Tarptent question

[10-K]

I took my new TT Rainbow out on a 3 night hike this week and on the last night we were in one of those "howling winds, driving rain" storms on the side of a mountain.

One thing I noticed is that a fine mist seemed to somehow come through the tent walls - at first I thought it was my imagination but I put my headlight on and could see the reflections of the mist. It was almost like someone was spraying a flower mister every few minutes or something.

It wasn't devastating and nothing go seriously wet but in the morning everything in my tent was damp even though no rain entered the tent directly. Condensation was not an issue.

Is this something unique to Tarptents? I've been through some serious weather, including a tropical storm, in my Lunar Solo/Duo and have never experienced this before.

[bigcranky]

I don't know if there is any real difference in the two brands, but in my own experience, I had the misting in a Double Rainbow and went through a similar storm in a Lunar Duo without. That said, it's really difficult to compare the strength of the rain storm several months apart...

[swamp dawg]

Go to the Tarptent home page and click on the Frequently Asked Questions section. Look for the question about sylicone impregnated nylon and the misting problem. Henry explains the misting problem. We have serious rain down here in the southeast as oppose to West coast rain. Heading north......swamp dawg

[couscous]

Q: Is silicone-impregnated ripstop nylon waterproof?.
A: Silicone impregnated ripstop nylon is waterproof within "normal operating conditions." In very heavy rain and high velocity wind-driven rain some extremely light interior misting is normal and equivalent to increased interior humidity.
- http://www.tarptent.com/faq.html

[10-K]

Dang, how about that... "high velocity wind-driven rain" is a perfect description of what we were in.

At least I'm not going crazy or imagining things....

So I wonder if the liner would address that - probably so?

[Franco]

Yes you can get misting by penetration.
The silnylon used by TT and SMD (and others...) is rated at 1200mm , that means it can hold a column of water 1200mm high without leaking.
If the rain drops are large enough they build up more pressure than the 1200mm rating can hold.
Not common at all but it does happen.
BTW, there are several other tent fabrics in use that (inc Epic and polyester) have a rating between 800 and 1500 mm (31"-59")
Polyester has usually a PU coating. The thicker the coating the more waterproof it becomes but the heavier it will be.
PU coating also weakens the fabric and it can (and eventually will) perish, ( the sticky/smelly tent fabric you read about)
I did some tests with the TT sil and verified the waterhead.
Just to try it , I painted a very thin coat of silicone on a piece of the fabric (much higher dilution then when seam sealing) that took the waterhead to about 2000mm.
But I have not bothered doing any of my shelters with that.
Franco
[email protected]

[Franco]

The mist penetrating the silnylon has very little pressure so it will not penetrate the liner. This is a picture of the liner holding about 16 liters of water.

I left it there all day, no drips...
Franco

[10-K]

Of course like Big Cranky said you can't compare storms readily but I've spent more than 90 days in my Lunar Solo/Duo tents and those included some serious storms - worse than the one last night - and I've never had any kind of misting problem -ever-. Strange that it would happen with my Rainbow on the first storm.

Are you sure they use the exact same material?

Yes you can get misting by penetration.
The silnylon used by TT and SMD (and others...) is rated at 1200mm , that means it can hold a column of water 1200mm high without leaking.
If the rain drops are large enough they build up more pressure than the 1200mm rating can hold.
Not common at all but it does happen.
BTW, there are several other tent fabrics in use that (inc Epic and polyester) have a rating between 800 and 1500 mm (31"-59")
Polyester has usually a PU coating. The thicker the coating the more waterproof it becomes but the heavier it will be.
PU coating also weakens the fabric and it can (and eventually will) perish, ( the sticky/smelly tent fabric you read about)
I did some tests with the TT sil and verified the waterhead.
Just to try it , I painted a very thin coat of silicone on a piece of the fabric (much higher dilution then when seam sealing) that took the waterhead to about 2000mm.
But I have not bothered doing any of my shelters with that.
Franco
[email protected]

[10-K]

Impressive!

The mist penetrating the silnylon has very little pressure so it will not penetrate the liner. This is a picture of the liner holding about 16 liters of water.

I left it there all day, no drips...
Franco

[Snowleopard]

It can be hard to distinguish between misting coming through the fabric and condensation on the inner surface being knocked off by the force of rain hitting the exterior surface. My guess would be it's condensation being banged off by the force of wind and rain. The rain was probably cold which would contribute to condensation. The liner probably would help some, but I can't guess how much.
Much more discussion here: http://www.backpackinglight.com/cgi-...to_post=111477
--Walter

[10-K]

No, believe me, this was definitely misting. It has a certain force to it - like it was being pushed (or should I say, sprayed).

In fact, I had a sponge with me and kept the tent wiped down even though it wasn't condensing enough to be absolutely necessary. With the winds blowing 40+ mph ventilation was not an issue at all.

It can be hard to distinguish between misting coming through the fabric and condensation on the inner surface being knocked off by the force of rain hitting the exterior surface. My guess would be it's condensation being banged off by the force of wind and rain. The rain was probably cold which would contribute to condensation. The liner probably would help some, but I can't guess how much.
Much more discussion here: http://www.backpackinglight.com/cgi-...to_post=111477
--Walter

[ronmoak]

Of course like Big Cranky said you can't compare storms readily but I've spent more than 90 days in my Lunar Solo/Duo tents and those included some serious storms - worse than the one last night - and I've never had any kind of misting problem -ever-. Strange that it would happen with my Rainbow on the first storm.

Are you sure they use the exact same material?

To be accurate, both Henry and I purchase our Silnylon from the same source. However, they carry two different styles of Silnylon with different coatings.

Henry uses one version, I use the other. The version I'm using has more coating. I believe Henry likes the other version because it's stretch works better with the shape of his tents. But, you'll have to check with him directly to confirm that.

Since switching to the new Silnylon several years ago, I've had no reports of misting on our tents.

Also for anyone interested, we've started our Scratch and Dent sale today. You can pickup a Lunar Duo at a really good price.

Ron

[10-K]

Also for anyone interested, we've started our Scratch and Dent sale today. You can pickup a Lunar Duo at a really good price.

Ron

The Lunar Duo is, without a doubt, my favorite piece of gear. You hit the jackpot with that one.

I recommend it every chance I get - at the S&D price of $240 it's no-brainer.

[Franco]

Just realised looking at the larger shot above (I cliked on a thumbnail...) that what I posted is in fact a piece of silnylon not the liner at all.
Can't find a shot of the liner but I had it set up in a similar way but with much less water , still several liters so much more that a few drips from mist or condensation dripping.
Franco

[Tipi Walter]

Here's some pertinent info you may find interesting from Wikipedia:

"Rain resistance is measured as a hydrostatic head in millimetres (mm). This indicates the pressure of water needed to penetrate a fabric. Heavy or wind-driven rain has a higher pressure than light rain. Standing on a groundsheet increases the pressure on any water underneath. Fabric with a hydrostatic head rating of 1000 mm or less is best regarded as shower resistant, with 1500 mm being usually suitable for summer camping. Tents for year-round use generally have at least 2000 mm; expedition tents intended for extreme conditions are often rated at 3000 mm. Where quoted, groundsheets may be rated for 5000 mm or more."


So, I went looking for my Hilleberg tent's rating and found the Kerlon 1800 silnylon fly has a 3,000 mm figure---and here's the best of all: The floor is 100 denier with a 7,000 mm rating.

[garbanz]

Misting occurs with the tarptents because of big deluge type rain drops spraying condensation downwards. Thats why the only thing in my pack that isnt lightweight is the tent.

[Franco]

BTW, Ron is correct , of course, about the silnylon used by him and TT.
The floor in the TT is the same type used for the fly by SMD.
It has some PU content so it is a bit more "waterproof" but indeed it has less stretch.

Franco

[skinewmexico]

I've always wondered about using the same mix used for seam sealing, and just painting the flat area on the top of the tent. Wish Franco would test that.

[Bags4266]

10-K the same thing happened to me last year in my contrail. Only difference is that I actually got soaked. I had to take out my poncho to drape over my bag, that result was of course was a wet bag due to the poncho not breathing. Had to take a zero day to dry everything out. Never had these problems in my double wall tent and been in many heavy long hour rain storms.

[10-K]

I've always wondered about using the same mix used for seam sealing, and just painting the flat area on the top of the tent. Wish Franco would test that.

I had the exact same idea.....

By the time it's seam sealed, add a liner and coat the top I'll have the only 4 lb UL TT on the planet!

The design is fantastic but the misting issue is worrisome living down here in the SE like I do... I don't care about condensation - I can cope with that by site selection and a sponge but the misting issue is unavoidable and you can't wipe it up because it's a spray.

And, I must say it was information that was readily available - my bad for not doing my research. I'm going to hang in there with it but it is a downer.

I'd give anything to have a Rainbow made out of the material SMD uses.

(well, not *anything* but you know what I mean....)