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Why make tents out of sil nylon anyways?


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  • #1284634
    Mike Sobr
    Member

    @breeze

    Locale: Southeaster

    I have always wondered why so many of the tent makers use sil for the main bodies of the tents as it is prone to stretching and even worse has a propensity for wicking, transferring, and otherwise allowing moisture to collect inside and after owning several over the years can't quite figure it out.
    I can only guess that since they seem to be geared towards the UL crowd that it must be for saving a few ounces over using regular tent fabric which seems to be pretty light anyways but maybe somebody can shed some light as countless posts over the years have been about how to mitigate this moisture problem when using sil tents of all kinds.

    #1829249
    Jeff M.
    BPL Member

    @catalyst

    As far as I can tell it's because its relatively cheap and light and the moisture problems are manageable.

    #1829251
    Travis Leanna
    BPL Member

    @t-l

    Locale: Wisconsin

    >countless posts over the years have been about how to mitigate this moisture problem when using sil tents of all kinds.

    That's NOT a problem due to the silnylon being used. ALL tent fabrics used today will have moisture problems. The reason you see a lot of threads about condensation is that the majority of shelters here are single-walled which creates somewhat of a need to find ways to mitigate the issue.

    #1829252
    drowning in spam
    Member

    @leaftye

    Locale: SoCal

    The PU coated fabrics I've seen are less expensive than silnylon. Examples of this can be seen in the pricing on Quest Outfitters or of the SMD Skyscape Trekker vs the Skyscape Scout.

    The reason UL tent manufacturers use silnylon is because it weighs less than PU coated fabrics, and because it's much less expensive than cuben fiber.

    #1829261
    Stephan Doyle
    Member

    @stephancal

    Silnylon is basically PU fabrics gone LW.

    Cuben has some unique properties and is in a different class altogether.

    #1829266
    Dan @ Durston Gear
    BPL Member

    @dandydan

    Locale: Canadian Rockies

    Does silnylon really weigh significantly less than PU nylons? Anyone got hard numbers? I thought the whole 'silnylon is lighter' idea came about because silnylon was easily available in 30D nylon, whereas a few years ago it was hard to find a PU coated nylon that was less than 70D. So of the two options (30D silnylon or 70D PU-nylon), the silnylon was a lot lighter. Apples to apples though (30d silnylon vs. 30d PU nylon) I'm not sure there's much of a difference.

    It's widely known that 30 denier nylon weighs 1.1oz, and with a silicone treatment it typically weighs about 1.3 – 1.4oz. How much does a 30D PU nylon weigh? I think I looked it up a while back and it was 1.4 or 1.5oz….so barely heavier. Maybe 1oz total for an entire tent. Plus you can get PU nylon in less than 30D (ie. Nemo Obi Elite tents use 10D and 20D PU nylons) so it would be lighter still.

    I've long been an advocate for PU nylons over silnylon. The slipperiness of silnylon sucks and the hydrostatic head ratings are the usually the bare minimum. For maybe 1oz per tent you could totally solve this.

    #1829280
    Franco Darioli
    Spectator

    @franco

    Locale: Gauche, CU.

    Dan I will quote from some manufacturers that use silnylon as well as other fabrics .
    Macpac:
    Strength
    Using double ripstop nylon makes UV30™ very strong and the silicon coating on both sides of the fabric acts to increase the tear strength of UV30™. The silicon coating doesn't bind or lock the weave but allows a certain amount of give in the weave increasing its capacity to absorb tension. This means the fabric has significantly higher tear strength than a similarly constructed fabric with polyurethane coating.

    Hilleberg :
    The Silicone Connection
    In 1975, Bo Hilleberg received a sample of a new, lighter, more waterproof fabric. When Bo cut the edge of the sample and tried to tear it, he couldn’t. The fabric, Bo discovered, was coated with silicone, rather than the usual polyurethane. And while this new fabric was indeed very light and waterproof, it was also exceptionally strong. It was exactly what Bo had been looking for, and our Kerlon fabrics were born.

    (Not all silicone-coated fabrics are created equal, however)

    Stephenson's

    MATERIALS:
    Fabric is ultra high tenacity 30d. ripstop Nylon with a very durable silicone waterproof finish (made for parachutes and hot air balloons, thus the color choices!), is 3 times stronger than fabric usually used for fly on other tents, (and which we used till 1995)

    Note that, as Hilleberg is very keen to point out ,not all siliconised fabrics are the same, but that is true for the other types too.

    Franco

    #1829288
    Michael Cheifetz
    BPL Member

    @mike_hefetz

    Locale: Israel

    It might not be true anymore but it used to be in my experience that the PU coatings would peel over time and from what ive seen the Si doesnt …i assume cause its impregnated into the fabric…

    #1829313
    kevperro .
    BPL Member

    @kevperro

    Locale: Washington State

    It works… a proven light-weight fabric. Like all materials it has it's up-sides and down-sides.

    If you don't want to deal with those traits, you buy a tent or tarp made with another material.

    #1829435
    carl becker
    Spectator

    @carlbecker

    Locale: Northern Virginia

    It has been my experience that tents get wet inside because of holes or condensation. The PU tents I have owned have shed their coating and become worthless. I have not had a silnylon tent for very long but I like the weight, price and strength. All of my nylon tents suffer from stretching, but it is a solvable problem. Currently I have a tyvek, spinaker cloth and silnylon shelters.

    #1829444
    Jon Denham
    Member

    @jmden

    Franco hit on the other big advantage to silnylon. The silicon actually strengthens the nylon while PU actually reduces the strength of nylon. This is well known in the industry. 70D coated with PU has about 1/2 the tear resistance, as I recall, than 30D silicone coated both sides. That is worthy of consideration when you go to build your shelter. Although, you have to be careful now as many manufacturers are using a PU/silicone combo (supposedly more env. friendly) and the result may be a weaker 'silnylon'. You have to get the test results from the manufacturer for the material you are using to know.

    #1829485
    David Olsen
    Spectator

    @oware

    Locale: Steptoe Butte

    "Does silnylon really weigh significantly less than PU nylons? Anyone got hard numbers? I thought the whole 'silnylon is lighter' idea came about because silnylon was easily available in 30D nylon, whereas a few years ago it was hard to find a PU coated nylon that was less than 70D. So of the two options (30D silnylon or 70D PU-nylon), the silnylon was a lot lighter. Apples to apples though (30d silnylon vs. 30d PU nylon) I'm not sure there's much of a difference.

    It's widely known that 30 denier nylon weighs 1.1oz, and with a silicone treatment it typically weighs about 1.3 – 1.4oz. How much does a 30D PU nylon weigh? I think I looked it up a while back and it was 1.4 or 1.5oz….so barely heavier. Maybe 1oz total for an entire tent. Plus you can get PU nylon in less than 30D (ie. Nemo Obi Elite tents use 10D and 20D PU nylons) so it would be lighter still.

    I've long been an advocate for PU nylons over silnylon. The slipperiness of silnylon sucks and the hydrostatic head ratings are the usually the bare minimum. For maybe 1oz per tent you could totally solve this.

    "

    PU coating is, generally speaking, no more waterproof by weight than silicone coatings.
    You will find the PU coatings that have a higher HH than Sil coatings also are double or triple the weight.

    Richard posted his HH numbers for all kinds of coatings and weights. Search there.

    Where did you find 30d PU?

    #1829501
    Brian UL
    Member

    @maynard76

    Locale: New England

    Nemo make tents with 10/20/30 denier PU nylons.
    Maybe someone has used them and can chime in on how they preform?
    I had the same question when looking at the new lightweight tent flys. I could see where I would sacrifice some tear strength for lower cost (Im assuming) and less stretch. I think, besides weight the biggest advantage cuben has over silnylon is it doesn't stretch.

    #1829601
    Dan @ Durston Gear
    BPL Member

    @dandydan

    Locale: Canadian Rockies

    I'm willing to believe silnylon is stronger than PU nylon, but the claims that silnylon is 3x as strong as regular nylon, while PU coated nylon is actually weaker seem awfully radical. Does anyone have evidence for these? This would be a cool BPL article.

    In any case, use silnylon for the canopy where strength is needed and use PU nylon for the floor where a non-slippery fabric is desired.

    "Where did you find 30d PU?"

    It's been a while since I looked into this. I think what I did was I found the weight for regular 70D nylon and compared that to 70D PU nylon to find the weight of the coating. Then I just applied that weight to 30D fabrics to estimate the combined weight.

    Lets see….Quest's PU coated 70D rip stop nylon is 2.2oz before coating and 2.65oz after….so 0.45oz for the treatment. So theoretically if you put that same PU coating on 1.1oz 30D nylon, you'd wind up at 1.55oz….vs. 1.3-1.4oz for silnylon.

    Now where to get some for my floor….

    #1829607
    David Olsen
    Spectator

    @oware

    Locale: Steptoe Butte

    The factory specs I have seen-

    30d type 66 nylon with .25 oz coat range from 15 to 25 lbs tear strength.

    70d type 6 nylon with a .75 oz PU coat is 9 lbs.

    70d type 6 with a .5 oz Sil/PU blend coating is 18 lbs.

    #1829610
    Jon Denham
    Member

    @jmden

    …is using 10 and 20 denier PU coated stuff: http://www.nemoequipment.com/nemo2011-obielite-tent

    I would think that that would not be very strong in terms of tear resistance unless they've come up with some new formulation. PU weakening to nylon is an industry wide consideration when picking a fabric for your application.

    Westmark's 70D with 3/4 oz. PU FR/UV coating fabric has a 2-5 lb. warp and fill tear strength, + or – 10%.

    Westmark's 30D 'ultrasil' silnylon has a 12-14 lb warp and fill tear strength.

    These are numbers right off Westmark's testing for recent fabric lots.

    I think this might help demonstrate why you don't see too much PU coated nylons available to Joe Public less than 70D.

    #1829612
    Jon Denham
    Member

    @jmden

    David,

    Have you found 70D sil/PU available to Joe Public?

    #1829616
    David Olsen
    Spectator

    @oware

    Locale: Steptoe Butte

    I have a couple of small rolls of red 70d .5 oz sil/pu. I believe other fabric sellers have more colors. Coating combinations seem to vary tho.

    I thought it would be a big seller when people started complaining about stretch in 30d and the need for tarps impervious to fire hoses and waterfalls, so I bought some when it came around, but have sold only a handful of tarps made from it.

    Another advantage to the 70d double thick sil/pu coat is that being coated on one side and a blend, it is not slippery like the 30d sil.

    #1829639
    Jerry Adams
    BPL Member

    @retiredjerry

    Locale: Oregon and Washington

    I've used silnylon for bivy bottom and it does soak through a bit. If I coated it with mineral spirits:silicone it's pretty waterproof. I just bought some Shield which is supposed to be better. But this has nothing to do with tents.

    I've used silnylon for pack. When something that absorbs water is inside against silnylon, it soaks through some in rain. Again, coating with mineral spirits:silicone fixes this. Again, this has nothing to do with tents.

    I've had a little "misting" in tarps from heavy rain, but as other people have talked about, it's hard to know if this was leakage or condensation on the inside being knocked off by rain drops. Some condensation is probably unavoidable so even if the fabric was totally waterproof, this would still happen.

    In my experience, the waterproofness of silnylon is fine for tents, no reason for anything better. Even the 2nds commonly available that isn't as good.

    If the tent wall rests against sleeping bag, then maybe it's not perfect, but even that's probably okay.

    #1829659
    Jon Denham
    Member

    @jmden

    jerry, What do you mean by 'mineral spirits:silicone' exactly?

    #1829668
    Steven McAllister
    BPL Member

    @brooklynkayak

    Locale: Arizona, US

    This argument comes up a lot.

    Although I keep hearing about the potential for silnylon to leak under high pressure, I have never seen it in strong blowing rain.

    The stretchy aspect and the tendency to sag in cold and rain is a non-issue if pitched with that in mind.

    Because of it's weight and cost, it is a good compromise.
    I personally would never buy a PU coated shelter when silnylon isn't that much more $.

    #1829676
    Mike Sobr
    Member

    @breeze

    Locale: Southeaster

    The reason I started this thread is that we have a typical department store type family-sized Coleman tent that we have enjoyed for well over 15 years and it's been through some crazy abuse from the kids and bad weather and stored in the heat and played tag football inside but it still looks great and never leaks and doesn't have the problems of my modern sil tents used for UL backpacking.

    Of course when we crammed 10 scouts in there camping down by the river in a rainstorm it got damp but with just 4 of us never had a drop of condensation….

    compared to my sil tents that wet through overnite while testing them in the backyard unoccupied with "NO OCCUPANTS"….. which means to me water is moving through the fabric unlike my 15 year old dinosaur tent.

    Surely a tent maker will chime in and give us the skinny on this sil material as at least a few great tarp tent makers that we know and love are pretty darn smart about designing great shelters and surely there is a logical reason for it.

    #1829686
    Steven McAllister
    BPL Member

    @brooklynkayak

    Locale: Arizona, US

    Regarding: "compared to my sil tents that wet through overnite while testing them in the backyard unoccupied with "NO OCCUPANTS"….. which means to me water is moving through the fabric unlike my 15 year old dinosaur tent."

    That does not mean water is moving through the fabric. Condensation happens on both sides of the fabric on any material, doesn't matter if people are inside or not, condensation condenses on solid objects when the dew point is reached.

    This is especially true when it rains, but rain is not required.

    #1829691
    Franco Darioli
    Spectator

    @franco

    Locale: Gauche, CU.

    My guess is that you are comparing two totally different designs.
    Knowing exactly the two tents in questoin may help.

    To illustrate…
    condensation
    The morning after this shot was taken , I woke up inside an almost totally dry Contrail, my mate had his tarp dripping on him .
    (we were camped not far from a river, he was closer to it than me )
    Now the reason why his tarp was dripping had nothing to do with the fabric of his shelter (spinnaker ?) but that it was pitched very low so that both ground evaporation and his breath solidified upon contact with the fabric.
    If his tarp had been made with silnylon and my Contrail out of spinnaker the result would have remained the same (or very close to it…)
    As I mentioned in another thread , the last time I camped next to several other tents, the next morning after inspecting my SS2 and my mate's Moment (both silnylon) Tarptent got three orders from campers that spent a very wet night inside their shelters. (mostly polyester and taffeta nylon, but again nothing to do with the material, just lack of air flow…)
    Franco

    #1829695
    Sam Farrington
    BPL Member

    @scfhome

    Locale: Chocorua NH, USA

    The air gets a little thin when we over generalize about these materials and coatings.

    Both vary greatly in quality, making the generalizations of little value.

    For example, I have some PU nylon from Warmlite and some from The North Face that were both purchased 15-20 years ago. They each weigh 1.6 oz. per sq. yd. with the coating. They are different – the TNF coating is flat, the WL is shiny.
    Both have survived to this day many winters in a cold basement without peeling.

    I did put two layers of the WL together, coatings facing inward but not bonded, and used it for a floor for many years (3.2 oz/sq/yd!) because I was tired of leaky 70 denier PU coated nylon floors. It was actually lighter than the floor material that came with the tent, and worked very well, but eventually, areas of the inner under me did become damp in real deluges – but no water drops.

    On the other hand, I have a Bug Dome floor from Wilderness Experience that is PU coated, don't know the denier, between 1-2 oz/sq/yd, and it never even got damp on the inside for several years before I replaced it with silnylon to save weight.

    However, my old Eureka solo tent outer was less than 70 denier, and after 5-7 years the PU coating peeled in places, and even where it remained, heavy wind driven rain (but not your average rain) would penetrate and drip into the vestibule.

    Note – about the denier – pretty sure that refers to weight of the fibers, not the fabric. Pretty sure you can have a higher denier, lightened by a less dense weave, and a lower denier, heavier due to a more dense weave. So denier does not = weight.

    I've never been tempted to use the better PU coated nylons for floors because I do believe the data that the silnylon is stronger than the same thing PU coated, and super quality silnylon is available for much less than cuben. Also, there is very high HH cuben that weighs no more than the silnylon, at a price of course.

    I also have silnylon that is over ten years old that at least appears to be as new as the day it was purchased. But most of what I have, old or new, that has been tested by Roger Caffin, has a quite low HH, not much over 1000mm. There is an awful lot of this junky stuff around. Caveat emptor!

    Hope the above illustrates that due to the wide variations in quality we need to be specific about particular fabrics, available from particular sources, or at least used in particular products, when evaluating these materials. If you need further proof of this, look at Richard's many test results.

    The ultimate tent material would be flexible polyester, and not sag; would be highly vapor permeable and therefore not need a liner or inner tent; would have a super HH, at least 3000mm; and would be available at reasonable cost.
    Since we don't have anything like that, compromise is the order of the day, and that's why tents are made out of silnylon anyways.

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