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 $.

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.

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.

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

To illustrate...

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

Edited by Franco on 01/25/2012 19:02:16 MST.

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.

I think that's well said from what little I know.

My best (don't quote me on this) understanding/recollection of 'denier' is that it is some kind of measure of the individual fiber diameter. So, in a general way, by itself, it can give a general sense of the weight of one fabric vs. another, but in actual practice you need to get the actual weight per square area of one fabric vs. another with different weaves from different mills, etc. Some weaves may be tight or loose, etc.

Denier is the weight in grams of 9,000m (yes nine kilometers) of that particular fiber (30D= 9000m of 30d nylon)
Linear not square.
Franco

There it is. So, it does essentially relate to diameter/size of the fiber.

"The ultimate tent material would be flexible polyester, and not sag"

Polyester is weaker than nylon by weight. The stretch of the nylon is a prime reason
it holds up to shock loads so much better than polyester. Cuben Fiber is polyester, but
has a Spectra scrim to impart strength.


"would be highly vapor permeable and therefore not need a liner or inner tent"

Inner tents add extra warmth & decrease condensation, some arctic tents are triple
walled.

"would have a super HH, at least 3000mm"

Not needed for many uses. Many older tents made of cotton or uncoated nylon, had HH of below 500, some well below. They were very breathable and if were light enough, would be a good modern choice for some climates. For example, I spent dry comfortable nights during snow and mixed rain in Teepee's made of two layers of uncoated 30d built from old parachutes by Airforce Survival School instructors. Also have used similar one layer shelters, but with a fire inside to drive out moisture.

Franco - thanks for the spec info on denier - will try to remember.
On second thought, that's hopeless. Will copy and past your post and file it in my highly organized filing system.

David,
When I'm camped in the open above timberline at 11-13K feet, the wind is howling, the rain seems to be blowing in every direction except vertical and is creating instant ponds with their own tidal waves, and the tent is single wall, then I want at least 3000mm HH. No fair asking why the h*** I would camp there in the first place anyways. Maybe I broke my leg.

People lately seem to make a big deal about HH.
In the old days, we were fine with treated cotton, silk and others that had very little HH.

We would get some dampness and water on our no-DWR sleeping bags, mopping the walls of our tent from time to time. It was no big deal and you slept OK.

So what's the big deal?

"David,
When I'm camped in the open above timberline at 11-13K feet, the wind is howling, the rain seems to be blowing in every direction except vertical and is creating instant ponds with their own tidal waves, and the tent is single wall, then I want at least 3000mm HH. No fair asking why the h*** I would camp there in the first place anyways. Maybe I broke my leg."

I am a belt and suspenders person and I understand. I even owned a Goretex Sleeping
bag once and used it with a tarp AND a bivysack when on long spring trips above treeline.

I also wore a rubber rain suit OVER a Goretex one for a winter trip on the coast of the
Olympics. 5 inches of rain an hour gives one a new outlook on HH.

Waterproof pads play an important role too when used with light duty ground sheets.

I like layers, can you tell?