“Misting” Silnylon!

"Personally, I fail to see what all the hullabaloo is about a little misting or condensation."

Well, if you're lying in a hammock with the tarp just above your head and the misting keeps spraying your face for over three hours, it gets fairly annoying. Not dangerous or anything, just real tough to fall asleep. :-)

I was once stuck in a tent for two days under rain that we could only describe as someone literally taking buckets of water and pouring them over our tent. It was ridiculous in the most ludicrous of ways. My tent didn't leak much, just a little around the windows. However, I can attest to the fact that when the water droplets hit the tent fly you could in fact SEE a pit form. There's a lot of force in the little droplets and I wouldn't be surprised if they could in fact make it through lighter fabrics.

Also, I believe the 1000mm hydraulic head figure stated earlier is really quite conservative. One meter of hydraulic head is not that much, I'm quite certain you could get many times that pressure in really bad downpours.

I'll add to Jim Woods comments on using roaster bags. I don't know what brand I have been using but I have used them for several years for sleeping bags and though I push them in tight I have never had a seam failure. I usually develop a couple of small holes just from use after 20-30 stuffs. I roll my sleeping bags tight, use 2 short pieces of parachute cord as ties, push it sideways into the roaster bag, fold over the excess and put that side down. I believe it would keep my bags dry in anything except being submerged.

Jim,

Thanks for your insights. As a tarptent owner here in Washington, I'm all for maximizing the waterproofness of the silnylon that's over my head. You mentioned – both in the original post excerpt and in your followup post – that the coating should be applied to the underside of the canopy, but then you state that the increased slippery-ness is a benefit to shedding snow. Am I missing something? The comment makes sense if the additional coating reduces the silnylon slippery-ness (so it should only be applied on the underside), but I'm hoping you can clarify.

Dave,
He is referring to the increased slipprey-ness of silnylon vs other fabrics or uncoated silnylon. In other words, leave the very slick surface that is facing up and out uncoated.

Yes Dave, the siliconised coating makes the silnylon very tacky, so better on the inside. It is the same reason many people coat their floor with this stuff, to stop them from sliding around on the silnylon floor.

Well, if you're lying in a hammock with the tarp just above your head and the misting keeps spraying your face for over three hours, it gets fairly annoying. Not dangerous or anything, just real tough to fall asleep. :-)

Each person is different, of course, but it certainly doesn't bother me to have some spray blown in under the sides of my tarp and that has definitely happened to me many times, though I've yet to experience the misting problem. (Incidentally, I'm pretty sure my tarp silnylon is from Ray Jardine. I'm not necessarily recommending Jardine as a good source of silnylon, given how every batch of that stuff seems different and given how much junk I've run into over the year. However, it does appear that the batch or supplier he used to supply me was a good one and maybe he is still using that batch or supplier.) Also, bivy sacks, if used alone, will normally let in far more liquid moisture than even a bad tarp or tent, and that hasn't stopped people from using bivy sacks. So while I'm all for publicizing the facts that silnylon can leak under hydrostatic pressure and that silnylon differs tremendously in quality, I still think the original complaint is somewhat hysterical.

As we are just getting our first silnylon tent after a couple of months or research and reading everything we could find, this thread has us concerned on how to deal with that ultimate hard rain. On my first reading I dismissed Rog's idea of a space blanket or heat sheet as a poor idea. But as I re read everthing I gave it another thought. We will be taking an emergency blanket anyway and the larger Heat Sheet is 5'x8', 3.5 oz. of low density polyethylene–not mylar which can tear more easily. I found these micro tarp holders http://shelter-systems.com/gripclips/products.html which weight only .085 oz. which I think could easily be used to anchor the corners of the Heat Sheet to the 4 corners of our new Double Rainbow.
Comments and opinions from other experienced hikers would be appreciated.

Given the UV degradation ultralite materials suffer, leaving a space blanket over your fly when you are leaving your tent up while you go day-hiking in blazing sunshine isn't a bad plan either. They are so much cheaper than replacement flys…

I haven't found mylar to be all that fragile either. For sure you have to look after it's integrity or it'll rip from the weak point, but if you use the ping-pong ball and rubber band trick for fastening points, they are surprisingly long lived. I used one until most of the aluminising had gone off one side…

Mike just emailed me to say my spinnshelter is on it's way. Can't wait! Spinaker seems to be in short supply at the moment.

Roger is absolutely right here.
I once slung a very cheap plastic poncho over a tent with a hole in the roof during 4 days of on/off rain and wind, and it stuck there and did a perfect job.
Worked a treat: a simple solution to a problem which you would have to class as rare.

Also, I wonder how dilute it is possible to go with silicone and spirits, to stop any possible misting, as well as helping to waterproof the floor?
I suspect we could go considerably more dilute but have no evidence. Anyone tried it?

I am looking at this Alps Mountaineering freestanding tent that I have with its lightweight PU/plastic fly and I am wondering why some of the current lighter setups are not made out of this since it would probably only add 2-3 ounces over the total weight and it would be waterproof in a torrential downpour. Most of the venting now seems to come from noseeum netting anyways. Or am I missing something?

Hi Brett. Actually a few of the newer tents out there (Big Agnes and MSR come to mind) are made with a combination of silicon and PU, silicon on the outside and PU on the inside. I take it the companies have done this because of the misting problem. I had no idea about this development until I started my search for a 2-person tent recently. Sounds like a good solution to the problem.

Miguel, a combination of silicon and PU may actually be less waterproof then standard silnylon.

See the post by David Olsen ( oware ) in this thread:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=3253

So while I'm all for publicizing the facts that silnylon can leak under hydrostatic pressure and that silnylon differs tremendously in quality, I still think the original complaint is somewhat hysterical.

Hmm, hysterical? I guess you had to be there. Over the 38 years I've been out camping around the world I've certainly experienced a lot of different conditions and been through some crazy weather. For the past eleven years I've been exclusively practicing UL methods and have tried everything except cuben tarps (only because it is too expensive for me). I even survived two major typhoons in an old TNF Tadpole (not something I would have willingly gotten myself into). And I've experienced the usual misting numerous times in my two TarpTent Squalls (original and number 2) and my Rainbow. So I think when I related my little experience last week I might just have had the teensiest idea of what I was talking about.

As I said in my original post it was truly wild rain. Think "you can't see more than three meters in front of you". How many of you have experienced that? For 10 hours straight? I haven't even experienced that in most of the typhoons I've seen. And as I've insisted, it wasn't just misting through. Why other contributers keep gainsaying or doubting what I stated I really can't understand. I was sitting right there watching big fat raindrops pound right through the material. My wife and I sat with our rain jackets on wiping up the floor and the surface of all our equipment, but couldn't get any of it dry enough fast enough. I've never needed to do that before in the several hundreds of times I've camped when the shelter was intact. Not even with my early experiences of Japanese rainy season camping in cotton A-frame tents when I was a boy (and if you've experienced those in a prolonged rain you know what I am talking about).

Please, I'm not just some newcomer to all this. I've been around and I'm not prone to getting hysterical about bad conditions. My wife and I were laughing about all of the rain as it happened (I mean it wasn't as if I was going to die). But that doesn't mean I want to go through it again. I wrote the original post so as to give people an idea about what could go wrong with silnylon in severe conditions. If you don't believe my observations then simply ignore them. But please refrain from calling me "hysterical". I am nothing of the sort.

Miguel, a combination of silicon and PU may actually be less waterproof then standard silnylon.

Really? I haven't used any of these tents so I don't know. But I would think that both Big Agnes and MSR would be very concerned about using less waterproof flies. They would have too many customers who would complain. It's not a niche market after all. No?

Actually I know all about the torrential rain as of late living in the Midwest. We just had a downpour about 4 weeks ago that only last 2 hours but in that two hours it dumped enough water to put the entire road under 8". I was driving in it as it started up and had to roll down both windows to keep the windshield from condensing so much rivulets were pouring down on the inside. Now if this were a once in a year thing around here it would be great but we no longer get showers here in East Central Illinois, we get these freak mini monsoons about once a week or so.

But if you want to talk about possible upgrades for tents, please help them to make me one that will take tornadoes on better. Any kind of anchoring I do does not seem to help.

As a five-year owner of BA's Seedhouse 2 SL tent with siliconized nylon fly with PU coating — I can tell you that it is rainproof. Ditto for the floor. Barring punctures, sitting on the floor laid on wet ground will not cause water to seep in.

But back to "misting silnylon" — Henry Shires and Ron Moak have both written many times that heavy rain can indeed "mist through" silnylon fabric. Given this, it's just amazing that some folks will still drone on that the silynon used for tarptents are rainproof and that Miguel's experience of "misting through" was either "hysterical" or somehow confusing rain with condensation.

> a combination of silicon and PU, silicon on the outside and PU on the inside. I take it the companies have done this because of the misting problem.

I suspect they have done it so they can tape seal the inside with ordinary seam-stick tapes. They are MUCH cheaper than the silicone tapes. You will see in many of the shelter descriptions the comment that the seams have been taped.

Cheers

Hi Miguel

> As I said in my original post it was truly wild rain. Think "you can't see more than three meters in front of you". How many of you have experienced that? For 10 hours straight?

I remember one time when we we racing for a known clear area because we could see the storm coming and didn't want to be camped under any big trees – they drop large branches in a storm. I got the tent up as it hit. By the time I had done all the stakes the bathtub floor was floating on about 1" /25 mm of water. The rain went on for a little while … It was also quite 'funny' at the time.

> cotton A-frame tents when I was a boy
I still have mine …

> I wonder how dilute it is possible to go with silicone and spirits,
Yeah, I wonder that too. Has anyone made the mix dilute enough that it can be put in a spray gun? If so, what solvent?

Cheers

To answer a few questions:

1. Dave Heiss:
Bob Ellenberg and Allison Miller have it right. It’s generally preferable to apply the treatment to the underside of the canopy since it significantly reduces the slipperiness of the silnylon. That’s a good thing for floors, but not as good for the outside of the canopy, since accumulating snow would to tend to cling and not slide as easily to the ground as it does with an untreated surface.

Though it’s a bit more trouble, applying the treatment to the canopy’s underside also helps protect it from damage. You’ll note that on almost all commercial backpacking tents, coatings (usually polyurethane) are applied to the inside surfaces, whether those surfaces are floors or flys.

2. Regarding the newer combo fabrics (PU + silicone), there’s at least one other reason for this design approach as noted in a BPL post I made a couple of years ago:

“The double coating adds weight, but improves water resistance to a degree (but not a lot in some cases if it’s very thin). It also makes it possible to heat-tape the PU-coated side of the fabric—not possible with straight silnylon since it’s so slippery. It further improves fire retardency enough that tents made from the fabric can be sold in those jurisdictions (seven states + Canada at last check) whose laws make most silnylon tents technically illegal because silnylon doesn’t measure up to their tougher fire retardency standards. As most backpackers know, standard silnylon will burn if exposed directly to a flame.

So far, I’ve tested only a single sample of this dual-coated fabric (the new Ultra Sil dry bag) and was not very impressed. You can see the leakage problem here.”

3. Roger:
Regarding the use of a spray gun to apply the treatment, I think it depends on the type of gun. Even a 1:5 mix is pretty viscous stuff, so it would probably take a fairly high pressure gun to atomize the slurry into fine enough droplets to apply evenly.

I tried using a manual spray bottle with no luck. On the other hand, brush-based application and cleanup is pretty easy, so it’s probably the best option for most individuals. For large scale commercial applications, however, the use of a proper gun (along with appropriate breathing mask and protective clothing) might be the way to go. Even so, you’d need to work quickly, since the slurry starts to cure quickly after it’s mixed. Take too long, and the mix would probably set up inside the spraying gear.

Likewise, thinning the treatment more than 1:5 might help for use in a spray gun, but I’m not sure at what point it would cease to be effective at solving the problem. I’ve tried mixes up to 1:15, but at least for floors, they had little effect on reducing slipperiness (about 1:3 seemed optimal). Not sure how well more diluted mixes would fare on canopies, however.

> cotton A-frame tents when I was a boy
I still have mine …

Those things could last till the end of time! Do you still use it? One thing I really like about them (especially the egyptian cotton ones) even though they weigh a million kilos, is that they do really well in the heat. At least better than nylon. I also like the natural feel of the material and the way they fit into the landscape (even the orange ones!!!).

I'm curious about "mineral" spirits. I tired to find it here in Japan about three years ago, but couldn't find anything by that name. What else might it be called?

Has anyone tried using something like dilute plastidip as a coating? It comes in clear and a few colors and will cure at room temp. You can thin them to spray or I'd image you could brush, sponge or squeegee them as well.

http://www.plastidip.com/index.php

I've used both the dip and the aerosol versions for tools, jigs and vacuum tables etc, but have not tried using them as a fabric coating.

My concern might be weight over some of the other liquid silicone rubber (LSR) coatings that I *think* most of the manufacturers might use for this purpose.

How about using aerosol silicone like Silicone Water-Guard, or Scotchgard as described in link below?

http://www.hammockcamping.com/Free%20Reports/Silnylon.htm

What I noticed in that article is this paragraph:

"Note that silicone treatments do not completely 'seal' fabrics or seams in the same manner as urethane coatings. Instead, silicone simply causes water to bead up on the surface exposed to rain, allowing it to run off or evaporate instead of wetting the fibers and soaking through to the other side. Thus silnylon is 'waterproof' only up to a certain pressure; at higher pressures, water can be forced through the fabric. Fortunately even a heavy driven downpour does not generate enough pressure to cause well-treated silnylon to leak."