The Beta

Discussing the technical background and innovation of SlingFin.

Tent Fabric 101: Nylon vs Polyester vs Dyneema/Cuben

Tent Fabric 101: Nylon vs Polyester vs Dyneema/Cuben
Tim Hunt - Friday, November 23, 2018

As in all aspects of tent design, fabric selection is a balancing act.

Different materials have unique strengths and weaknesses and selecting the “right” fabric is really about choosing which compromises to make. Do you want it to be light, strong, or inexpensive? You can pick two, but you sure as hell can’t have all three. A common assumption is that by buying an expensive product, you’re automatically getting the “best”, most durable product. This may be true for hammers, but for fabrics and tents, there is no “best” option. You could pretty quickly trash a fancy sports car on a dirt road that your late 90s station wagon could handle with ease. It’s the same thing with tents. A top of the line tent for thru-hikers would probably implode in winds that even a basic four-season tent would shrug off. Fabric selection is similar in that before designers make a choice, they have to explicitly decide on the goals for the product. The same is true of people who are purchasing tents. Are you going to be on exposed mountains where you’ll die if your tent fails in a storm? Are you going to retreat to your van as soon as it starts drizzling? Once the parameters have been established, the optimal fabric choice is often clear.

It’s unlikely that you’ll be confronted with a decision between two identical designs with different fabric choices. In fact, your fabric of choice will almost certainly be pre-determined by the kind of shelter you plan on buying. Rather than serving as a buying guide, this article is intended to provide users a very basic level of understanding of the strengths and weaknesses of the most common fabrics used in tent and tarp design: nylon, polyester, and DCF (Dyneema Composite Fabric, formerly known as Cuben Fiber).

Editor’s note: This is part of an ongoing series aimed at providing users with detailed information about design, materials, and construction, so you can make informed purchasing decisions to best suit your needs. If there’s a topic that you’d like to know more about, let us know at thebeta@slingfin.com. Header image is compliments of Rainy Pass Repairs. Thanks!  

Nylon

Nylon is by far the most common material used in tents. It was originally developed by DuPont in the 1930s and was used extensively for parachute production during WWII. It is the standard for the majority of outdoor products, from tents to apparel. This is largely due to its good strength to weight ratio, good abrasion resistance, and relatively low price.

Strength

Nylon has a much better strength-to-weight ratio than polyester, which is the main reason it is usually the fabric of choice for tents. Much of nylon’s strength comes from its inherent stretchiness, which can be a blessing and a curse. Because nylon stretches, it distributes stress over a larger area than less stretchy (we say more “stable”) fabric would. For example, if a guy point were attached in the center of a fabric panel on a tent’s fly on a 1” x 1” reinforcement, the surrounding fabric would stretch, and the stress of the guy line being pulled would be distributed over a much larger area than just the 1” x 1” reinforcement. If, however, the fabric does not stretch, all the force is concentrated at the reinforcement, leading to much higher stress on the fabric and a higher likelihood of tearing. Another benefit of fabric stretch when designing a tent is that it works better for shaped 3-dimensional panels.

Nylon’s stretchiness has a downside, however. A fly made of less stretchy fabric (e.g. polyester) can achieve a more aesthetically pleasing pitch, as much of the wrinkliness in the fly is caused by nylon stretching along its bias (diagonal with respect to the way the fabric was woven). Fabric that does not stretch as much reduces that issue.

Abrasion Resistance

Nylon is the most abrasion resistant of these fabrics. This is generally more of a consideration in apparel design, but parts of your tent will likely be exposed to abrasion (think floor, pole ends and clips). These can become failure points if the fabric abraids enough to weaken it.

UV Damage

Nylon is susceptible to degradation from UV exposure. This is primarily an issue for mountaineers who use their gear at high elevations where the UV index is very high. It also creates long-term durability issues for core users who use their tents several weeks out of the year for many years. Polyester and DCF do not degrade as much as nylon when exposed to sunlight for extended periods of time. However, any lightweight fabric will be more susceptible to UV damage than a heavier equivalent. Thicker diameter fibers mean much of the inner part of the fiber is protected from the sun. Even as the outside degrades, the inside will remain intact longer. UV radiation penetrates farther (as a percentage of total fiber thickness) into smaller diameter fibers. There are fabric coatings designed to lessen the effects of UV radiation on nylon (Our ET70 fabric, for example), but for users who treat and store their tent with care, UV damage will still probably be the limiting factor in a tent’s lifespan.

Water Absorption

Nylon absorbs water, which poses several problems. In addition to weighing more, wet nylon is far stretchier than dry nylon. In the field, this means that a nylon fly will sag when exposed to moisture (from precipitation or high humidity) which translates to late-night trips outside to tension the fly to keep it from sagging onto the tent body. Again, coatings can help mitigate this issue (look for both side silicone coated fabrics instead of PU; more on this in future articles). While polyester also absorbs some water, it absorbs much less than nylon, and will maintain tension better when wet.

Polyester

Due to its low price and poor strength to weight ratio, polyester is generally confined to the pricepoint and car camping tent market where weight is not a design consideration.

Tear Strength

Polyester has very low tear strength when compared to similar denier nylons. To achieve comparable strength to nylon, designers must elect to use much heavier, thicker polyester. Car camping tents can afford to use heavier fabrics to compensate for poly’s lower tear strength, whereas tents designed to offer more severe weather protection can’t make the weight sacrifice needed to use polyester instead of nylon. That being said, polyester does have some applications in some lightweight tarp shelters, where the fabric is not under as much stress as it is in traditional tents.

Stability

Polyester has much less stretch than nylon, and flies made of polyester pitch well due to its stability. Again, aesthetic considerations are often less of a priority in high-performance backpacking tents, and are more relevant to making a car camping tent pitch well with minimal fuss from the user.

UV Resistance

It is generally assumed that polyester is more UV-resistant than nylon, although this belief is based on dated research by DuPont into which material is better for curtains; the study was performed with the fabrics behind glass (to simulate windows) and is only marginally applicable to outdoor equipment. Anecdotal evidence seems to support this, however.

Across all fabrics, however, including polyester, fabric thickness and color play major roles in determining UV resistance. Especially for lightweight fabrics, the color and denier of the fabric will likely make more difference in the fabric’s long-term UV resistance than the composition of the fibers.

Poly is a popular fabric for sails and other applications where low stretch is a priority, and while its resistance to UV damage and low water absorption make it a theoretically desirable material for use in shelters, it cannot achieve adequate strength at the low weights consumers demand in most high-performance tents. Polyester’s applications in tents are fairly niche, where strength and weight are lower priorities, and keeping the cost down is more important.

Dyneema Composite Fabric

Dyneema Composite Fabric, or DCF, is the new kid on the block when it comes to tent fabrics. It used to be called Cuben Fiber, but the name was changed to Dyneema Composite Fabric when Dyneema acquired Cubic Tech, the company that makes the material. Many people still refer to the material as Cuben Fiber.

First, because I know there are some sticklers out there who will call me out on this, I am aware that some folks would argue that DCF is not technically a fabric. If you’d like to mince words, yes, it’s really a composite comprised of a nonwoven ultra high molecular weight polyethylene matrix laminated between two layers of polyethylene terephthalate film. But since it’s used interchangeably with woven textiles in outdoor gear (and “fabric” is quicker to type), we’ll group it in with the fabrics here, and I invite all those who think I’m a Russian troll sowing discord in the outdoor community by mixing materials definitions to get in touch with me at thebeta@slingfin.com. DCF is made by sandwiching Dyneema fibers between two layers of film (similar to Mylar). The Dyneema fibers are not woven, and are usually laid out at 90˚ angles.

Strength

Dyneema (a brand name for ultra high molecular weight polyethylene, or UHMWPE) is incredibly strong for its weight. No other material currently used in tents comes close to the tear strength of DCF on a per weight basis. Thus, DCF fabrics can achieve the same strength as nylon at a much lower weight. Despite its strength, DCF has almost no stretch. Dyneema’s lack of stretch and high strength to weight ratio makes it a highly desirable material for sails and numerous industrial applications.

DCF’s strength has some limitations, however. Seam failure from needle hole expansion is a common issue with films and nonwovens, so seams have to be bonded and/or hot taped. Tape adhesives are often a weak point and can degrade before the rest of the shelter wears out. It helps to put the tape on the inside (which is standard practice for most manufacturers) to lessen its exposure to UV radiation.

Waterproofing

DCF is inherently waterproof and doesn’t absorb any water, whereas both nylon and polyester wovens rely on a chemical coating (usually PU, silicone, or PE; we’ll talk about them in future articles) to make it waterproof. Coatings add weight and are prone to failure, so eliminating them means a lighter finished fabric with better longevity.

UV Resistance

DCF has much better UV resistance than nylon. It won’t degrade and weaken under repeated exposure to sun the way nylon does.

Abrasion Resistance (or lack thereof)

From a functionality standpoint, DCF’s Achilles heel is abrasion resistance. Since the outer layer of DCF is actually Mylar (the Dyneema fibers are on the inside, remember?), it is extremely vulnerable to abrasion (if you’ve ever tried to use an emergency blanket more than once you’ve experienced this firsthand). Ultralight enthusiasts may have noticed that DCF stuff sacks don’t last nearly as long as nylon ones, and the same is true for DCF backpacks. For most shelter applications, especially the simple tarps favored by the thru-hiking community, this isn’t much of an issue. Where this potentially becomes a problem is when companies use DCF in traditional tent construction. Tent pole clips and pole hubs can be more than abrasive enough to wear through a DCF fly when the tent is being buffeted by wind, especially in dusty areas where grit amplifies the effects of abrasion. My expectation is that unless the abrasion resistance issues can be addressed, DCF will only get substituted for nylon in currently available double-wall tent designs primarily as an UL statement piece, purchased by those with lots of money and not enough time to do their homework. Considering that switching out nylon for DCF in pre-existing double wall tent designs can push the price close to $1000, it's difficult to imagine true double-wall semi- or fully-freestanding DCF tents being a viable option for ultralight hikers, when purpose-built DCF shelters from cottage brands weigh less, provide much more livable space, and are stronger, all at about half the price.

Price

DCF is a fancy new space-age material with a price tag to match. At wholesale, $5/yard is considered expensive for high-quality nylon. For comparison, DCF rarely costs under $20-$30/yard. This is why DCF is generally found in less labor-intensive products (packs, tarps) from direct-to-consumer companies that don’t have to build wholesale margins into their pricing. Until someone develops a product that can compete with DCF’s strength to weight ratio, it’s unlikely that the price will fall. It’s prohibitively expensive for many consumers, especially considering that the weight savings are diminishing as lightweight nylons improve.

DCF is not a panacea for durability concerns in lightweight shelters. It does, however, mark a pretty significant leap forward in shelter materials. While its applications are fairly niche due to its astronomical price point and poor abrasion resistance, it does certain things better than any other material out there. Expect to see more of it in the future as ultralight backpacking moves into the mainstream.

There is no magic in shelter design. Every choice involves making sacrifices in one or more areas, and there are no perfect solutions. Nylon’s well-balanced characteristics make it a good choice in most outdoor applications, but, like every material, it has its share of shortcomings. Improvements in fabric weaving and coating technology mean we can expect to continue seeing incremental improvements in materials, but nothing radically different is on the horizon (to the best of my knowledge), so this is what we have to work with for the time being.

Hopefully, this has provided you with a little insight into tent fabrics, and will improve your understanding of the shelter options available to you when it comes time to pick your next adventure home.

Bengt testing fabrics in the SlingFin lab.

 Bengt testing fabrics in the SlingFin Lab.

 

Copyright SlingFin 2018 under Creative Commons License: okay to use with attribution. Please link to this article if quoting or reusing.

 

Tim Hunt has thru-hiked the PCT and AT, the GR20, and the TMB. His favorite food is butter. In addition to backpacking, he enjoys mountain biking, road biking, rock climbing, bike touring, trail running, whitewater kayaking, ice climbing, alpine and nordic skiing, snowshoeing, raft guiding, canoeing, mountaineering, and surfing. He’s always looking for ways to gratuitously combine as many of those activities as possible into one trip.