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  1. #51
    WV's Avatar
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    Quote Originally Posted by catalyst81 View Post
    I'd be interested in the results of that. Right now I keep wavering between the lighter and heavier cuben currently being used by most the cottage companies making winter hammock tarps. Seems like the difference in weight is 6.5 oz to 10 oz for the tarp depending on the material used.
    Right. Your choice of tieouts and stakes (how many, materials) may make more of a difference in the overall weight.

  2. #52
    Senior Member animalcontrol's Avatar
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    Quote Originally Posted by WV View Post
    I'm tempted to do some comparative puncture testing by stretching some pieces of cuben, Spinn and Silnylon on my wife's quilting frame and dropping sharp objects (screwdrivers, pine cones, etc.) on them from different heights.
    Those pesky screwdrivers fall on me all the time!!!

    it would be a great test tho!
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  3. #53
    Senior Member finskie's Avatar
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    Quote Originally Posted by fin View Post
    Most people do not sew the ridgeline on Cuben (One of the tarp makers does on their tarps, hence the need to seam seal,) because in stress tests on cuben, it usually ends up failing at the sew lines. If the seam is sewn and taped, cuben normally fails at the edge of the taped seam, not at the seam. Same goes with glued/sewn.
    Either way in this description, the tarp fails. Whether it is at the sew line, or at the edge of the taped seam. What I am wondering is: Does one of these ways fail under less pressure than the other, or is it just different ways of failing? Was your reason for sewing and then taping just to elliminate the need to seam seal, or to add strength? Just wondering for future purchases.
    What saves a man is to take a step. Then another step. - C.S. Lewis

  4. #54
    Senior Member fin's Avatar
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    Quote Originally Posted by finskie View Post
    Either way in this description, the tarp fails. Whether it is at the sew line, or at the edge of the taped seam. What I am wondering is: Does one of these ways fail under less pressure than the other, or is it just different ways of failing? Was your reason for sewing and then taping just to elliminate the need to seam seal, or to add strength? Just wondering for future purchases.
    The amount of stress needed to make a sewn edge fail is less than a taped/sewn, glued/sewn, glued or taped edge. When testing, a sewn edge ALWAYS ripped in the same spot - at the sewn edge. Glue and tape has its own disadvantages, but the sheer strength of glue or tape is considerably stronger than a sewn edge. I taped to add strength. My tarp was version 1.5. The first tarp (1.0) was used as a test subject to test all the different methods of attaching tie-outs, with each tie-out using a different glue/tape/sewn combination. I will say that none of the methods used has failed on version 1.0, and that tarp's tie-outs and ridgeline are bomb-proof. The stress on a tarp is mostly on those points. Version 1.5 was done with sewing and tape on the ridgeline only, all the other attachments were glue/tape, except for the grosgrain tie-outs, which were sewn through several layers of cuben, then adhered to the main tarp. The ridgeline was sewn and taped to strengthen the bond and to seam seal. It was only done because I was on a very tight schedule to get on the trail, and I had concerns on the adhesion peel strength of glue and/or tape, which after more thought isn't really a factor on a ridgeline. If I could do it again, I would only glue or tape the ridgeline because it would save time and not introduce weaknesses in the fabric that would need to be re-bonded through the use of tape.

    There was a lot of research and reading done on the subject of bonding cuben, sheer strength and peel strength before a cuben tarp was attempted - it costs too much to fail just for fun. When you glue or tape cuben, you are basically bonding the polyester film surface that is used to encapsulate the dyneema strands. There is no way to make a seam that is stronger than the material itself because of this. Cuben will tear, and if you induce a hole in the fabric by sewing, it creates a flaw in the fabric that can be exploited by stress. You are definitely creating a weakness in the film surface and possibly damaging the dyneema strands, although that is unlikely. But you are creating a place for the film to start its tear. The amount of strength needed to start that process is more stress than anyone will probably ever put on their tarp, but it is still the weakest point, and the weakest way to join two pieces of cuben based on people a lot smarter than me with a lot of fancy equipment and big words to throw around.

    On the question of whether a cuben tarp needs to have finished edges: Not really, it is done to make it clean and pretty. Cuben doesn't fray like silnylon. I seriously debated whether or not to do it, but it just makes it cleaner. The edges of my tarp were sewn - just because the amount of force along the edge of the tarp will never reach the failure point of that method. Tie-outs and ridgelines, I have probably put them to greater stress than I ever put a silnylon tarp to. I saw Brian's (OES) prototype cuben tarp at Trail Day's, and he also stayed away from sewing. BTW, he is a great guy in person, glad to have finally met him. Hyperlight Mountain Gear, Mountain Laurel Designs, HammockGear with Adam's new tarps - all use tapes and/or glues to bond their cuben tarps with little or no sewing, and if they sew, only where it is cosmetic and not critical. That alone says something, doesn't it?

    Have fun, guys! I have to get my new hammock done so I can get back on the trail!

  5. #55
    Senior Member finskie's Avatar
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    from one fin to another, thanks
    What saves a man is to take a step. Then another step. - C.S. Lewis

  6. #56
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    I don't know how many people here are also on the Backpackinglight.com site, but there are a couple of obsessive fabric scientist types over there that have been testing cuben fiber along with other materials. I look at cuben fiber stuff, but I could never justify the expense so its just idle curiousity for me (still, looking at nice gear is one of life's simple pleasures).

    It looks like there are a couple of issues that the mad (fabric) scientists at bpl have found:

    1. The QA on cuben fiber is all over the map. Some of the lighter stuff seems to be really water proof, but then another batch will be worse than better grades of .9 oz dwr nylon (see this chart - the higher the number the more water pressure it can resist). Looks like silnylon has awful QA as well, so this isn't a criticism of cuben.
    2. They simulated wear and aging by putting the material through the washing machine. Even cuben that starts off super waterproof breaks down pretty rapidly (like lightweight silnylon). Seems that stuffing and unstuffing it would really start to wear down the waterproofness. Here is a chart that is almost totally incomprehensible until you've spent some time reading that huge thread:

      The only stuff that made it through 4 runs of the washing machine without losing waterproofness was 3mm plastizote sheet, eVent, some 1.0 PU ripstop from oware, a 1.5 oz PU coated ripstop and some mylar stuff (maybe a heetsheet?). Most cuben seems to lose a bunch of its waterproofness and then levels off. The cuben fiber thats over 1 oz/sq yd typically levels off above the official "waterproof" rating, the rest seem to come below the line. Officially "waterproof" is over 1500 mm of water pressure - some of the lightweight cuben doesn't degrade, but wasn't really waterproof to begin with.
    3. The best value for a high quality waterproof material seems to be "shield" 1.1oz silnylon based on the mad fabric scientist's testing protocols.


    I didn't do these tests, and I'm not arguing for or against them, just thought folks might be interested in what these tests say about Cuben, especially compared to silnylon, PU coated nylon, and even CCF and mylar! Can you imagine a CCF tarp? Hmmm...

  7. #57
    Senior Member DiscoveryDiver's Avatar
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    Thanks for posting that...very interesting!

  8. #58
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    Quote Originally Posted by pizza View Post
    Great write up fin! It was very informative.
    +1 on the great write up

    I have one of Hammockgear's new Cuben tarps and after Fin's instructions have cranked up the tension on it.

    It pitches perfectly. And weighs only 6.6 ozs, less lines. It has become my tarp of choice.

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  9. #59
    Senior Member finskie's Avatar
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    Just because i was curious, I emailed a sail maker by the name of Bill Shore (shore sails). I asked him what was the prefered method of attaching 2 pieces of cuben. I figure that a sail is put under considerably more force than a tarp. So his response was that all three methods had been used (sewing, glueing and taping). What was interesting is he said that sewing was added to glueing for "hotter climates". Now a sail at sea is getting the full brunt of the sun all day. I'm sure that a tarp does not suffer the same amount of prolonged heat. Still, it makes me wonder about temperature changes over time affecting the chemistry of the "bonding" or "taping" method. Only time will tell, but I'm thinking it may be a non-issue where tarps are involved.
    What saves a man is to take a step. Then another step. - C.S. Lewis

  10. #60
    WV's Avatar
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    Quote Originally Posted by finskie View Post
    Just because i was curious, I emailed a sail maker by the name of Bill Shore (shore sails). I asked him what was the prefered method of attaching 2 pieces of cuben. I figure that a sail is put under considerably more force than a tarp. So his response was that all three methods had been used (sewing, glueing and taping). What was interesting is he said that sewing was added to glueing for "hotter climates". Now a sail at sea is getting the full brunt of the sun all day. I'm sure that a tarp does not suffer the same amount of prolonged heat. Still, it makes me wonder about temperature changes over time affecting the chemistry of the "bonding" or "taping" method. Only time will tell, but I'm thinking it may be a non-issue where tarps are involved.
    I checked out the technical bulletins that 3M issues for their various adhesives, such as this one for 9460PC adhesive transfer tape. If I'm reading it correctly, the level of heat a tarp would be subjected to is not a problem.

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