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Geeking :: Sailcloth bags

by , May 23, 2012

Geeking :: Sailcloth bags

OK, straight up, we’re actually talking about Ultra-high-molecular-weight polyethylene, but that didn’t fit in the header space. What is UHMWPE? It’s a space age material from the space age (you know, the 70s, when they had space travel and Concordes and all the fancy stuff).

UHMWPE more typically moonlights under names like Dyneema, Spectra, GUR, Cuben Fiber and all sorts of proprietary names. It gets woven, laminated, diluted, extruded and messed with for a range of products; from ballistic protection, sails and bags, to snowboard bases, surgical implants and chemical-resistant containers.

It’s super strong, super light, puncture and tear-resistant, abrasion-resistant, chemical-resistant and slippery like Teflon. So why isn’t it everywhere? Those long molecular chains are pretty expensive to manufacture, so the stuff ain’t cheap. But when it comes to carry, it works a treat for high-end ultralight gear, which is what we mostly wanted to talk about.

Why carry UHMWPE?

You can build a fully waterproof, tear-resistant, abrasion-resistant rucksack that weighs about what your plastic shopping bag does. If you’re going on an adventure where weight is a factor, you can treat it like crap and it won’t let you down (or weigh you down).

Why wouldn’t you carry UHMWPE?

Well, apart from the cost, it can be pretty stiff and crinkly, pretty hard to cut and put together (reducing the number of bag makers able to work with it), and you can’t get it in heritage herringbone.

So why are we starting to see it more?

Because weight matters. But also, mills are starting to weave and laminate it with other fabrics which makes the stuff more approachable to consumers, reducing the plastic look to it and opening it up to more mainstream applications.

Rather than keep talking in generalities, we thought it would be good to get John Canfield’s thoughts on the stuff. He’s one of our contributors, as well as being a bag maker (check out High Above) who has been working with the stuff a fair bit lately. Here’s what he has to say…

A few things right out of the gates…

Sewing it: The stuff is expensive. What I use is over 5 times the cost of 1000D Cordura. This is a key reason why it is uncommon for large-scale production.

Stitching it: The stuff is difficult to cut with scissors unless they are really sharp. The material resists being marked with pen or pencil, but thankfully takes permanent marker for patterning. It has zero stretch. None. So everything you do has to be spot-on, and when using the bags you can’t just keep cramming, as the stuff won’t give.

Specifying it: The larger of the small companies like CiloGear have special versions of it made for them. Some applications like shoes will not utilize this material in a pure form, but may use hybrid woven versions. I like versions of it woven on the bias, as it lends a slightly more tech look, increases tear resistance and strength, and adds a 90s vintage look.

Which variants? Dimension Polyant’s VX line of fabrics are neat. I used VX51 for backpack panels while sewing at Mystery Ranch. VX21 is VERY common with backpackers. DP also make a hybrid fabric which utilizes Dyneema for higher overall strength. I also use Cuben a bit, from my 7.51-gram ultralight wallet to a back-to-basics hike/backpack I made from 2.4-Oz Cuben. The whole pack weighs well under a pound, which is approximately not much at all.

So that’s UHMWPE. It ain’t Tyvek, it’s expensive, and it’s a little hard to work with, but it’s pretty flippin’ incredible. Go check it out next time you’re in a super-exposed and remote part of the planet, trying to survive on only the basics as you brave the elements. You’ll probably find there’s nothing better.

Further reading

If you’re keen to explore more UHMWPE, there are a few places to play…
Dyneema and Dimension-Polyant both have sites about particular versions of the fabric, and Wikipedia is helpful as always.

For some lists of products available, check the ultralight forums and blogs. TenPoundBackpack is great, as is BackpackingLight.

Or click any of the packs shown above for makers and their info. Happy hunting!

  • http://www.sygyzy.com/ David

    Great post and excellent introduction to a category of bags our readers probably are unaware of. The whole backpacking light community is really into this stuff. They are all about weight, weight, weight. I have a Gossamer Gear Mariposa Plus and it weights 632g for the medium. It is like a 70L (est) pack. The problem with all these lightweight fabrics is you really give up comfort. They are all built like basically large deep sacks with some flimsy (sorry, light) waist belts and shoulder belts. If you threw on a Deuter or Osprey pack then put on a UHMWPE pack, you would think you went backwards in time … when in reality, you are using the latest tech. You have to be really careful about weight limits or you can hurt yourself.

    • Ando

      Yeah, some really good points.

      Our theory is that over the next couple of years we’re going to see more ‘hybrid’ approaches, which take the core body of an ultralight, but trick it up a little with the harnesses and features. The only way this will happen is if UHMWPE moves out of being only for the core crowds, and more into mainstream, which our guess is that it will.

      • http://www.sygyzy.com/ David

        As with most things, I think balance is key here. If you gave a Dyneema or Cuben Fiber bag to a typical person, they would not like it at all. Where it excels is when you are carrying small loads so it’d be perfect for a daypack or a city bag. Imagine a highly packable bag that you can stuff in your carryon, then take out when you are walking around a new city you’re visiting? No matter how hard I try, my Jansport isn’t going to pack small.

        I think companies like GoLite and Boreas Gear have the right idea. Their stuff isn’t quite ultralight but they find a nice medium between weight and comfort.


    Regarding the strength, tear, and abrasion resistance of these fabrics, which are claimed to be ridiculously high….is that purely for their given weight, compared to other fabrics of the same weight?
    Meaning, would this type of fabric match the strength, tear, and abrasion resistance of, say. 1000D Cordura?
    I just ask because I’ve seen a few reviews of tents made of fabrics like Cuben fibre which have talked about how amazing the fabric is, but then said how much care needs to be taken with pitching on rough ground because holes can appear quite easily.
    If the results are based on their given weight then I would be more interested in seeing the same technology applied to some heavier fabrics to make them truly indestructible.

    • http://www.fromhighabove.com John Canfield

      – The strength is high, period. Certain weights of Cuben will be less durable, but the durability is only added by design. In a situation where you are building a fly for a tent, abrasion resistance is not as important. This is the future of fabric, purpose built. I would estimate the 2.4oz/ yd Cuben I have worked with recently is more abrasion resistant than 1000d Cordura. I wont estimate data here, it is simply from experience. Heavier weights of the fabric would easily be more durable than 1000d or ballistic simply due to the fiber density. This stuff is comically strong.

      To address the tent you referenced, there is some truth to the concern. It is important to understand that part of what makes this stuff so light is the mylar bread that makes up the Cuben sandwich. Mylar is the stuff that covers your windows in the winter, and you might know, it is crazy strong! When you tear it, however, it propagates. The Dyneema threads stop the tearing, but in low Dyneema count layups of the material, holes may still appear.

      Cubic Tech makes heavy weight products that are also unbelievable. Truly wonder materials entering the market these days.

      • BAGMAN

        Thanks for that John…just the kind of answer I was after.
        I’d be keen to get hold of some samples of different weights of these fabrics, but as usual I’m sure there will be no suitable UK based sources. :[

  • Valter Neiva

    Im glad you bring this! I am always divided betwin the super technological and full of features urethane coated 1000d cordura U.S hand made in small factory backpack that last you a lifetime and the pragmatic and super technological Cuben Fiber, non woven Dyneema, Pro Silnylon, Mld, eVENT, etc… Space age backpack that attract me but do not last you a lifetime (you decide, sturdy bad ass vs lightweight bad ass). Please help me finding the truth i like them both!! I have too many bags now, fom made in usa 1000d cordura to cuben Zpacks and cilogear daypack, i will continue to search the ultimate bag that never leaves me and replace all the others.

  • http://www.blueridgeoverlandgear.com/ matt

    Great post,
    I am not ready to give up the 500D/1000D cordura yet, But I played with Dyneema and wile I like it. I don’t see where it is as well rounded as the Cordura fabrics. but some of the hybrid may change my mind.

  • David Millsaps

    You gotta see the Tom Sachs Mars Space Backpack by Nike. Its sailing cloth and material from space suits!

    • http://www.bellroy.com ando

      Haha, that header image is part of that whole collab. Click it and you’ll see the rest 🙂

  • Valter Neiva

    Yes, like it very much! Must be limited and expensive. White is for space travel!

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  • Jon

    UHMWPE in pellet form is actually cheaper than nylon,. The problem is that the super long chains that give it that high molecular weight also make it very viscous when melted, and raising the temperature causes the long chains to break, loosing the properties you want. This makes it expensive to process, and makes many designs impossible. Other problems is that it softens and loses all the good properties at around 100c, and expands a bunch when heated. It is also really hard to machine. That is why despite being more expensive, other materials are used.


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