Tarp fabric resistant to hail and extreme weather

[Jon Solomon]

Thanks, Roger.

This thread is not as confusing as may seem. The takeaways so far would be:

1. Ripstop weave is not good for HH performance on silicone coated fabrics over the long term.

2. Ripstop weave increases tear strength in uncoated fabrics and in PU coated fabrics, but is unnecessary in silicone coated fabrics and, in light of #1, is actually detrimental.

3. Ripstop continues to appear in siliconized fabrics because it’s easier to market.

4. Fabric tear strength is a somewhat overrated value, anyway. After a certain point, design matters a heckuva lot more.

5. Coatings matter more than substrate in the effects of UV damage and in overall fabric strength. Experienced manufacturers also know how to tweak the weave of a fabric to optimize it.

6. Polyester is still going to be more durable over time compared to nylon.

7. Talking about fabrics is nerdy but really interesting.

[Roger Caffin]

Hi Jon
7+

Nylon and polyester are both synthetic fabrics, but nylon production is more expensive, which results in a higher price for the consumer. Nylon also tends to be more durable and weather-resistant, which is why it is more likely to be used in outdoor apparel or gear. Both fabrics are flame retardant, but nylon is stronger, while polyester is more heat-resistant.
https://www.diffen.com/difference/Nylon_vs_Polyester
So maybe mfrs go for poly because of price? It figures.
I like the superior elasticity of nylon in a tent: it can handle more extreme conditions.

Cheers

[Xavier Nitsch]

Hi, I’m Xavier who made some of the above experiment.

Jon told me about this thread, and it is indeed interesting.

I believe i could add some information.

All silpoly on the long term tests come from RSBR.
But you should keep in mind that RSBR sells at least 3 different sil/sil silpoly 20D :
– the “normal” one, which is used on the “long term” experiments. Good fabric in my opinion, though not the best.
– XL silpoly. Tear strength is much lower, puncture strength higher. Less elastic. I suspect a very high amount of PU in the sil/PU mix.
– “eco” recycled silpoly 20D : the best of the 3 in my opinion, highest tear strength and HH (hydrostatic head), slightly heavier (43g/sqm). Also slightly more elastic.

I have built a fair amount of tents with the normal et the eco, and the tear strength and HH remained quite constant over time (a few years).

Silnylons have been bought from extremtextil. They come from Taiwan. On my first experiments (2015-2017) the HH was so-so and not very consistent from one roll to another. Recent experiments (from 2019 and so on) quality increased a lot, with high and consistent HH. The new silpoly 30D is really good, I have ordered a few rolls of it for 2023.

About the figures in the charts, you can see that tear strength sometime seems to increase over time : I do not believe that it is real, it is just due to the inaccuracy of the measures.

About the ripstop, my opinion is close to this thread :
– None to very low increase in tear strength with sil/sil fabrics. Marketing and/or habits driven. I suspect that it could decrease HH over time.
– PU or PeU or Sil/PU : sometime useful (kite fabrics) sometime not (groundsheet with high HH). I have tested side by side a nylon/PU fabric with and without ripstop, and the ripstop one would definetly lose its HH quicker than the non-ripstop one.
– Fabric without coating : I do not have much experience with these, but it seems that the ripstop actually increases tear strength.

Overall I have the feeling that the type and quality of coating is complicated for costumers and usually overlooked, even if it is the most important by far (in my opinion) : “sil/sil”, “sil/PU” do not seem very different for most, but it completely changes the strength and durability of the fabrics.
In the meantime, “ripstop” is straightforward, easy to see and understand.

[Xavier Nitsch]

Sorry i didn’t read Jon’s summary : I totally agree, even if i am not sure about #6 and could discuss #4 depending on the tent and type of use.

[Sam Farrington]

Xavier & all:

The weight of the extra wide silpoly is ~1.75 oz/sq/yd. The ECO is ~1.29 oz/sq/yd.  Those are the seller’s specs, which are not always correct, although RBTR does a better job than most.

My concern comes from what we used to call in the service, “mission creep,” where the desire to succeed leads to too many sacrifices being made to accomplish the mission to the point where the mission fails.

The mission here is to find the best fabric resistant to hail and extreme weather.  And I would add lightest, as this is BPL.  Most are looking for lightest if the number of DCF users despite the price is any guide.  Granted, DCF has shortcomings.

So the concern is that as the fabric weight creeps up to 1.29, 1.33 (ET#72098), and even 1.75 oz/sq/yd, the weight penalty compared to DCF is ever increasing.  And at some point folks will reach into their deep pockets for DCF that while not the lightest, is well under one oz/sq/yd.

And why do we forsake woven fabric for the DCF despite its shortcomings?  Because trimming carry weight greatly improves the enjoyment of backpacking, not to mention much less wear and tear on the bod that can lead to life-long damage.  So it is not surprising that so many on BPL opt for DCF.  And I think we will have to do better with weights of woven fabrics if we want to ‘accomplish the mission.’

[Ron Bell / MLD]

My observations about UL tent fabrics I’ve learned over the last 20yrs.

1: Some equal weight Silnylons and SilPolys are way better than others.

2: Some 20d silnylons are way better than some 30d Silnylons.

3: Some 20d silpolys are stronger than some 20d and even 30d silnylons.

4: Some 20d silnylon stretches way less than some 20d silpoly, even when wet.

5: Some/Most of the 20d silpoly and 20d silnylon availble to DYI’ers though resellers are not as good as the ones used by some tent manufacturers.

6: No one on any forum hardly ever talks about dry stretch on the bias.  That is very important to making curved or large panels function well. Some equal specs fabrics ( 20/30/poly/sil/pu/nylon/etc) stretch on the bias very much different. Some as much as 400% more than others. I think that the dry stretch is far more important than wet stretch, at least for MLD shelter. It’s not part of marketing lit so no one talks about it.  I’ve seen some dry stretch (nylon and poly/ ripstop and non ripstop) that is bad and only get worse when wet. Could this be part of the over generalized myth of wet stretch Silnylon vs SilPoly?  Is there even a lab test standard for this? I don’t know. I only know how I measure.

7: Some Silnylons wet stretch less than other Silpolys.  Some silpolys stretch a LOT less than other silpolys. Same goes for Silnylons.

8: Some runs of the exact same fabric from the same factory perform different. What vintage year was your 20dSilwhatever? Ohhhh- 2017 was a great year!

9: All discussion of tech fabrics exist in a tiny time compressed bubble, but get repeated as current fact for many years.

10:  Labs tests on any tent fabric is only a starting point to understand the end shelter. Design, construction and sealing often is more important to any end function vs the raw material.

11: A DYIer tent fabric choice is almost always great, no matter what happens. Same fabric in a mfgrs tent is not always that great.

12: A higher HH coating can make a fabric weaker due to the higher+longer heat drying process of curing the coating. Do you really want a super high HH…maybe not?

13: Some 10/15d silnylons are stronger with less coating. How little can your marketing shaped perception accept?

14: I finally saw a 20d SilPoly that, on balance for 10+ factors, I think is sort of pretty good. Nope,  I can’t say what it is except that it’s nothing on any list or post from any place anyone here has ever noted.

15. Be careful making generalizations. They can often be generally wrong. I’ve been wrong so many times I now understand the massive amount of what I do not know,  maybe. Probably Ok to disregard all I’ve said above, except #14 and #15.

 

 

 

 

 

 

 

 

[Bruce Tolley]

@ Ron

Thank you for your clear-sightedness and prudence! (and great shelters).

[Jerry Adams]

“Be careful making generalizations. They can often be generally wrong.”

Hmmm… circular logic, I will ponder that..

Wet bias stretch vs dry bias stretch????  I have been coming to realize how important bias stretch is, but now I have to consider whether it’s wet or not, interesting…

[Roger Caffin]

And if Ron is having that many problems with his purchasing power, what hope does the MYOG aspirant have?
Thanks Ron
Cheers

[Geoff Caplan]

Exceptionally useful input from Ron, as always – even if his message is a bit unwelcome. Sometimes reality hurts.

He seems to be confirming Mike Cecot-Scherer’s advice that detailed differences in manufacture and finishing are more important than generalities about nylon vs poly, HH and the like. And that these can vary significantly even from batch to batch.

Manufacturers do have the purchasing power and labs to access better fabrics than us MYOGers, but Mike also points out that he’s seen brands lose their way and settle for inferior products. So even going commercial is no guarantee of quality.

If you are purchasing from a manufacturer your best bet is probably a small, specialist company like MLD or Hilleberg that obsesses over quality and would never compromise for profit or convenience.

For MYOG, I guess we have to rely on communities like this to share our experiences. But then again, most of us aren’t building shelters for the South Coll, so probably any suitable fabric from a reputable source will be good enough, even if it isn’t optimal. So we probably shouldn’t overthink all this stuff!

[Sam Farrington]

” … what hope does the MYOG aspirant have?”

Not too much, Roger.  But don’t think the small businesses have any more luck.  Stephen Seeber suggested it can be a matter of quality control.  Not knowing the ins and outs of the international fabric business, I’ve found that I have to order a yard first and test it, then order the amount needed for the tent, test that to make sure it’s the same or better quality, and only then proceed with the project.  Believe it or not, I’ve been doing that for several years for one project because of the numerous variations like those mentioned by Ron B.  And Dan D informed me that he has a market professional handle the fabric purchases.  I assume that is so the same quality can be maintained for all his tents.

So for both MYOGers and small businesses, quality can be maintained, but it takes a lot of time and is a headache.  But if you are wedded to MYOG tent projects as I am, it is just part of the deal.  Eventually I find the fabric, (not just the product, but the actual swatch of fabric) that is used.

For the current project, victory is in sight; but it’s been a long slog.  Silly me, who thought you could evaluate a certain brand, and when ordering more for a project, the same quality would be provided.  NOT!

This was further complicated by the fact that the design depended on the fabric to hold the pole framework firmly in place; that is, the frame and the fabric function mutually or inter-dependently to keep the tent rigid.  So if the fabric were to lose its shape, the pole framework by itself is not as capable of maintaining the tent shape.  And because storms demand the most from a tent, it was those storms that limited the ability of silnylon fabric to help provide the best wind resistance.

The project also was complicated by the fact that there are different kinds of stretch.  There is elastic stretch, that will return the tent to its taut original shape after each buffet from the the wind.  And there is stretch created when the fabric goes limp and will not return to its original shape until dried out, as does all the silnylon I’ve tested, and there is a basement full of it.  So the advent of silpoly was great news, because it has bias stretch, but is much less affected by moisture.  But the silpoly also has variations and the same due diligence mentioned above is required.

The current project needs the bias stretch also to add considerable space to what otherwise would be a cramped A-Frame.  This is shown in a 2011 thread with a number of visuals, and for those interested, it is at:
https://backpackinglight.com/forums/topic/45631/
Please note that the post was only of a prototype canopy, and that much of the design work remained to be done. I’ve enjoyed all the challenges, though, and hope to come through with a much lighter and stormworthy tent.

[Roger Caffin]

I sympathise. Way back when, I got a sample from Westmark of their silnylon, tested it, and then bought ‘enough’ in two colours – sufficient to last for several projects. It has good HH, lasts well, and handles nicely. So I have been a bit lucky.

Cheers

[jscott]

I recently bought a guitar on line from a reputable luthier. I broke my own rule not to buy a guitar unless I played it first. But the reality is, there are a very limited number of guitars available for sale in my area, even though it’s a metropolis.

My point is, I found a very good guitar at a good price, better than anything available nearby. But even reputable luthiers will make a dud now and then. You have to take your chances. And be able to return the guitar in a reasonable amount of time.

The last posts suggest it’s the same with tent materials.

[Sam Farrington]

jscott,

What a coincidence.  And I follow the same approach.  I’d rather drive all day to check out a guitar than take a chance.  And they can run from the low thousands to many.  Interestingly, my brother is more OK with having them shipped with a brief trial period to return the guitar.  It is a lot of work for him, but he has bought, sold, and returned so many of them that he is adept at the shipping.  So he will order from further away, like Gruhn Guitars in Nashville.  But he is more affluent than I am. You are right, the issues and prices are different, but the approaches to obtaining a fine product are very similar.

[Sam Farrington]

Roger, though you may have been a bit lucky, your tunnel designs, outlined on this and other threads, are probably more suited to silnylon than any other design.  Your discussion of the role of tension running parallel to the tunnel was right on.

[Roger Caffin]

Hi Sam

Well, maybe ‘lucky’, but maybe not quite.
Yes, the design works very well with silnylon, that is for sure.

However, I am not that sure it could not be used to similar advantage with silpoly. Granted there would not be as much stretch available in the fabric, but that may not be so significant. There would still be some stretch, allowing the tunnel to adapt a little to irregularities in the ground. But the main source of tension and stretch in the design lies not in the fabric but in the fairly powerful loops of bungee cord at the downwind corners. Relaxed, the loops are about 150 mm long, but I stretch them out to at least 200 mm, if not closer to 250 mm. A wet-stretch of 20 mm in the silnylon is therefore hardly a problem: the bungee cord keeps the fabric taut. There might be a lesser stretch with wet silpoly, but that does not matter in the slightest.

I also have tension at right angles: the pole sleeves are pulled tight along the poles as well. The combination does keep the fabric taut all over.

Incidentally, can I just add here that while I have bungee cord at the downwind end, I have short loops of 3 – 4 mm nylon cord at the upwind end. Never ever let the upwind end move under the wind. I have a video of what happens with bungee cord at the upwind end: it was not pretty!

It would be a big mistake to think that all this has happened ‘by accident’. It took me several years to develop the design, with 2 or 3 prototypes along the way. They were field-tested of course. I also spent quite a bit of time doing a desk-analysis of the design and working out all the what-ifs (stretch, distortion, etc).

So much for woven fabrics. What about DCF? Yes, I have also spent some time analysing how that would behave, plus Pierre D actually built a double-skin DCF tunnel for use in the snow. I had not been enthusiastic about the idea, and neither was he after a little use. I think he went on to make a silnylon one to replace the DCF one.

Cheers

[Sam Farrington]

Hi Roger,

I corresponded with Pierre when he was making the DCF Tunnel, and am sorry to hear that it did not work out; although with my more recent tests of DCF it comes as no surprise.  By now I must be regarded on BPL as a DCF skeptic.

See no reason why silpoly would not work, but have never tried to make a tunnel out of it, so there may be unanticipated pitfalls.  There usually are.  From some of your photos, I wondered if you had tried making fabric panels with the warp and weft running at 45 degree angles to the poles.

[Roger Caffin]

I wondered if you had tried making fabric panels with the warp and weft running at 45 degree angles to the poles.
For the main panels, definitely not. Bias stretch I do understand. The warp is definitely parallel to the ground.
For the end bells, it is a little more complex, but again the warp is parallel to the ground. That means the zips are on a bias, but the zip tape is more than adequate to hold the shape.

Would there be pitfalls with lower-stretch silpoly? I suspect that one would have to be a bit more careful over balancing the tensions in the main panels where they are sewn to the pole sleeves. The stretch in nylon can handle any slight errors there, but with the lower stretch of polyester it could be tricky. One would not want any loose ripples down the seams or slackness in the sleeves.

I dealt with that even with nylon by making markers along the seams on the patterns, transferring those markers to the fabric, and using lots of pins (in the hem region ONLY) to line things up. The markers were nothing more than thin felt-nib lines: that stuff does work on (stick to) the silicone coating. That is, solvent-based markers, not erasable or water-based ones.

Cheers

[Jon Solomon]

Just last week, the folks at Slingfin published a blogpost about UV damage to tent fabric.
https://www.slingfin.com/blogs/the-beta/uv-and-u-tent-fabrics-and-sun-damage

While this thread was originally focused on fabrics resistant to hail and extreme weather, the discussion did evolve to include consideration of long term exposure, particularly to UV, on fabric performance.

The results of Slingfin’s tests, which make interesting reading on their own, basically corroborate much of what has been said here and especially what Ron’s post mentioned. Unfortunately, the folks at Slingfin did not have a chance to test a sil/sil polyester fabric. But among the fabrics they did test, polyesters often did not perform as well as similar spec’d nylons. Like Ron, they emphasized variation even among fabrics that are from the same factory and suggested that generalization is best avoided.

Color also plays a role in photodegradation. Turns out the best color would be a dark blue. Dark colors in general are more UV resistant because they transform UV rays into heat and blue is the most effective at absorbing long wavelength rays. That color choice may factor in to why Roger’s silnylon tunnel has fared so well. Yet, unlike Roger, I cannot avoid pitching my shelter in the sun for a few hours every day during the summer months when the days in Europe are 16+ hours long.

As the OP, I might say a word about DCF, since that was a fabric choice that I specifically excluded at the beginning of the thread. I have decided for myself that DCF doesn’t fulfill my criteria for safety in the kinds of conditions I am contemplating here. I have used many high end DCF shelters and still have several in my possession but I feel that DCF just isn’t what I’m looking for, for a number of reasons linked to the limitations of the material, principal among which would be the liability of hail punctures even with 0.8 osy CT2E.08, as well as the propensity of the fabric to stretch permanently (i.e., to deform). The price could come way down and I would still feel that way.

The real issue is that really high quality low denier sil/sil fabrics like Slingfin’s 10D 6.6 nylon (which performed amazingly well in their UV exposure tests) are basically unavailable for DIY projects. I’m fortunate to have received a small amount of very high quality Korean 10D sil/sil nylon 6.6 fabric for one of the octagonal mids that I use now but probably wouldn’t have access to that exceptional fabric again were I to want/need to make a new one or tweak the design further (I’m thinking about adding a second door).

Probably the best fabric available to the DIYer now is the 30D diamond ripstop cordura sil/sil nylon 6.6 from Extrem Textil, but it is a rather heavy fabric at 1.47 osy (50gsm). The samples I have of this fabric feel like the coating and finishing is of a very high quality. Most people on BPL would prefer a lighter fabric, I’m sure. Compared to a 20D sil/sil nylon like ET’s 20D silnylon at 36 gsm, the weight increase is substantial. Yet, the 30D is superior in every other way: less stretch when dry and wet, better UV resistance, stronger tensile strength, and probably more durable coatings, I’d wager.

The 30D silpoly from ET may thus be the best compromise at 1.33 osy (45 gsm). It would be interesting to see these new fabrics from Extrem Textil tested for the effects of photodegradation over time.

[Jerry Adams]

I don’t normally leave my tent out in the sun so UV damage isn’t that important

I’ll set up tent in late afternoon and take it down in the morning

and I pitch it mostly in the shade of trees

if I left my tent at a basecamp all summer, in the sun, it would be a different story

[jscott]

Killer hail is the least of my worries. And I’ve been in a lot of hailstorms, typical of the Sierra. I’m not going to buy a tent based on the outlier chance of a storm with golf ball sized hail happening. (exaggerating for effect.) Again, I’ve been exposed at altitude to a many wicked hail storms. I’ve never thought twice about it, until this article came along.

How likely is it that an unprecedented hail storm occurs with no prior warning (conditions suggest one should get below tree line)?

Of course I’m speaking of my familiar three season conditions. For others, this may be more of an issue. BUT: even the article suggests that this was a highly unusual storm. Spend enough time outdoors and we’ll see everything. If I prepared for everything, I’d never get out of my house.

[Roger Caffin]

an unprecedented hail storm occurs with no prior warning
We get them here on the East Coast of Australia.
Bright fine sunny cloud-free day up the mountains, so we went off to look at a nearby hut, an hour away. Still bright fine sunny when we got there.
Half-way home and a hailstorm hit us – hard. As I said to Sue later on: comes of going any distance without a poncho!

Cheers

[Sam Farrington]

Jon S,

Thank you for starting this thread.  It has been very helpful compared with many on this subject.

Longtime members of BPL will not be surprised that I am still harvesting fabrics from tarps.  I’ve found that it is the only way to obtain the lightest weight and best quality, compared with ordering from the fabric market.

Currently, the focus is on silpolys for the reasons earlier stated, and I’ve found one fabric that meets or exceeds expectations and weighs under 1.1 oz/sq/yd, finished; as I  wanted to get the weight down as close as possible to an ounce finished weight.  And expect to test another fabric next week that looks promising.

While the focus here may be on heavier fabrics, I have never retired a tent for damage to the canopy from severe weather, or any other cause; rather, the reasons have been either obsolescence or wear and tear after many years of service.  The prices of the tarps are competitive to DCF when you consider the tent weight, life, and absence of failure in the field.  And recall that those on the Skurka trip, discussed on another current thread, have stated that none of the hail damage happened with woven fabric canopies.  Finally, it also helps to design for a smaller canopy with a narrow fly that can readily be replaced if it should fail.

The approach may be different for a tent floor that is more subject to abrasion, especially without the use of ground cloths.  So am looking at finished weights of silnylon from Warmlite, Lightheart Gear (Korean) and some others to see what weight penalties would be compared to best quality one oz silpoly.  But agree with jscott about not preparing for everything.  Such a tent would be so heavy, few would want to carry it.  While a spacious solo tent under 28 oz with enough space for meals, gear storage and a small dog or two at a reasonable price should for many be well worth a best quality woven silpoly fabric vs DCF.  Will post on the MYOG forum when the project is completed.

[Jon Solomon]

This is occurring here in Western Europe with increasing  regularity:

The relatively low altitude at which this photo from earlier this year was taken is almost certainly a factor in the size of the hailstone, but there were reports two years ago of similarly sized stones in the Italian Alps, at higher altitude. I’ve personally encountered stones about 1/3 to 1/2 this size in the Pyrenees. Of course, there’s no warning.

You may not want/need to plan for this contingency, but I have decided that I do. I camp regularly above tree line with no cover in sight and at 60 yrs of age just don’t have the seemingly unlimited reserve of power that I used to enjoy that would sustain me hiking at night through gale conditions to find shelter from the storm. Now, I could modify my style of backpacking but I’m not ready to do that, yet.

Getting a good night’s sleep is also more important to me now than before. I’ve mentioned this in other threads so forgive the repetition but I value shelters that don’t just meet the minimum requirements of staying more or less erect during severe weather but remain relatively stable and don’t flap and flop all over the place in very strong winds. I’ve had several MLD Duomids and now have an LG Khufu and despite the fact that they stood stout in horrendous winds (I had a Duomid in a typhoon), the noise was so loud that sleep was impossible — even with wax earplugs (i.e., earplugs that provide a good seal).

Sam’s strategy of buying large flat tarps from manufacturers like Hilleberg or LG to harvest the material is a good way to obtain fabrics otherwise unavailable to the MYOGer. The huge price markup is a pity. It also isn’t always obvious that you can get the fabric you really want/need. For instance, while you could harvest fabric from a Hilleberg or Locus Gear silnylon tarp (at an exorbitant markup), the fabrics they are using for their tarps are both 30D sil/sil nylons that probably don’t offer significant advantages over the 30D silnylon from ExtremTextil. The silnylon used by Lightheart Gear is also 30D (the silpoly is 20D but they don’t normally use that for their shelters. Sam: how do you know that Lightheart Gear source their 30D silnylon from Korea? Never saw that mentioned before. Interesting!). Etc., etc. The 10D silnylon used by Gossamer Gear for their tarps isn’t pure sil/sil. Vango specifies a PU/sil coating for their Korean 7D and 15D fabrics — presumably so they can factory tape the seams. The really awesome 10D sil/sil nylons used by Slingfin, The Free Spirits,  etc., aren’t available in a flat tarp from any manufacturer, as far as I know (please correct me; I’d love to have the information/be reminded).

The 30D silpoly from ET that weighs the same as some 20D silnylons might be the best option right now but as I said before, it would be great to see this fabric subjected to the same testing (and the superlative but heavier 30D silnylon from ET, too).

YMMV.

[Jon Solomon]

Here are some photos of my octagonal mid made to my specs by Xavier with Korean 10D sil/sil nylon 6.6, total weight 373g:




and one pic of the version made with ET’s 30D silpoly (slightly different design from the 10D silnylon version above):

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