953Re: Hammock Camping Digest Number 85
- Apr 3, 2003Hi, "Geoflyfisher,"
Thanks for the response. I have a couple of comments, inserted below.
From: "geoflyfisher" <geoflyfisher@...>
Subject: Re: Near Disaster! "Autopsy" Results
Great points in your post (pun intended ;) )
The hammock material which failed was uncoated ripstop nylon. I was
using a standard sewing machine needle... not ball point, not
cutting needle, just sharp... When I made the bar tack, I had just
sewn dozens of feet of hook and also loop velcro, which tends to
cause burrs on the needle occasionally.
I believe that ripstop nylon would be less likely to be weakened by
sewing than silnylon is. The silicone stablizes the fabric thread
and may allow it to be cut by a needle when regular woven cloth
threads would be allowed to be separated by the needle.
##### I believe most of the silnylon that I've seen is also ripstop, but it was a finer denier (thinner) than most polyester or nylon ripstops that I've seen. I've only done a very little sewing with silnylon, so far. I really don't know whether to expect the fibers to be pushed aside by either a ball point or woven point needle, if it matters at all, or if we really need the finest, cleanest possible holes, or the optimum spacing to further reduce further weakening, and hope the silicone will stabilize the fabric to stop fraying or other problems. I would rather not find out the hard way!
For this reason, silnylon and tyvek may have some inherent weakness
for the weight supporting part of hammock making which the woven
ripstop does not.
####### I suspect the main concerns here would be the thickness, leading to the strength of the materials, and whether or not they have weak spots from stitching lines. If the fabric behaves as if it were perforated, as opposed to sewn , I infer a big problem. I don't know if Tyvek is spun or woven. It seems almost pressed, like paper. We all have seen perforated paper, and what the perforations are for. I think most fabrics fit either "woven" or "knitted." So, I think you are trying to distinguish between silnylon and non-silnylon fabrics. Sport cloth seems to refer to a range of (mostly) nylon fabrics, of varying deniers, coatings or non coatings, etc., in my local fabric shops. Unfortunately, no one around here seems to carry silnylon, or other materials desirable to the lightweight crowd. Silnylon comes in different deniers, too. I'm pretty sure the body and fly of my Hennessy Asym Ultralight is silnylon. I will have to look closely to see if it is ripstop.
I pointed out what I did to allow others to avoid over sewing the
velcro at such a vulnerable location. As Ed Speer noted, it is
likely the many needle punctures of the material which caused
weakness instead of strength.
I picked that up before, and think it is a good point to keep in mind. Maybe save bartacks for flexible, stretchable materials like denim for jeans?
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