nikwax waterproofing

[Keegan Wagner]

I have just gotten back from a weekend backpacking trip. It thunder-stormed one of the nights, so when the rain came down real hard I got misted in the face with my sil-nylon tarp. this is probably do to it's made of seconds's(although there's no cosmetic flaws.) I was hoping I wouldn't have to make a whole new tarp. So was thinking I could treat both sides a couple times with nikwax solar waterproofer they have for tents. What do you think
Thanks.
P.S the tarp shed all the light/moderate rain perfectly, just not the heavy rain
http://www.nikwax.com/en-gb/products/productdetail.php?productid=498&activityid=1&itemid=-1&fabricid=-1

[Jeffrey Kuchera]

Check this thread out here

[EndoftheTrail]

So-called waterproofing.

Temporary water repellant is all it is. Spray it on the outside surface and it will help get raindrops to bead up and slide off — up to a point. After more than ten or twenty minutes of rain — if your sil tarp lets in the rain — then rain will start seeping through.

If a fabric itself isn't rainproof, then no amount of spray on will make it so. It's why we haven't all turn our 3oz. wind jackets into rain jackets simply by spraying.

With a regular piece of nylon, you could spray the repellant on the outside AND coat a PU coating on the underside for true rain proofing. However, I don't think PU coating will work with silnylon.

Another option might be to get a tube of SilNet — thin it out appropriately — and coat a layer on the underside. Expect this to add a few ounces of weight though.

[Jeffrey Kuchera]

As Ben suggests spraying on some Nikwax really isn't the solution and will just mask the problem. Give the thread I posted a read. I found the discussion of "misting" there to be quite helpful. The solution to your problem is covered briefly in the thread and involves painting your tarp with a mixture of odorless mineral spirits and silicone caulk. Many people here at BPL have reported great success thinning out silicone with mineral spirits and applying it to their silnylon tarps.

[Jeffrey Kuchera]

Here is the link you really need though I suggest you read the first link I posted too.
Instructions for treating silnylon

[Roger Caffin]

Hi Keegan

Be aware that many will be of the opinion that what the 'real hard' rain was doing was knocking condensation off the underside of your tarp. This doesn't happen with light rain because it doesn't hit hard enough. A sheet of plastic might behave the same.

Cheers

[Jeffrey Kuchera]

Another misting discussion

As Roger points out some folks believe in "misting" and some folks believe that "misting" is merely condensation being knocked off the inside of the tarp, fly, tent, etc. by the rain hitting the outside of the tarp. Whether or not you believe in "misting", it is a fact of life that rain will knock condensation gathered on the underside of tarps, single wall tents, flys, etc. down onto you. The first and third threads I posted discuss this topic of condensation as well as many other topics related to the misting phenomenon. I found the threads to be highly informative and suggest that you read them Keegan. Roger actually contributed to the first thread.

I experienced what I believe to be real honest to goodness misting before on a few occasions and not condensation being showered down on me due to rain strike. It is of course possible for these two events (misting and condensation showereing) to occur both in concert and separately as far as I am concerned.
I have yet to try the silnylon treatment I posted the link to. Others have reported success with the method and I plan on trying it soon since the weather has broken and I can safely apply the treatment and let it dry in the outdoors now.

[EndoftheTrail]

Question for OP, Jeff and other folks who have experienced genuine misting from pounding rain (and not from rain knocking down condensation droplets): how bad is it?

I've never experienced misting from pounding rain — although I am well aware that it can happen. I'd like to know how bad it gets. Does it really soak your bag and gear? And when I say soak, I mean wet to the insulation — and not just the shell material.

If I guess correctly that "misting" is more annoying than actually bad (meaning soaking your bag) — then maybe coating and waterproofing the silnylon isn't really necessary — for two reasons:

1. This adds weight to the material — and defeats at least partially the purpose of moving away from coated nylon.

2. Coating will make the silnylon even less permeable — and thus potentially encouraging even more condensation coating. And when rain hits and knocks off those condensation droplets — it's the same darn effect as misting — if not even worse!?!

So, I am curious as to folk's actual experience with misting — how bad? How often?

[Lynn Tramper]

I don't know how common "misting" is, but I just carry a 3oz bivy bag with me at all times. If wet stuff is falling onto me (for whatever reason) I just get in my bivy bag and don't worry about it.

[David Ure]

Hi Lynn – which Bivvy Bag?

[Keegan Wagner]

Benjamin, what It did to me was it did get the shell material of my bivy(breathable nylon) wet. My bag's shell was a little damp but not bad. Oh and about the adding diluted silicon to the tarp, I've done this before to seam seal and afterwards it was sticky. Wouldn't my tarp be sticky after drying if I did this? Correct me if wrong
Thanks!

[Travis Leanna]

Keegan,
If you let the silicone dry completely, it should not be sticky. It will be much less slippery than the silnylon–even grippy against some fabrics–but not sticky. When I think "sticky," I imagine it still in its liquid state. Make sure you can let it dry overnight to be sure.

[Keegan Wagner]

Yes I let it dry overnight(seams)and they weren't "sticky" but were tacky(grippy). this is the reason why I think some people put it on the floors of tents and, so they won't slide

[EndoftheTrail]

Keegan:

If just your bag's shell material got damp "but not bad" and the insulation inside was all fine — I would suggest asking around (like I have up above) just how bad this misting can get. Because if — as I suspect but don't really know for sure — misting doesn't get very bad beyond 'annoying' — it may not be all that worthwhile to coat the entire underside of your silnylon as that adds more weight and eliminate entirely the fabric's air permeability (what little there is). This, in turn, may exacerbate internal condensation…

[Lynn Tramper]

"Hi Lynn – which Bivvy Bag?"

Home made cuben bottom/momentum top. It's a bit academic now that I've got an entirely cuben down quilt.

I agree that silicone coating makes the fabric tacky, but you can dust it with talcum powder to minimize the tackiness. I kinda agree with Ben that it may not be worth it if it's only occasional misting just making things a little damp.

[Jeffrey Kuchera]

Ben the misting that I exfperienced was not that bad. It was more of an annoyance for me than an actual problem resulting in wet gear as you correctly hypothesized. However, it was annoying enough that I would be willing to take the two or three ounce hit in the application of silicone to my shelter. It is also worth mentioning that I do not carry a bivy sack (I just can't do the bivy thing I find them too restrictive) and that I use down sleeping bags. If two or three ounces of weight gained during the application of additional silicone to my shelter can stop it from misting then I am all in. Any real threat is minimal but the peace of mind afforded by the additional coating is worth quite a good bit when measured in the sound sleep and lack of misting that would be provided.

[Jeffrey Kuchera]

Posted by Ben Tang -"Coating will make the silnylon even less permeable — and thus potentially encouraging even more condensation coating. And when rain hits and knocks off those condensation droplets — it's the same darn effect as misting — if not even worse!?!"

Ben I am not really sure that rendering silnylon less permeable and thus more susceptible to condensation is really a problem. So we shall suppose that we are dealing with a shelter that has been doused with extra silicone treatment. Let us examine the first scenario in which no rain is falling. If it is not raining it is less likely that your shelter will gather condensation in the first place. Even if your shelter gathers condensation there will be no rain strike to knock the condensation down on you. No harm no foul in scenario one. In the second scenario let us suppose that it is indeed raining. Condensation will probably be more likely to form in your shelter since it is raining. Rainstrike will likely knock the condensation down onto you. Real misting may occur. Rainstrike condensation showering and real misting may occur in concert or independently of one another. But remember it is raining! Even if the added silicone treatment rendered the fabric less permeable where would the condensation have gone anyway assuming the fabric was not treated with additional silicone and thus more permeable? Think about this and remember that it is raining. The condensation would not have moved from an area of presumably lower humidity inside the shelter thru the shelter fabric to an area with higher humidity outside by the route of a mostly wetted out fabric barrier. It is raining. So I think your concern in reference to loss of permeability is unfounded.

Let me know if I am missing a piece of the puzzle.

Peace and trail grease, -Jeff
edited for spelling

[EndoftheTrail]

I was trying to say two things (maybe not all that well).

Firstly, that applying a coating probably wouldn't be worth the effort and the added weight. Say the coating succeeds in stopping outside rain from piercing through. That just eliminates one of two causes for misting. It will do nothing to stop misting from rain dislodging condensation droplets. This, we both agree.

Secondly, I also think that by coating and eliminating what little permeability the silnylon fabric has — the shelter "may" be even more prone to condensation. Why? I compare this to wearing a permeable windshirt vs. a coated wp/nb rain jacket. While the permeable windshirt can wet out from the inside by perspiration, it will do so at a slower rate than a coated wp/nb jacket — everything else being equal. Now just how much this effect has on a shelter — I don't really know.

I am still curious from other users about their "misting" experience — is this really a big deal or not? Where's everybody??

[Jeffrey Kuchera]

I read you better now Ben. I though you were really concerned about the loss of permeability. It is clear adding the silicone treatment would add weight to the shelter and do absolutely nothing to prevent condensation showering from rainstrike. We are in agreement there. I would safely say that we are also in agreement that an additional silicone treatment would reduce the permeability of silnylon. However, as I previously stated I feel that the loss of permeability would really be a non issue. Some other input would be nice as it seems we are bouncing the ball back and forth on the playground all alone at this point!

[EndoftheTrail]

Just to beat the horse a bit more…

As an aside — If you currently roll your tarptent and stuff the resulting loaf into its stuff sack — you should know that when you try to do the same after coating the fabric — your tarptent will balloon out toward the end — making it quite annoying to wrestle into the stuff sack. You will have to make sure to expose some mesh parts first so that air can be pushed out as you finish rolling.

[Lynn Tramper]

I find we get the most condensation when it is cold outside and no wind blowing. Usually when it's raining the temp difference between inside and outside is not as great, so condensation is not as big a problem in the rain as in the cold, even if it's a dry cold.

Methinks the air permeability of silnylon is so low that coating it won't make much difference to condensation, but that's just a hunch.

[Jeffrey Kuchera]

I was kind of getting ready to lead discussion where your very last point just went Lynn. I also don't think silnylon is very permeable anyway. I have an silnylon squall anorak from equinox gear and let me tell you it is like wearing a garbage bag.

[EndoftheTrail]

As mentioned, I don't know the exact effect. But as alluded to above, when you can easily roll up your tarptent without the fabric ballooning out — that's permeability right there.

[Jeffrey Kuchera]

Ben, Again I agree that coating with additional silicone will reduce permeability. I had agreed a couple posts back and in fact I had never disagreed on this point. I am not really sure that the reduction in permeabiltiy is a problem though. Plain and simple, my point is that I don't feel the reduction of permeability is a problem for the reasons I already cited. I also think you are making a mistake in comparing the ability of air under pressure to pass thru a fabric to the ability of moisture not under pressure specifically condensation to pass thru a fabric. Permeability is evidenced in both cases, but it would seem these are two different instances of witnessing permeability. I could be convinced that I am wrong though. Thanks to everyone who has participated in this thread. I have enjoyed the mental jousting and learned a good bit in the process.

edited cause I don't want people thinking naughty thoughts about sandboxes and sandcastles and so forth. My spelling sucks too so I fixed a bunch of mistakes.

[EndoftheTrail]

Ummm, people might misconstrue your last statement. :)

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