Industry

Carry Materials III

by , July 9, 2012

For a larger version of the image, click here.

Our second Carry Materials post highlighted the properties associated with various materials utilised in carry products but now it’s time to provide some insight on why certain materials have certain properties.

Fibers are woven to become fabrics to which a backing is added, resulting in better resistance to tearing, abrasion, water, etc.  These weaves come with different design textures and weight.  Denier is a unit of measurement for the linear mass density of fibers.  The higher the Denier the thicker the thread and therefore the heavier the fabric.  The fabric weave provides part of the material’s properties and the backing provides the other part.  The backing is either laminated or sprayed to the fabric.  A good example are fake leathers, which are extruded polyurethane.  They tear easily and don’t resist abrasion well but with the right backing they are much more durable.

The image above highlights different kinds of fabric weaves, as well as different types of backing that can be applied to the weaves to provide various properties.

  • M.S

    I was just thinking where the hell is the Carry Materials II and how did i miss it.. but it appears that it shows posted (4 posts) before the first one. Maybe you can fix this and bring it up so people wont miss it!

    Anyhow keep up the good work!

  • http://samh.net/ samh

    Good follow-up post, but the spelling errors on the graphic are abominable.

    • Ando

      Haha, go easy… Hadrien’s spelling in French is perfect. English is a second language, and one that he is doing a hell of a lot better with than my French!

  • http://mysteryranch.com Dana 3 Gleason

    Something I think needs to be explained is trade off on backing and the degradation of strength. People often look at fabrics with a heavy coating and think it makes it “bombproof” as one reviewer said when talking about the Noas pack made by Arc’ teryx that had a great PU coating on both sides. This is just not the case when it comes to tare strength. The more you constrict the movement of the weave in a fabric by adding a coating (that doesn’t stretch, I’ll get back to this) the more force is put on fewer fibers.

    Tare strength in a fabric is not only determined by the tinsel strength of the fiber it is made up of, but also it’s weave. A rip is stopped effectively in a fabric when it’s fibers bunch up together into a knot of many fibers collectively resisting the force being exerted on the tare. When you put a coating onto a woven fabric you are gaining the wonderful water protection of it as well helping the stability of the material so it doesn’t fray at the edges, but you are also constricting the individual fiber’s movements in relation to one another. If that “bomber” material with a heavy coating gets a hole in it and force is put on that hole the fibers around it wont group together to form a knot. The tare will just run because only one fiber at a time is taking the force exerted on the rip.

    Non-stretch films that are laminated to woven fabrics decimate the materials tare strength because they lock the fibers in place as does a very heavy PU coating.

    A polyethylene film (I think this is what is PE) can work well but are expensive and don’t always bond to the fabric reliably. Don’t get me started on this…

    PU coatings can very whether as well; a cheep polyester polyurethane (this shit starts pealing and rotting off the fabric with in a few months to years of use, polyether polyurethane much better and just a little bit more expensive (well worth it if you have a say), and polycarbonate polyurethane (expensive and the shit as far as PU coatings are concerned, but you have to trust the coater/converter because the machines have to be cleaned well so there is no contamination from the other two PUs.)

    Balancing a good coating vs. maintaining strength is an issue we at the Mystery Ranch have had to cope with for a long time now, and I could keep on going but it late and I have to catch a flight tomorrow. Maybe some other time.

    • http://www.taylorwelden.com taylorwelden

      Thanks for the super informative response, Dana.

      Two things…
      -As a full-time softgoods bag/pack designer, you work is an inspiration to me. It would be my pleasure to have a beer or coffee and talk shop and design/construction philosophy with you sometime.
      -Excellent points you’ve brought up, many of which people are not familiar with. This is exactly the kind of content we’re looking for at Carryology. Would you maybe be interested in a guest post sometime? Focusing on materials and/or construction perhaps.

      I think you and my friend Scott, also owner of a phenomenal carry business, would get along great and have much to discuss.

      Thanks again for your post. We welcome (and would love) any additional comments you may have.

      Taylor
      http://www.coroflot.com/TaylorWelden

    • Hadrien

      Wow. Some great input Dana. We actually bounced it around a couple of us to see what ideas it pushed…

      You’re absolutely right when you say the backing must be designed to work with the fronting, and this feels like part art part science. For the mass market stuff, most suppliers seem to shoot for the cheapest woven they can get away with (often so loosely woven you can literally see through it), and then just add a thick but cheap backing to give some sort of structure.

      I think your point about the different PU’s is really interesting. Because all the backings we call PU are actually TPU (Thermoplastic PolyUrethanes), I don’t think most of us pay enough attention to the differences within the TPU families (myself included). Like all ThermoPlastic Elastomers (TPEs), TPUs are essentially made of a hard and a soft plastic souped together in an orgy of chemical bonds. Depending on which plastics you mix in this soup, you end up with different properties. Before your comment, I’d figured everyone was just using Polyester-based TPUs.

      The most interesting idea in that comment for me is the concept of allowing stretch in the backing in a way that actually increases strength. Essentially, if you can increase the elastic properties of the backing, you should be able to better control strength by better leveraging the woven properties. Most materials increase in strength once they pass beyond their elastic limit, before going brittle and failing. I also wonder if that would be the case with these backing elastomers.

      The stuff Nike is doing with variable weaves in footwear could surely have relevance to carry. Or the ways bike makers are now custom laying carbon fibres before baking to allow different flex characteristics. Perhaps we could all start controlling for strength on one plane, and load control and stretch on another, just by specifying weaves. Haha, the mind races…

      It also has me wondering about the great inroads that mountainwear brands have made in stretch waterproof fabrics, where they must be getting their PTFE equivalent membranes to stretch quite a bit while maintaining water-tightness. Surely these could get ‘out of the way’ of the fronting weave to allow it to move and adapt with strength requirements.

      OK, can I ask just 2 questions while we have you writing…
      1) Do you have fabric mills bringing this sort of knowledge to you, or do you have to kick and fight for every bit of innovation you receive?
      2) Is there a sharing of this sort of knowledge through the armed forces bodies, or do they totally rely on their suppliers to know and spec these details?
      I’ve never designed for military, so I’m really curious :)

  • B.R.P

    I like Dana! :]

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