Sil-nylon Misting

[Matthew Swierkowski]

In the spirit of what Ron Bell said on another thread where things got way off topic into the realm of sil-nylon misting, I thought I would start this thread. I’d like to get a spirited discussion going on this whole misting issue. I know this is been discussed before, but let’s get everyone’s opinion condensed into this thread.

My opinion is that the misting issue is real, but it is also way overblown. I think the majority of misting reports are really just condensation on the under side of the tent or tarp being knocked off by wind or rain. That being said I can confirm that I have been misted on under sil-nylon (and in one case actually rained on).

I personally have several sil items. I have 3 tents (Squall, Double Rainbow, Akto) and a poncho/tarp. My experience with these items is purely subjective, so I wanted to disclose that before I go on. I will also note that I am actually an engineer, but I haven’t had the interest to go to the “nerdery” to perform any actual tests and record data. I don’t know that it would be that easy to get concrete results anyway as there is a wide variation in the quality of different sil fabrics, and the amount of use likely has a significant affect on the fabric.

To me sil-nylon is an awesome fabric. It’s light, durable, fairly inexpensive and basically waterproof for most applications. The short comings of it are that it stretches and can end up eventually leaking (whether it just be minimal misting in extremely heavy rain, or flat out leaking because the silicone is just not well applied or has worn off). I haven’t really seen another fabric that has all these characteristics, so I have come to a point where I just live with the sil-nylon shortcomings.

As I have documented in other threads I really think the issue with sil is just the fact that it needs to be periodically treated to remain waterproof. Most people are going to balk at that because they don’t want to have to do any extra work, but it is what it is. There’s going to be tradeoffs for anything. I mean you change the oil in your car and don’t complain about that right?

Anyway, so far I have tried silicone sealant diluted in mineral spirits painted on, and the Astko spray on silicone sealant. The method of painting on the silicone seems to work well from my experiment with my Squall where I did the under side of the canopy and the floor on the inside. Although I need to get some decent testing done on it, the spray on stuff seems to work well too. I applied it to my poncho/tarp, which was basically acting like a coffee filter…water was going right through it. One application of the Astko stuff, and water doesn’t leak through it anymore (checked this by making a “cup” out of part of the poncho and filling it up with water…I had to actually put some pressure on the water to get any to come through).

So, in conclusion I think the misting is an issue, but I think the answer is to just maintain the fabric. I haven’t done enough “testing” yet to make any suggestions, but perhaps treating it once a year with the Aksto stuff would suffice. The periodicity of treatment is obviously going to vary based on the item, how much it’s used, what quality of sil was used to construct it, and so on.

[W I S N E R !]

Given condensation typically occurs in the same wet weather that causes "misting", how exactly does one CONFIRM that the spray occurring under a sil shelter is in fact misting and not condensation being knocked off?

I've experienced some of this to a minor degree under a sil tarp (Oware Cattarp 1.1) but it seems to me that it's simply condensation. To test waterproofing I once hung this tarp from a tree and poured a few gallons of water into it (I mainly wanted to test my seam sealing). It sat for over a day with no visible sign of leakage through the other side.

So does hard rain really hit hard enough to force itself through the pores?

From personal experience, I just don't really buy the "misting" idea.

[Miguel Arboleda]

Personally, I'm done trying to convince anyone that my latest experience (last autumn) with silnylon was much more than just light sprays of condensation being knocked off. As I've stated, I've experienced both the misting and the full-on "raining in through the tent fabric". It could very well be the age of the fabric and the need for a new coating. That I don't know. The shelters were not old. If no one wants to believe what I and my wife experienced, well, it's no shirt of my back. Everyone will experience what they experience. If I do happen to be right, those doubters who experience their first deluge with rain flooding their tent, well, I'm sure you'll have a delightful time. Enjoy!

I'm wondering if water itself dilutes the silicone on the fabric.

[Richard D.]

The true cause of the misting effect can be determined by comparing silnylon to spinnaker and cuben in identical conditions. Since cuben is a laminated plastic and 100% waterproof, if a cuben tarp allows "misting," too, then misting on both cuben and silnylon is from condensation on the bottom of the tarp rather than water being forced through. If, however, misting with cuben is not observed, than it is probably due to incomplete waterproofness of silnylon.

People with lots of experience camping in extended rain under shelters of different types might be able to compare different fabric performance. I'm interested in their observations. I personally don't have enough experience with heavy rains.

[Mark Verber]

I am with Matthew. I think sil-nylon is a wonderful material when factoring in it's cost and performance characteristics. I have experienced misting so I believe it exists. I also think misting is typically overblown… I have never personally experienced misting that was more than annoying… though I can believe in very rare situations it could be more serious. People should keep in mind that sil-nylon has a large variance in exactly what process is used and the weight and weave of the nylon. So there are conditions that one type of sil-nylon won't mist, and another would.

I have used sil-nylon shelters for a number of years. While it is rare, I have experienced misted. How do I know that it's misting and not condensation? Because I wiped the inside of the tarp to try and get the condensation off the walls. The droplets seem to aim for my face and were keeping me up. I "knew" that when I removed the condensation the "mist" would stop long enough for me to fall asleep sicne it would take a bit of time for the condensation to reform. I wasn't worried about the condensation being knocked off as I slept since I had never had some much "mist" that it impacted my quilts performance. (e.g. it was just an annoyance). The wipe-down didn't stop the misting on the side of the tarp that was taking the major force of the wind but the other side did stop "misting". The more sheltered side of the tarp took awhile to reaccumulate enough condensation to start to "misting" again.

Pouring water isn't effective way to simulate field conditions. First, you need to dump the bucket from 20ft up so the water has time to reach terminal velocity. Beyond that you need the water to be accelerated by the wind. If you want to see misting hit the tarp with a concentrated nozzle on a hose.

I don't have a calibrated hose. My hose / jet nozzle runs at a higher pressure than I have seen in the field since the misting it produces through my sil-nylon shelters is more than I have ever seen in the field. I believe all the sil-nylon I have given the hose test misted quite badly. My memory is that the GoLite Hex was a bit less than most of the others. The spinakker used in the first generation "the one" also misted slightly with the hose though I never saw it mist in the field. A prototype bpl/oware cuben shelter didn't mist, nor did the earlier version of Spintex used by MLD (they claim their 2009 is even better)

–Mark

[Jim Colten]

OK … I've long been a skeptic of the silnylon misting (more recently leaking) phenomenon. Well not so much a skeptic as just not worrying about it … a minor inconvenience.

But when longtime forum posters who routinely provide insightful and thoughtful accounts of their own experience report things that I have not observed I have to react by asking myself what might be different in their case vs mine. In this case I suspect the difference might be that I have not purchased silnylon in about three years (haven't used up what I have).

The difference is largely that there is no such thing as "silnylon" in the sense of it being reliably manufactured to a common spec. The bulk of silnylon is manufactured for purposes where being waterproof is unimportant. Ten years or so ago it just so happened that it was waterproof enough to meet our needs and it was the bees knees of shelter fabrics for our crowd … a fortunate accident!

More recent reports tell a different story. So what's a guy or gal gonna do? Well there are folks like Ayce at Thru-Hiker, Ron at MLD and (I think) Grant at Gossamergear who have business needs for fabrics that meet our needs and who put in the effort required to work with textile manufacturers to develop new products. The result has been Momentum, Dyneema X Gridstop and SpinnTex EXP. Past track record on these efforts leads me to expect that Shield ™ Silnylon will be just as suitable as those predecessors are.

[Roger Caffin]

Hi Jim

> I have not purchased silnylon in about three years (haven't used up what I have).
Yeah, this can be significant. Silnylon does vary, and if you got some good stuff hang onto it! If you have any of the old 'wet-look' stuff, treasure it!

> The bulk of silnylon is manufactured for purposes where being waterproof is unimportant.
Exactly. Exactly.

Someone else asked whether water can affect silnylon. I believe the answer is yes: the silicone polymer is marginally soluble in water. This means that the coating will slowly wear off. However, before anyone immediately blames this for their problems, be aware that it might take several years of intensive use before the effect is noticeable. For most people it will never happen.

Also, my experience is that the silicone polymer is slightly porous, compared to a PU coating. The effect here is extremely small, but I have seen it when pressure testing fabric with silicone on one side and PU on the other. It wasn't visible until about 50 kPa or higher. I don't think the porosity would ever be significant in the field, but it is worth noting that the different polymers do have different behaviours. Fair enough.

Cheers

[W I S N E R !]

So, with the exception of cuben, is 1.9 oz. PU coated the lightest that can be declared "mist free" or waterproof?

[David Ure]

Hilleberg Kerlon 1200 is 1.47 and rated to 3000mm – fully, completely waterproof.

[Jim Colten]

OK, I've bit my tongue long enough on this … he-he

Regarding "waterproof": if (to list a few) the Vajont, South Fork, St. Francis, Baldwin Hills, Dale Dike and Llyn Eigiau Dams weren't "waterproof" how'd anything I'd be willing to carry on my back qualify?

Not intending to rip anyone here … just trying to poke a little fun at our (myself included) tendency to search for that perfect piece of gear.

[Mary D]

I have never experienced misting in any of my silnylon tents either in Rocky Mountain cloudbursts or when testing them after seam-sealing under a garden hose with a fairly high-pressure nozzle (what you'd wash the car with).

However, the deluge and/or hose treatment never lasted longer than 20-30 minutes. I've of course been in lesser steady rains, also with no problem. I agree that it's difficult to tell the difference between leakage and falling condensation. (If my dog is doing his Labrador tail-wag routine in the tent at the time, though, I'm sure that what is falling is condensation!) The exception was when I discovered that I had skipped a small spot when seam-sealing the horizontal seam on a SMD Lunar Solo–that was an obvious leak!

Miguel, I remember reading about your misting/leaking experience. Wasn't that a full-fledged typhoon, or at least the rain-filled remains of one? I strongly suspect that most tent and fabric makers never expected their tents to endure those conditions! In those circumstances, I most certainly do believe that you had a problem, and I'm glad that you didn't float away!

There's always the possibility of a bad batch of silnylon, too. I would want to contact the manufacturer if leakage through the fabric happened to me. It's not supposed to happen under normal conditions. Thorough testing with a hose is, IMHO, a good idea (as I realized after the Lunar Solo incident).

Conclusion: Misting has not happened to me with 3 different silnylon tents, nor with my silnylon rain suit (one of the last made by Brawny Gear). But I don't discount that it could happen in extreme conditions (Miguel's typhoon) or with a bad silnylon batch. After all, my "sample size" is far too small to be meaningful!

Maybe we should just limit this thread to poll-type responses stating whether or not we've experienced misting or leakage that didn't appear to be condensation or a seam-sealing error, rather than pontificating–now that I've already pontificated for several paragraphs! :-)

[Roger Caffin]

Some additional information.

Many people have talked about the pressure that heavy rain puts on a tent fabric. But who has measured it? How big is the pressure?

I have spent a fair bit of time doing Suter tests (water pressure tests) on a whole range of fabrics. Even at 15 kPa the bulge in a small bit of fabric is serious, and I am talking about a circle of under 2" diameter. The bulge at 70 kPa is alarming! If I compare that sort of fabric distortion with what I see under gale-force storms, I have to say that the storm pressures are but a wee fraction of what I get when testing. rarely more than a few kPa.

However, pitch your tent on hard ground and kneel on the groundsheet. Now you are seeing some significant pressure, and if the ground is really wet you may also get a slightly damp knee. That's why groundsheets are often specified to a higher pressure rating, and why I never kneel directly on my groundsheets. I always have some foam there.

If you have a tent pole inside the tent holding the fabric up in a storm, it is possible that the fabric in contact with the pole may be getting a significant pressure. You might, maybe, get some leakage right AT the pole. (My poles are outside the tent and the seams are heavily reinforced and sealed.)

Hope this helps
Cheers

[Miguel Arboleda]

Hi Mary,

Interestingly enough, the time last year when it rained in the shelter was not a typhoon, just one of the regular, deluge rains of Japan. There was very little wind that night. The rain, and I mean "RAIN", came straight down, for eight hours. On the other hand, the few times that I've pitched a shelter in a typhoon (one time on purpose, with a homemade silnylon teepee in a park near my home, and another time way above treeline in a TarpTent Rainbow that had not been seam sealed, to name two times) I've only experienced the condensation being knocked off the fabric. The Rainbow experience taught me the importance of seam sealing… there was very little misting, but the seams leaked like sieves. The homemade teepee had no problems whatsoever, though I was using factory seconds silnylon from Noah Lamport. And another time, with a newly purchased TarpTent Squall 2 (I had been using the Squall 1 for quite some time by then) I got back from a day hike with my shelter pitched at a base camp just as a huge storm hit and my wife and I lay reading books while the rain pummeled the shelter. We didn't even experience light misting, though the fabric had condensation on it. This was the same shelter that four years later got rained in.

Japan gets tons of very hard rain, rain that I've never experienced anywhere I've lived or traveled in North America (Massachusetts, Maine, Oregon, Washington, New York, North and South California, South Carolina, British Columbia, Montreal, Nova Scotia, though I suspect South Carolina gets similar weather at times) or most of Europe (though the Alps sure had some wild weather!) Even Scotland and Norway, though very very wet and cold, didn't have that kind of rain. In the summer of 2008 it deluged here everyday, 24 hours for two months straight. Never had I seen so much lightning in my life! (albeit it was a freak summer, too)

[Miguel Arboleda]

The two silnylon fabrics that I have absolute confidence in are, as David mentioned above, Kerlon 1500 (my 1999 model of the Akto, which is heavier than the present model) and Kerlon 1200 (my 2007 version of the Soulo). They have condensation get knocked off, but nothing else. The raining through the fabric has never once even come close to happening. The fabric feels much more robust than the "regular" silnylon you get.

[Matthew Swierkowski]

I failed to mention my own personal experience with misting. It has happened to me twice that I know of. The first incident was in my Squall in a biblical deluge that lasted all night. I know that misting was occurring because as Mark Verber detailed in his post I was wiping the inside of the tent down, and droplets were coming through the fabric immediately after it was wiped down…to soon for it to be condensation. It wasn't a big deal, but I had a hard time getting to sleep because it was misting on my face. Not very comfortable.

The other incident occured on my last trip out with my poncho. I was in an all day rain wearing the poncho and slowly getting wet under it. At lunch time my buddy pitched his sil ID tarp leaving some extra guyline available along the ridge for me to throw poncho over. So we basically had his tarp and my poncho pitched in one large continuous shelter. I was sitting under my poncho getting wet. I didn't understand what was going on until I looked at the ID tarp, and there was no water on the under side of it. In contrast there were large droplets coming through my poncho. That explains why I had been getting wet earlier.

As for my other shelters I have only been in heavy rains (and sleet) in my Akto, and it has never misted that I know of. That's consistent with what others have said about the Hilleberg Kerlon fabric. It seems to be a much more robust type of sil.

[Brad Groves]

You know, every time I see this thread I think "I've never gotten wet in a double-wall tent." (Double-skin, if you prefer.)

Every single-wall tent or tarp shelter I've used I've experienced some kind of wetness problem. (Edit: not every night, but many) Usually condensation build-up. The misting I've experienced has definitely been condensation getting knocked off. The leaking of silnylon I've experienced I observed as "weeping," big droplets of water seeping through the fabric.

Regardless, I got tired of getting wet, or having to wipe down walls, etc (even get condensation under a tarp pitched to maximize airflow)… so I made the switch to double-skin and have been dry ever since. To me, that's kind of the point of a shelter (that, and keeping the bugs off).

Of course, you do still get some condensation on the fly of a double-wall tent. But I find that even just noseeum mesh prevents any "misting" that I'd otherwise experience.

My 2 cents…

[Sam Farrington]

Matthew,
Since it sounds like you are looking for feedback both old and new from "everyone," and at the risk of being once again lambasted, I will add this:
All coated fabrics will leak if enough pressure is applied, and the poorer fabrics with weak points, pinholes or poor coatings will leak in a long deluge.
If any coated fabic is balled around a few grams of water and the ball is compressed, at some point you will see droplets coming through. As has been pointed out to me before on earlier such posts, the problem is: How do you accurately measure and compare the degree of water resistance in different fabrics. I do it by noting whether I have to really push to get the droplets, or whether they come through easily with slight pressure. To my surprise, there have been wide variations, with silnylon from some suppliers performing quite well, and others not. So it is not "scientific," but it allows me to select better material for tentmaking.
But I would not do this with a tent already made because pressure tests of the fabric on the tent will probably do some damage. Ditto if you use a pressure hose over the fabric stretched over a jar or the like. So I think many of you are right about purchasing silnylon gear from the most reputable manufacturers, even kerlon if you accept the greater weight.
For tentmaking, it is easier, because a scrap of fabric may be used to test before the material is incorporated into the tent. Over time, I have found that some suppliers provide consistently better fabric, but I have learned to test every order.
And there is also the matter of whether the fabric is stretched at some point in the design. I think the approach to this issue is better design, and good reinforcement of the fabric at unavoidable pressure points. I also search with a strong light for pin holes and imperfections that are not readily apparent, which is something you can also do with a tent already made.
Until one of the BPL gurus starts scientifically testing products and fabrics from different suppliers, I think this is about the best we can do. Or maybe a better fabric will come along with less flammability and more consistent water resistance. Correspondence with folks at some of major manufacturers tells me not to hold my breath.
Sam Farrington, Chocorua NH

[Roger Caffin]

Hi Samuel

You could look up 'Suter test' (eg at http://www.worldoftest.com/suter.htm) to see a measurable method. I use something like this myself.

I would love to chat with you about fabrics anyhow. Would you be willing to contact me at [email protected] maybe?

Cheers

[Ross P Hemphill]

I recall a very wet night in my Hex due to misting. This was during a thunderstorm in a fairly exposed spot, and boy were we glad to be able to dry out the next day. One thing I think is of note here is that the tent is made with silnylon heavier than our typical 1.3-1.4oz/sq yd (~44-48gsm) stuff. The tent had been used ~30-40 nights at that point, but not experienced a lot of weather, so coating/impregnation degradation wasn't/shouldn't have been an issue. That's the only time I recall having experienced misting, but it's also the only time I recall having it out in rain that hard.

I don't recall being misted on under my tiny Hennessy tarp. (It's hard enough to stay dry under that thing as-is.) Of course, it tends to be under trees, so that's one reason it hasn't seen particularly high-pressure rain.

I put "misting" in quotes above because misting is typically the manifestation people experience, but sometimes it's much worse than that…

[JM Addleman]

When I was reading up on this topic, I came across this thread. At the bottom of the first page, a member Jim Wood mentions testing silnylon to 1-2 psi with a homemade hydrostatic head, with notable deterioration in performance of used fabric.

Unfortunately, it doesn't seem he was able to test the Jardine 'proprietary' fabric.

[Brett Rasmussen]

I've experienced misting once. It was in a tarptent that was fairly new. Not that I think it is anything particular to tarptents. At the time I had never heard of silnylon misting. I initially thought it was condensation being splashed off the tent. Because it was excessive I wanted to confirm my theory so I wiped a section of the fabric and held my hand next to it. Sure enough it continued to mist just as before. In my case it was just an annoyance. I could feel it on my face and there was a light layer of small droplets of the sleeping bags, but the DWR handled it fine. Still I like trying to improve on things and I have painted diluted silicone to much of my gear.

My misting experience happened in a severe storm during a multi day backpacking trip at Yellow River Iowa. The next day a ranger showed up to see if we were alright. Apparently a tornado had passed by. With as hard as the rain and wind were, the lightning and thunder were the most concerning. The thunder was enough to hurt the ears and for several hours the sky was light about 4 out of every 5 seconds with one or multiple lightning strikes. Not the kind of weather I would intentionally camp in. The strange thing was that while my wife and I were terrified, our 18 month old daughter who wakes from the tiniest sound at home, slept through the whole thing.

[Matthew Swierkowski]

I see the sil misting thread was resurrected. I had forgotten about it. I looked at my original post, and I have an update on the Aksto spray on silicone. It worked ok. Now I have to preface this with I think the coating on my sil poncho was heavily degraded, so it might work really well on a better coated sil item that is just slightly leaking. At any rate, it still leaked a little primarily in the hood after multiple coatings of the Aksto spray. So I went ahead and did the paint on method with a 4:1 ratio. That seems to have resolved the problem for now as I got no leakage through it on a recent trip.

[David Olsen]

"So, with the exception of cuben, is 1.9 oz. PU coated the lightest that can be declared "mist free" or waterproof?"

Craig-
There are more variations of PU coatings than silnylon.
I am making some inexpensive tarps for a large outdoor school
which are 70d ripstop nylon with a .25 oz urethane coat
similar to the weight of the silicone coating on silnylon.
Rough tests show it to be similar in water resistance too.
They have functioned fine for their purposes.

I always use a solvent based urethane, as the water based,
while cheaper and supposedly more green (depends on the
manufacturer whether the solvent fumes are recaptured or
not) they dissolve much more quickly and the item needs
replacing sooner.

For example, some of the first stuffsacks I made had a poor
quality PU coating and the end users found after just one or
two trips through the washing machine the coating was peeling off.

On the other hand, I made a mattress cover for my little boy
before he was able to hold it all night. Made it out of a
70d taffeta with a 1 oz solvent coat PU. After literally
100's of washings it is still as good as new.

To get increased resistance to water under pressure, you
can do a couple of things.

Increase the coating thickness.
Increase the steepness of the shelter pitch
to reduce force from the rain.

Advantages to silicone coatings are that most are coated
both sides which decreases water absorbtion by the fabric,
and it also increases the tear strength of the fabric.
Most silnylons are also made for hot air balloons and
parachutes and as such use a stronger version of nylon
called type 66. The tear strength of 1.3 oz silicone
coated nylon exceeds that of 1.9 or 2.2 oz urethane
coated nylons.

[Trevor Greenwood]

I had been thinking about making either a tarp or "tarptent" out of silnylon but all this talk is giving me some second thoughts. For the guys that have gone the MYOG route what is the best value per dollar performance wise that you've found for suppliers of silnylon?

Currently I'm using a 2 man double wall tent that is nearly nuclear war proof but weighs close to 4lbs. I tend to hike at high elevations where the rain at night is cold and miserable so I don't care for the idea of getting soaked by a leaky, misty tarp. I also hate making mistakes and wasting time and money on something that will not perform very well.

So any thoughts on good sil suppliers would be appreciated.

-T

[John Drollette]

"For the guys that have gone the MYOG route what is the best value per dollar performance wise that you've found for suppliers of silnylon?"

For my first MYOG silnylon tarp in 1999 I got the nylon from Quest Outfitters. IIRC, the materials were about $90 shipped. (Large tarp with awnings). After about 250 nights, it was noticably less "silicony" and was misting. It is structurally sound but semi-retired at this point, pending me figuring out a way to re-silicone it.

For my second, very similar MYOG tarp in 2006, I got the tarp kit that Ray Jardine sells. Part of his site is down right now, but IIRC his kit was less expensive (huge guess: around $70?) and I really liked the included guylines and hardware. If his site goes back up as scheduled, my wife and I were just talking that we should buy another kit while we can, since our PCT thru this summer will probably finish off the silicone on this tarp. (odometer: 180 nights and counting)

However, this second tarp seems to be much more "silicony" than the first one was at the same age. Admittedly, the first one got HAMMERED many times in huge rainstorms on a London-Istanbul bike tour. The second one got snowed on several times on the CDT, but not as violently. Another difference is that I use a sil-nylon stuff sack for this second one which perhaps preserves the performance vs. stuffing it randomly and vigorously into my pack.

[Author]

Posts