The current thread on the new Seek Outside lightweight prototypes has got me thinking about fabrics for durable packs. I’m tending towards the idea that boring old Cordura is being under-valued in the rush towards the sexy new laminates, but please check my logic and challenge any wooly thinking.
You frequently see claims that X-Pac offers weight savings over older fabrics like Cordura – for example here on Carryology: https://www.carryology.com/insights/insights-1/dyneema-vs-x-pac-ultralight-fabrics/
But is this really true?
With a good Cordura, most of the weight is in the tough face fabric (with its proven weave of strong 6.6 nylon), with modest weight in the PU water-resistant coating.
With X-Pac, weight for weight you get a lighter face fabric (which in many versions is of unknown provenance), with more of the weight devoted to the waterproof laminate and optional internal lining.
If you’re concerned about abrasion and durability, this means that for the same performance dry Cordura will always be lighter than dry X-Pac. So as far as I can see, any edge for X-Pac is restricted to performance in the wet.
Neither pack will be fully waterproof, so you’re going to have to use a trash-bag liner in both. In my experience this is enough to protect your gear. I have an ancient Cordura pack that’s lasted literally 1000s of days on the hill. The DWR is long gone and the PU coating is degraded, but although it leaks a bit through the tight weave my gear has never suffered inside the liner This is an extreme boundary case – most people don’t use a pack for 40 years – but functionally the leaking has been pretty much a non-issue despite the less effective PU waterproofing.
So what’s the payoff for the weight of the laminate? Sure, the waterproofing is more durable, but as I’ve argued, I’m not convinced that provides a significant practical benefit.
That leaves weight – with many people claiming that X-Pac is lighter than Cordura when wet. With both Cordura and X-Pac the face fabric is protected by DWR which will wear off, so both will absorb water after some use. The X-Pac will absorb a bit less, but only because the face fabric is thinner and less durable than a Cordura PU of the same weight.
Has anyone actually tested whether wet X-Pac is significantly lighter than wet Cordura of equivalent durability? The Cordura PU starts lighter, so there would have to be a very large difference in their performance in the wet before it became a meaningful issue. I simply can’t see where that difference would come from.And what percentage of our time do we really spend walking in persistent rain? Even here in the UK it’s relatively small, while in the SW US, for example, it’s trivial. The rest of the time, Cordura is lighter at any given level of durability.
Quality branded Cordura is inexpensive and much of it meets stringent military standards, It’s easy to source in a wide range of weights and colours, doesn’t fade in UV, has a nice hand, takes stitching like a champ, self-heals if you need to rip a seam, has no abrasion points like the X-Pack ripstop, and in my experience, is pretty much indestructible (for any use short of canyoneering).
But if you look at the specialist pack makers and the MYOG packs here, Cordura is rarely used these days – it’s all Dyneema ripstop (which seems to offer no advantages at all over Cordura), X-Pac and a couple of companies offering woven Dyneema (which we can’t source). I know that Cordura is not sexy and the newer fabrics must be easier to market, But perhaps we’re being too quick to abandon it?


