Tarp "misting", "leakage", condensation etc.

[BillyBob58]

the Solar Still concept, but I guess that is not really correct. Warm, moist ground is going to be giving off water vapor, and the tarp is the obvious cool place for it to condense....................

Jim

I think you are def on to something, that is what I have always suspected. I get that winter or summer. But my backyard, where I get it most, is usually the wettest place I have hung. My back yard does not drain fast at all.

[Gary_R]

I have had my tarp get wet to the touch but never "misted" on me..

[Theo]

I have had that about a bazillion times. I have it often when it has not even sprinkled.

So I'm pretty sure it's just some form of dew/condensation. Just to throw another monkey wrench into the discussion, I'm pretty sure every time or at least most times I have ever had this was in my backyard. I cannot say for sure if I've ever had that happen on a backpacking trip. But if it has, it has been seldom for me.

Most backyards are covered in grass. Grass, by nature, will release more water vapor than leaf litter. So, yeah, there is going to be more condensation in your backyard than in the woods.

[Jsaults]

Good point! And as I recall a number of times I have pitched my hammocks on State Park campground manicured lawns and experienced under-tarp condensation.

Jim
Doh!

[T-BACK]

Couldn't find the original post, but there was a bit of discussion about sil-nylon "leaking" or "misting through" some time ago.

This past Saturday, during a hang in the wilds of northern Pittsburgh PA (my Father's back yard!) I awoke to find the underside of my WB SuperFly lightly coated with moisture. There were a few light showers overnight, nothing to get excited about, and my WBSF is pretty new (only a few nights out).

But the conditions were very humid, with temps falling from the 80s down to the mid-60s. I simply wrote it off to condensation due to the atmospheric conditions. I wonder how many complaints of "leakage" or "misting through" are due to simple condensation?

Jim

What you are describing sounds like condensation. Be thankful you were under a tarp and not buttoned up inside a single walled tent. Condensation is always an issue when you are breathing under a barrier. Even netting raises the humidity level quite a bit. That's why I only use mosquito netting in the summer and not the finer Noseeum netting. That said, I can tell you first hand that misting does happen with some grades of fabric. I have never had any issue with spinnaker misting through but sil-nylon is another story. I got some 2nds from Noah Lamport a while back and made a beautiful dark, forest green tarp. The only problem was that you could actually watch the rain drops push their way through the fabric and transform into an aerosol mist. Now, if there was enough wind, the moisture did not settle much at all and just kind of floated around until it was swept from under the tarp. This is misting. Not drops of condensation being knocked lose from the tarp by raindrops but a fog that forms in the air. During my testing of this tarp it was set up immediately before a storm (Honey, there goes our crazy neighbor again running outside into a thunderstorm) and was observed from under an umbrella so that I would not be breathing warm air onto the cool fabric. In contrast, and set up right next to this tarp was my OES tarp. There was NO misting going on in there. I later made doors for the OES out of the same NL green fabric and the misting appeared at the ends of that tarp too. My Speer Winter Tarp never misted through even though I put it through 40 straight days of rain on the AT.

Several tent and tarp manufacturers as well as fabric suppliers have addressed this issue over the years either by stating that the misting is not enough to cause your sleeping bag to get wet or to definitely state that their supplier of fabric has come up with a treatment method that guarantees there will be no misting. A simple Google search will turn up many discussions on this very matter.

I believe that the QC on most of the sil fabric used for shelters has gotten better and might be where it needs to be to meet our wants and desires with the cream of the crop possibly being MLD's "Shield Sil".

The old sil was perfectly good for what it was designed for, stopping me from hitting the ground too hard after I jumped from an aircraft. However, zero air porosity just can't be compared to the force generated by a dense drop of rain falling at terminal velocity. Its hard for a few threads of lightweight fabric to try and fully stop a bullet like that.

I think it's up to the manufacturers to insist on high quality sil from their suppliers and I think this is happening more and more even leading up to a shortage of Spinnaker fabric throughout the industry due to quality concerns.

My hat is off to all who have fought through the years to make the Sil-nylon manufacturers understand our needs, as outdoorsmen (and women), and get them to start producing a product that we can trust our lives to when the going gets tough.

[raiffnuke]

What you are describing sounds like condensation. Be thankful you were under a tarp and not buttoned up inside a single walled tent. Condensation is always an issue when you are breathing under a barrier. Even netting raises the humidity level quite a bit. That's why I only use mosquito netting in the summer and not the finer Noseeum netting. That said, I can tell you first hand that misting does happen with some grades of fabric. I have never had any issue with spinnaker misting through but sil-nylon is another story. I got some 2nds from Noah Lamport a while back and made a beautiful dark, forest green tarp. The only problem was that you could actually watch the rain drops push their way through the fabric and transform into an aerosol mist. Now, if there was enough wind, the moisture did not settle much at all and just kind of floated around until it was swept from under the tarp. This is misting. Not drops of condensation being knocked lose from the tarp by raindrops but a fog that forms in the air. During my testing of this tarp it was set up immediately before a storm (Honey, there goes our crazy neighbor again running outside into a thunderstorm) and was observed from under an umbrella so that I would not be breathing warm air onto the cool fabric. In contrast, and set up right next to this tarp was my OES tarp. There was NO misting going on in there. I later made doors for the OES out of the same NL green fabric and the misting appeared at the ends of that tarp too. My Speer Winter Tarp never misted through even though I put it through 40 straight days of rain on the AT.

Several tent and tarp manufacturers as well as fabric suppliers have addressed this issue over the years either by stating that the misting is not enough to cause your sleeping bag to get wet or to definitely state that their supplier of fabric has come up with a treatment method that guarantees there will be no misting. A simple Google search will turn up many discussions on this very matter.

I believe that the QC on most of the sil fabric used for shelters has gotten better and might be where it needs to be to meet our wants and desires with the cream of the crop possibly being MLD's "Shield Sil".

The old sil was perfectly good for what it was designed for, stopping me from hitting the ground too hard after I jumped from an aircraft. However, zero air porosity just can't be compared to the force generated by a dense drop of rain falling at terminal velocity. Its hard for a few threads of lightweight fabric to try and fully stop a bullet like that.

I think it's up to the manufacturers to insist on high quality sil from their suppliers and I think this is happening more and more even leading up to a shortage of Spinnaker fabric throughout the industry due to quality concerns.

My hat is off to all who have fought through the years to make the Sil-nylon manufacturers understand our needs, as outdoorsmen (and women), and get them to start producing a product that we can trust our lives to when the going gets tough.

Nice response. Thanks.

[Beast 71]

I have had that about a bazillion times. I have it often when it has not even sprinkled.

Me too! I'm guessing that the largest source of vapor under the tarp is me. I've gotten alot of frost on very cold and dry nights and it's mostly around my head end. That makes me think that breathing is the culprit.