth, hard "cap" on the end of the cord. This method of finishing will allow the cord to fit into the holes drilled in hexentrics. To get a clean cut on Spectra® cord, it may be necessary to use cable cutters.

The mfg web site claims 300F.

http://www.honeywell.com/sites/sm/afc/spectra_fiber.htm



This jives with what Tom Moyer's study states:

http://www.xmission.com/~tmoyer/testing/High_Strength_Cord.pdf



Compare to Kevlar (~932F) or Technora ~900F.

If I recall my Ray Bradbury, paper burns at 451F, so therefor it makes sense that it should be possible to melt Spectra with an open flame.

Also note that in the link you provided, they refer to Maxim as a Spectra product, but as we found, Maxim appears to be the name of a New England Rope Technora product, not a Spectra product.

-john

Well, part of why I was looking at tech cord for the hammock is becuase I haven't been called a lightweight in a while. :P I usually use a wrap of nylon webbing when camping, and then attach my cords to that, but if I can have my main lines also be how I anchor to the tree, that means that when I make a new hammock this winter, I'll have one that packs smaller.

As for shelter building, the idea I had was to make a something I can only call a "speedy cave" in winter, which is your basic tarp A-frame pitched in a spot you've dug down to ground in, then you pack the snow on top. I've tried them before, the cordage has a habit of breaking when there is a foot or so of snow on top of one of the heavy duty survival blankets (not the baked potato ones, the green on one side, silver on the other tarp ones). Never having had much luck with them in the past, I've not tried to build one in years, but after looking at Buffalo last week and them getting hit about a year after we got a nearly identical storm here, I've been giving it some more thought.

I'm just looking for somethign that is about as thick as paracord, maybe twice as heavy, and able to hold about 700 pounds reliably. And no, I'm not THAT big, wet snow is heavy. :P

No you are right; I just grabbed a piece of spectra off my climbing harness. After citting a piece I took out the spectra core and melted it with a lighter.
I think I associated the fact that the hot knife at the store could never make a cut; we always used a FRESH razor blade to make a clean cut. Then we melted the sheath by itself.
Turns out it does melt it just melts very differently than the sheath material which is regular perlon.

A lot of climbers refer to all varieties of specialty cord wrongly as spectra. But that website turned out to be wrong on more than one thing.

Ironraven,

I can picture your speedy cave, and can imagine the paracord breaking! :-)

I think a 3mm Technora cord would support the weight you suggest just fine. It's very small, light and very strong. You should try it out and let us know how it goes! ;-)

Billy,

Several good points. I've found a fresh razor as one of the few ways to get a nice clean cut on most of these high tech cords, esp. the Technora. That stuff is packed in there tight!

I'll have to try the melting-the-sheath technique you reference from the REI web site. I have really struggled with finding a good end for the Technora cord.

And lastly, yes, I think a lot of the high tech cords tend to blur together. For a long time I mistakenly thought the Kelty Triptease cord was Technora, when in fact is is Spectra.

Triptease is cool cord too BTW. Very thin and light but still quite strong. Very flexible (not tightly packed internally) and has reflective material woven in.

-john

Have you a favored source for 3mm Technora? Preferable one that is wallet friendly- mine is kinda bruised.