Durability of Cuben Fiber?

I have a cuben bivy I made for personal use over a year ago, and it has probably about 40-50 nights on it, and it still looks fine. I always clear the area of rocks where I am going to sleep, and sometimes use a groundsheet, but I don't really baby it. Its a bit dirty now, but still in great shape.

Are there punctures or fibers coming loose? I know what sil-nylon and tyvek look like when I use them for 50 nights, and it's usually, as you say, just fine.

It depends on the kind of cuben fabric. There are different grades, some which have more dyneema fibers in it, some with a thicker mylar film and more dyneema in it. Then there is the reinforced stuff with the extra poly fibers on the outside (used most for packs, and the heaviest).

I like the 1 oz per square yard stuff because i think it's more truly durable and long lasting, it has the thicker mylar film and more dyneema fiber. However, some people with experience swear by the thin, lightweight, and lower dyneema content Cuben fabrics. Richard Nisley did some tests and analysis and found that the lower weight cuben fabrics start to get observable damage just from repeated folding and stuffing–damage that could compromise the "waterproofness" of it.

I don't have any experience with the very light weight stuff, so i can't say for sure either way, but i just feel better with the heavier weight stuff. Some might say, then why not opt for high quality silnylon which is only slightly heavier, but much cheaper? Well, one, the 1 oz stuff is stronger and should last longer than even the best silnylon, and two you won't ever have to re-waterproof it like silnylon (eventually the silicone comes off) and for my purpose that is a big consideration.

I'm looking at an MLD Bivy, which appears to be .75oz. I wish it was the heavy-duty stuff, but I'm considering buying used and not custom-ordering.

I think because of how lightweight this fabric is, I have to pass on the tempting gear swap offer. The folding/packing damage is something I was concerned about in particular, as picking good camp spots is something I'm fine doing.

For a long-distance trip in unfamiliar territory, including prickly Arizona and Nevada, I think silnylon + tyvek are going to be my old standby materials.

Cuben is a very strong material for its weight. However, it is vulnerable to puncture and abrasion.

I don't have a Cuben bivy, but I would be reluctant to get one as I don't use a ground sheet and tend to camp above tree line on coarse gravel… or even on smooth granite sometimes. I am concerned it will puncture if the cuben is on the bottom and then leak.

I took 3 new Cuben items on a seven day backpack/climb a few weeks ago. The cuben rain kilt was used twice and came back with a hole in it where I sat on a rock during a break. The cuben tarp came back without any damage as it was never in contact with rock. My cube day pack came back with several holes, abrasions, and a 1" tear after one day of use.

The good news is it can be patched easily with stick on cuben tape. However, I think the cuben day pack used for climbing may have been a mistake as it does not look like it will hold up.

Bill D

Most sacks are made from some pretty thin material and I have a few that are in poor shape. I have several pieces of Cuben gear that have held up well, but I am not hard on gear. I have my doubts about most fabrics holding up when using them as ground sheets. I have a Cuben poncho/groundsheet but rarely use it as a groundsheet because I can usually get by with a piece of polycro.

Joe Velasco used to state his Cuben packs would hold up for one thru hike, but he is now using a lot of Cuben hybrid material. I don't know if he has changed this statement in his website.

Yeah, I can see the merit of cuben fiber, but I do not see it for on-the-ground use.

Since I'm planning on seeing deserts, mountains, and beaches this fall, I'm going with a Tyvek bathtub groundsheet to fight abrasion. The silnylon bivy I have will do fine in it, even though it's not remotely as waterproof as the cuben. Plus, at $7 from Zpacks, how can I complain?

Too bad, I guess I have to wait 5 years for the next miracle fabric if I want to shave off 10oz from my kit.

Thanks for the responses and testimonials!

I have the Zpacks Multipack, which is made with the heavier, Cuben hybrid stuff. It seems pretty bombproof. But then again, it goes on my waist and in front, so it's not going to see a lot of abrasive action unless i'm squeezing by something which scrapes it.

A lot of these issues with Cuben fabric (including outrageous prices) could be solved if they stopped using mylar film to sandwich the fibers, and went with UHMWPE film to do so. It would be much, much tougher stuff. And it would be easier to bond, wouldn't have to go through that plasma treatment crap which is a big reason why it's so expensive. Since dyneema IS basically UHMWPE, the film and fibers could be bonded via heat and pressure, much more simple.

I suspect they went with mylar (polyester essentially), with making Cuben fabric because it was originally for Sails and sails by nature have to be very U.V. resistant. Mylar is inherently more U.V. resistant than virgin UHMWPE film. However, the latter can be treated to make it more u.v. resistant.

Why hasn't this transition already happened?

Probably because Cuben fabric is primarily manufactured for the boating industry, and not for us backpackers–we're still just a side venture and small slice of pie in the grand scheme of things, and like i said, mylar is more inherently u.v. resistant which is a plus for sails. Sails don't have to be as abrasion resistant either, they are just catching wind and not rubbing against stuff.

I have a zPacks Zero with at least 100 days of trail use on it to include a lot of off trail hiking in deserts and boulder scrambling in canyons. It has no rips, tears, or holes. I attribute that to care and a bit of luck.

As the grandchild of a several-decade board member of U.S. Sailing, I'll see what I can do.

Haha, change the world Max, change the world (or at least the cuben fabric world).