- Feb 2, 2019 at 2:06 am #3576335
I didn’t realize that .51 Dyneema with a solid groundsheet underneath was so susceptible to abrasion, but I believe what you guys are saying. You both seem to know materials a lot better than I do.
So what’s better, a 4000 mm 20d silpoly or a Mountain 30d silnylon? I mean for durability and long term waterproofness?Feb 2, 2019 at 2:19 am #3576337
NMFeb 2, 2019 at 3:38 am #3576351
Monte, I would choose the 30D fabric and coat it myself. If it leaked, then I would recoat it. But, that is looking for WATERPROOF without saying to what degree.
I don’t really expect to be in a situation where I cannot find a dryer piece of ground to set up on. I always choose a slight mound somewhere, often near a tree. If I can keep the majority of the condensation from coming through, I would be happy. I usually camp with a small piece of plastic ground cloth under a tarp. I do not rely on the floor to keep water out, but rather I rely on knowledge of terrain runoff and overhead coverage draining the runoff away from me. Tarp camping 101. Sometimes, getting to a camp site and setting up in the rain is wet work. But choosing proper ground is as important as checking for widow makers.
Planning ahead is important. Having a pee bottle is important. Having enough water for breakfast is important. Keeping my quilt and sleeping cloths dry is important. Worrying about if the floor will leak is not something I think about.Feb 2, 2019 at 4:01 am #3576354
“So what’s better, a 4000 mm 20d silpoly or a Mountain 30d silnylon? I mean for durability and long term waterproofness?”
All else being equal, poly is slightly more abrasion resistant than nylon so a 20D poly might equal a 25D nylon. So a 30D nylon would be slightly ahead than 20D poly but pretty comparable. There are other factors here too, like the threadcount, ripstop and calendaring.
For the coating, sil improves tear strength but is slippery and can’t be seam taped, while PU improves abrasion resistance but lowers tear strength, can be seam taped, as is not slippery. Floors are subject to more abrasion then tear strength, so I think PU is better as long as you don’t go crazy with it (PU4000 is a bit much). The best is a blend where you have PU on the inside so it’s non-slippery and can be seam taped, and then sil on the outside to boost HH without an excess penalty to the tear strength. So a sil/PU poly or nylon is ideal. The sag of nylon doesn’t really matter here.
There’s a lot of hairs that could be split, but generally any 20-30D nylon or poly that is sil and/or PU coated is going to work pretty well long term as a floor if treated reasonably well. If you go down to 10D then it’s getting sketchy and you need to treat it very well or use a groundsheet. So the lightest woven materials (e.g. 20D) that will hold up reasonably well for the long term without a groundsheet weigh about 1.2oz/yd. Below that you’re either very careful or in for a shorter lifespan.
With DCF, I think the variants with the .18 mylar hold up about as well as these 10D woven materials – you can get a decent life out of it if you treat it very well, but it’s pushing it and most folks will either have a shorter life or use a groundsheet. So it’s hard to see an advantage of DCF because the most commonly used DCF for a floor (CT2E.18) weighs about the same as a 10D floor (1.0oz per yard) and it lasts about the same but the DCF is much more expensive. So it’s just more expensive than 10D for no real advantage. Or compared to a 20-30D floor, it’s hard to argue that it’s not “stupid light” to opt for CT2E.18 since you save less than 1oz but with a cost of $60 and a shorter life for your tent.
So the only variant of DCF that I think makes sense in some niche applications for a floor is CT1E.18. That is the lightest variant with the .18 mylar and I think it will hold up about the same as the other .18 variants because it’s really the mylar that limits the lifespan. So it’s still expensive and borderline for the durability, but at least you are saving an appreciable amount of weight. Thus it can make sense if you are want to be on the bleeding edge of ultralight. A nicely sized 2P tent has about 4 square yards in the floor, so this would save 2oz over using 1.2 oz 20D fabrics, whereas the more commonly used CT2E.18 (same thing except 2x dyneema) weighs 1.0 oz per yard so it only saves 0.8 oz.
Circling back to Big Agnes, they are using CT1E.08 – the same thing I just suggested except with the 0.08 mylar. That saves a further 0.8oz off a 2P tent (4 yards at 0.5oz/yd rather than 0.7oz/yd) but with a much larger durability penalty. With CT1E.18 you could plausibly use it without a groundsheet if you’re careful, whereas with CT1E.08 you’re almost certainly going to have leaks in a two dozen nights if you don’t use one. So if you take the view that the .08 mylar DCFs need a groundsheet, then CT1E.18 becomes the lightest possible material for a floor and thus worth considering for bleeding edge ultralight tents.Feb 2, 2019 at 9:06 am #3576372
sil improves tear strength but is slippery and can’t be seam taped,
Sorry Dan but that is false. I have been taping the seams on my silnylon tents for about 8 years now. You can’t use the same tapes as you would use on PU, but there are siloxane tapes which work on silnylon even better than PU tapes on PU.
Caveat: the siloxane tapes are a bit more expensive, but you don’t use a lot. I prefer the transfer tapes as that helps match the stretch.
CheersFeb 2, 2019 at 12:35 pm #3576379
“All else being equal, poly is slightly more abrasion resistant than nylon”
Dan, I think you have it backwards. Nylon is slightly more abrasion resistant than poly. Here is one study and an overview.:
Note they are testing 600D poly vs 500D nylon. Basic results excerpt:
<p class=”font_8″>The test result is:</p>
- <p class=”font_8″>600D Polyester: Moderate abrasion after 25,600 cycles</p>
- <p class=”font_8″>500D Nylon: Very slight abrasion after 25,600 cycles</p>
- <p class=”font_8″>1050D Nylon: Very slight abrasion after 25,600 cycles</p>
Basic results excerpt:
Nylon is exceptionally strong, even stronger than polyester.
Nylon and polyester are both abrasion resistant and resistant to damage from most chemicals. Nylon is also resistant to oil.
Both are flammable — nylon melts then burns rapidly; polyester has a higher flammability temperature, but melts and burns at the same time.
They also tend to be wrinkle-resistant, polyester more so. It doesn’t stretch of shrink, and is a crisp, resilient fabric whether wet or dry.
Both nylon and polyester have a relatively low moisture absorbency, though nylon’s is lower.
I would note that nylon tends to stretch more when wet than polyester. The primary popularity of poly is cost/ease of manufacture. There are other studies I won’t bother to list… And as you say, the exact fabric treatment can vary the characteristics a lot.
Anyway, for these tents I agree. I would choose a lightweight nylon fabric for the floor. Something that can be maintained easily due to the light weight. But BA seems to think extreme weight savings is king. Unfortunately, the .51 DCF is not the best choice for floors. The .8 would be far better even if it cost a bit in weight.Feb 2, 2019 at 5:21 pm #3576404
[Did your post break the formatting of the rest of this page?]
“Sorry Dan but that is false. I have been taping the seams on my silnylon tents for about 8 years now. You can’t use the same tapes as you would use on PU, but there are siloxane tapes which work on silnylon even better than PU tapes on PU.”
Interesting. If this works so well, why do none of the major companies that make silnylon tents use this? Simply the cost?
“Dan, I think you have it backwards. Nylon is slightly more abrasion resistant than poly. “
Thanks for this. A tough thing with the internet is that there’s a million sources for everything and they often conflict, plus there’s so many potential confounding factors in many of the tests (e.g. threadcount, ripstop, calendaring, cire coating, type of nylon etc). I did some more reading and found this academic paper which is ancient (1954) but seems like a robust study as they controlled for seemingly all of the above mentioned factors and tested a wide range of materials. They do have a slight edge for nylon as well, so I acknowledge that you are correct here.
Since we are discussing applied applications here, it seems worth considering that nylon has much lower UV resistance. That wouldn’t really matter for a floor, but for tents/tarps in general, there is good reason to think that nylon more than loses its initial strength advantage within the reasonable lifespan of a tent. For example, Nemo Equipment write: “Nylon is stronger… except that in the presence of UV, it will break down and start to degrade much faster than polyester. Polyester naturally inhibits UV. Although the fiber may be weaker at the start, it holds up better over time.”
“The primary popularity of poly is cost/ease of manufacture.”
In the lightweight backpacking world, I think the growing popularity of poly is due more to the lack of sag/expansion when wet, rather than cost. This is particularly appealing in trekking pole shelters when the design tends to have larger panels that are more affected by the 4% expansion of nylon. Perhaps poly is cheaper overall, but either way tent makers are getting this stuff for $3 – $4 per yard so the difference in materials cost to a shelters price is minor. When companies switch to poly, we generally don’t see lower prices (e.g. Yama, Lightheart etc)
Anyways – we are supposed to be talking about DCF and Big Agnes new tents so I’ll close by saying the UV resistance of DCF is great too.Feb 2, 2019 at 6:41 pm #3576412
Yeah, both nylon and poly have high UV resistance with poly having an edge there. Not usually a concern though. I’ve had more damage stretching over poles than from UV damage. A simple flat tarp (1.5oz/yd) lasted well over 14 years before splitting where the pole was supporting it. Unless it is left out in direct sunlight for a year, you really won’t notice the difference Nemo is talking about.Feb 2, 2019 at 8:55 pm #3576435
If this works so well, why do none of the major companies that make silnylon tents use this? Simply the cost?
I do not know, but I suspect that it is a combination of operational cost and simple ignorance. For the latter, everyone ‘knows’ that ordinary seam-seal tapes don’t work on silnylon, so they give up. For those who know about siloxane tapes, the curing time is commercially unacceptable. To explain:
A tape for PU uses an adhesive (often acrylic) which ‘sticks’ to the PU. It may stick poorly or it may stick well, but it remains an adhesive bond. Normally the adhesion is immediate – it can be called ‘tack’. Mfrs like high-tack tapes.
A siloxane tape is very different. The initial adhesion or tackiness is moderately poor by comparison, BUT the siloxane adhesive undergoes a reaction when placed on a silicone coating, and over a period of about 3 DAYS (72 hr) it chemically bonds into the silicone coating. After this time it is very hard to separate the tape from the silnylon. If you use a transfer tape (an adhesive layer without a polyester carrier), you end up chemically bonding silnylon fabric to silnylon fabric. You have to destroy the fabric to get them apart once cured. But it takes 72 hr for the curing.
This is probably the same reason mfrs ship silnylon tents with a tube of silicone sealant rather than sealing the seams themselves: they can’t afford the 24+ hrs for the sealant to cure. Me, I can afford the wait.
CheersFeb 3, 2019 at 1:10 am #3576474
“For those who know about siloxane tapes, the curing time is commercially unacceptable”
Interesting. Thanks for this. Myself I prefer seam sealing because it is applied externally so it stops water from soaking into the seams, whereas internal seam tape only stops water at the last minute before it soaks all the way through. External seam tape that adheres well would be fine, but is typically unsightly. From commercial standpoint I see why PU tapes are appealing (many users don’t want to seam tape/seal), and then from a user standpoint I’d likely just seam seal. Do you find there is an advantage this siloxane tape over seam sealing?
“….both nylon and poly have high UV resistance with poly having an edge there. Not usually a concern though.”
I think it’s too generous to refer to nylon’s UV resistance as high, and polyesters edge as “slight”. I would characterize nylon’s UV resistance as “poor” and polyester as “outstanding” with the difference being “massive”. Or in the words of MoonLight tents, polyester’s UV resistance is “better than nylon by a long shot”.
Here’s a recent (2013) scientific article that compares the effects of UV exposure on the tensile strength of nylon 6,6 vs polyester:
The effect of UV degradation on toughness of nylon 66/polyester woven fabrics
To investigate this, they made custom fabrics with nylon as the warp thread and polyester as the weft. Then they exposed those samples to UV and tested the tensile strength in warp and weft. The amount of UV exposure might not be relevant to real world conditions, but since the nylon and poly are being exposed equally, it gives insight into their relative degradation.
First, here are the results for nylon:
We see that their brand new nylon has a tensile strength of 1600 N, and that drops sharply with UV exposure so it’s down to 600 N after 14 hours and a mere 250 N after 28 hours. So when exposed to these conditions, nylon loses 85% of its strength. You can see it is also becoming brittle, as its stretch at the failure point is radically reduced from 30mm to 4mm.
Now here are the results for polyester:
The polyester actually has a higher initial tensile strength than nylon at 2200 N (which isn’t that surprising because these fabrics are more similar than everyone gives poly credit for) but let’s ignore this because perhaps they used a slightly thicker or better polyester or something. The main take away is the polyester actually gets stronger with UV exposure. It measures 2200 N initially and then 2400 N after 28 hours of exposure for a 10% gain. So nylon lost 85%, while polyester gains 10%. Thus you were to start off with nylon and polyester at equal strength, the polyester would wind up about 8x stronger after being exposed to these conditions.
Now of course nylon does have an initial tear strength advantage. I could be wrong, but everything I’m reading is that this is overstated and the difference is no more than 20% and that’s ignoring that nylon loses about 10-15% of its strength when wet, whereas poly does not. If we grant nylon a 20% tear strength head start, the polyester would still be 6x stronger at the end of this exposure.
Of course this might be a completely unrealistic amount of UV exposure that has no relevance to real world conditions. So is UV exposure a real problem with nylon tents? How much UV exposure a tent gets will vary widely, but I think there is good evidence that UV degradation is a real problem with nylon tents. In addition to my earlier quote showing Nemo saying that polyester is stronger over the normal lifespan of the tent, SlingFin writes “UV damage will still probably be the limiting factor in a [nylon] tent’s lifespan” while MoonLight Tents write “if you used both side by side for a couple of weeks the polyester would be significantly stronger than the nylon“. We also see Rainy Pass tent repair writing about nylon tents “the main issue that we see is UV damage or “sun rot.”
So I think it is clear that UV degradation is a major issue for nylon tents. I feel that much of the nylon vs poly debate has been overly generous to nylon as folks are quite to tout that nylon is stronger, without much regard for how (1) this difference is typically overstated and (2) nylon weakens substantially when wet and massively with UV exposure while poly does not. The ability of poly to maintain its strength over time and a wide range of conditions is a major advantage.Feb 3, 2019 at 3:27 am #3576500
I do not think that tests done under MASSIVE doses of UV is relevant. As I say, a tarp was used rather normally (around 30 days per year) under much more normal conditions (half sun, half shade) at higher latitudes roughly 40-50 degrees north and would never receive the amount of UV as described in 20 years of use, let alone one. I believe the test you quote was done in a 60 year test accelerator compressing the UV irradiation down to 1 year, but I don’t have access to the full paper to say for sure. And, there are usually differences in the strength of warp/weft directions. One is a “stationary” thread that is woven through by shuttle. Nemo is simply referring to the 1 year test cycle implying that this is “normal use” when it is not. This is all sales hype on Nemos part to sell their stuff.
This is not counting the coating of course. Much of the UV is picked up and dissipated by the silicone and PU coatings used for waterproofness. This applies to both fabrics. But this will be especially helpful to improving Nylon, but doesn’t really help poly. In general, you can expect a fly or tarp to last about 20 years of average use and be roughly equivalent to each other, ie, nylon will be stronger the first 5-7 years or so and then equivalent for around 5-7 years and then be weaker than Polyester for 5-7 years. Of course, this means maintaining the silicone coating. PU will not last that long, usually and cannot be maintained.
Nylon 6,6 is about 30-40% stronger than poly fabrics for the weight. Poly picks up much of it’s strength characteristics from a single long straighter chain of molecules with little cross linking. Nylon picks up much of its strength from long chains of molecules but also cross links them (often via hydrogen bonds.) Wetness can cause stretching and loss of strength by disrupting the hydrogen bonds. This is avoided by simply maintaining the silicone coating, though.Feb 3, 2019 at 4:58 am #3576512
First, I want to say thanks for this discussion because you obviously know a great deal about this stuff and this has been really good to get me diving back into doing more research.
“This is all sales hype on Nemo’s part to sell their stuff.”
As far as I can tell, Nemo exclusively uses nylon in their tents. So I don’t think they’d say poly holds up better as sales hype to sell their stuff.
“I do not think that tests done under MASSIVE doses of UV is relevant.”
Sure. I only cite this to show that whatever UV degradation is happening to nylon tents, is not happening to poly tents to nearly the same extent. But more generally I think it is clear that (1) UV degradation is a real problem for nylon tents and (2) poly solves that.
It’s also worth considering that low denier threads are much more vulnerable to UV degradation because they are thinner so the UV penetrates are larger proportion of the cross sectional area. Virtually ever study on the UV degradation of nylon has used much heavier fabric, so I suggest that low denier nylons experience much higher UV degradation that what is shown in the literature. I read a study that said this, but can’t find it now. I do read in this study “initially the rate of degradation in outdoor environment is higher and it shows some leveling over a period of time. This may be due to the fact that the outer yarns face the brunt of the exposure and more reduction in strength takes place in these outermost yarns as compared to the yarns embedded in the inner structure.” which if true would also mean that thinner fabrics are more effected than thick ones. Empirically this seems obviously true – a t-shirt left on the lawn for a month doesn’t fade evenly right through, but predominantly on the upper surface.
“Much of the UV is picked up and dissipated by the silicone and PU coatings used for waterproofness.“
I haven’t been able to find much research on this, but I do note that some tent manufacturers are looking to other coatings, such as Titanium Dioxide, because they write that UV exposure is a problem in the alpine environment for their PU nylon tents. While PU may improve things for nylon, I think it is clear that coated nylons still suffer from meaningful UV degradation within the reasonable life of the tent. Every modern tent has been coated with PU or sil, and yet we see abundant examples of UV issues.
“Nylon will be stronger the first 5-7 years or so and then equivalent for around 5-7 years and then be weaker than Polyester for 5-7 years.”
I think the cross over point occurs much sooner (e.g. I’ve cited articles saying it occurs in weeks or a few months) but regardless, we agree there is a cross-over point. I don’t see how this doesn’t lead to the conclusion that poly is overall a better choice for strength reasons. If you had to choose between two tents where one tent is good the entire time, while the other starts off very strong, then is good and then is borderline, that first tent seems like the wiser choice because you are never using it with as slim of a margin for error. Neither tent is going to fail in the first few years, but the nylon might fail near the end.
“Nylon 6,6 is about 30-40% stronger than poly fabrics for the weight.”
From your subsequent description it sounds like you know what you’re talking about, but do you have a reference for this? Typically I read 15 – 20% but the answers vary widely. For example, here is Dupont – a well respected chemical company – listing about a 1% advantage for nylon.
To sum up what we agree on, nylon 6,6 starts off somewhere between 1 – 40% stronger and this advantage diminishes over time so it is gone somewhere between a few weeks and 7 years.Feb 3, 2019 at 5:32 am #3576515
External seam tape that adheres well would be fine, but is typically unsightly.
Not entirely relevant or true.
For instance, sealing the seams on a bathtub floor: who is going to look or care? And that is a very important application.
If the seam is 3 mm wide total and the tape is 12 mm wide, you will have complete sealing even if on the inside. Reality is that sealing the inside with siloxane tape (this way) and then spraying the seam on the outside with some silicone spray is totally effective.
If you use a transfer tape (double-sided in effect) and use the same colour silnylon as the backing for the siloxane tape (on the outside) then from any distance you will not see the sealing strip. It will blend ‘seamlessly’ with the fly.
This is old technology: I was doing it 15 years ago. It works extremely well. But the 72 hr curing time kills it for commercial use.
PS: my nylon tents are still going strong after 15 years of field use too.Feb 3, 2019 at 2:35 pm #3576550
Though we are far afield of the BA tents, here is a reference (I couldn’t find the original group of tests, when I first explored poly). again from https://www.orientbag.net/single-post/2016/05/31/The-Fabric-Strength-Challenge-1
It shows a fair amount of testing between 500Dnylon and 600Dpoly. This shows about a 40% strength plus on nylon, even with the lighter fabric. I discounted this because some of the other tests I mentioned was closer to a 30% difference in strength, usually based on style of weave. Hence the range, despite the available documentation. (Damn windows 10 doesn’t search the same as Windows 7…computer problems again and I ain’t gonn’a spend all day sortin’it out.) Anyway, this is where I come up with the approximate equivalency in strength due to UV damage over at 10-14years or around 2/3 the reasonable lifetime of poly or nylons at around 20 years or so. I would guess you can get more life out of them, but again, the mechanical damage due to stretching causes more damage than UV damage on the majority of my tent/tarp equipment.
Anyway, as you say we can drop this discussion on this thread though you are welcome to respond.Feb 3, 2019 at 5:22 pm #3576573
In my quest to figure out what’s best, I looked at the gold standard (correct me if I’m wrong) in ultralight double wall tents, the Hilleberg Enan. Weighs 1050 gms.
Floor description: ’50 denier nylon. Double coated Polyurathane 12000, highly puncture and abrasion resistant.”
Fly description: “Kelron 1000 20d high tenacity Nylon 66. 3 layers of 100% silicone and treated for UV resistance during dyeing and coating. 3000mm.”
So I’m curious what you NASA scientists ( I mean that respectfully) think of Hilleberg’s choice of materials and the Enan tent in general?Feb 3, 2019 at 5:29 pm #3576576
“It shows a fair amount of testing between 500Dnylon and 600Dpoly. This shows about a 40% strength plus on nylon, even with the lighter fabric.”
A concern with this test is that they apparently just grabbed “some common fabrics” without regard for factors like thread count and coatings. So there are many potential confounding variables.
They do write “500D Nylon is about 1.4 times stronger than 600D Polyester” but their 600D poly is PU coated while their 500D nylon is not. That is a large confounding difference because PU has negative effect on tear strength. Polyester without this would certainly test higher. The other polyester that they tested with a PVC coating was 60% stronger than 500D nylon. Also, the high result for 500D nylon seems a bit odd considering it is almost 3x the result of their 400D nylon. Overall I think all of their results are substantially influenced by these other variables so it’s not really fair to boil the differences down to nylon vs poly.
Probably the most fair comparison in their test is between the 1680D nylon and 1680D poly since at least they are both PU coated. Indeed there is still a 40% difference here but I still don’t think we can conclude much in the absence of knowledge on the confounding variables like thread count, weave and thickness of the PU coating. Variation in the PU coating in particular could cause this difference even with two equal fabrics. I’m not saying that’s the case, just that it obscures whatever the real difference may be.
In general, it seems hard to find good sources on fabrics because so many tests are comparing a collection of fabrics rather than isolating individual variables.Feb 3, 2019 at 6:25 pm #3576585JohnBPL Member
@johnnyh88Locale: The SouthWest
A lot of these tests seem confounded and possibly irrelevant to low denier tent fabrics, which have different weaves and coatings. That said, I think the following is clear:
- Nylon is stronger than poly when using the same weave and coating
- PU weakens the tear strength
- Silicone coating increases the tear strength
- And that UV degradation may reduce the difference between poly and nylon (over time)
If a given denier and weave of nylon works for a tent, then I think any smartly designed and properly reinforced tent can also make poly work.
Wilderness Logics was working on a “polyblend” tarp material before the owner passed away. It seemed like an interesting concept. I think the fabric used a base of polyester with nylon ripstop grid? The idea was to have low sag when wet, with the nylon ripstop providing a higher tear strength. Big Agnes uses a “random ripstop” which they claim increases their fabric’s tear strength.
- You must be logged in to reply to this topic.