Seam Sealing sil-tarp, inside--ouside--both?

[Big Dawg]

OK, a seach here a WB brings varied scattered info about seam sealing for tarps/tents/sacks, but not enough info to make my final decision. I am making a silnylon tarp soon, & will be using McNett Sil-Net to seam seal, & wanted to know how people seal?

#1. Top side (outside) only
#2. Bottom side (inside) only
#3. Both top & bottom

Also, I realize the ridgeline seam is the most important to seal, but I've also heard/read to seal all seams, including all edges (that are hemmed & sewn),,, is this correct?

Thanks!! :sun

[vipahman]

Top only. Edges that would run along the ground when the tent is staked usually don't need seam sealing.

[Just Jeff]

If you don't seal the edges, the water will leak through the tarp a 1/4" from the edge (or wherever you put your seam). I think losing that last 1/4" is worth the giving up for the weight of seamseal around the entire perimeter! :)

I guess some folks do both sides, but one side is plenty if you do it thick enough.

[Big Dawg]

I guess some folks do both sides, but one side is plenty if you do it thick enough.

In your expert opinion, if applied thick enough, which side is usually the preferred side to apply on?

[stupe]

I used SilNet by McNett to do my tarp, and the tube reads "apply to inside of seam when possible". Thats what I did on my silnylon tarp, and with urethane sealer on my coated nylon tarp. I sealed everywhere there was stitching, even the hems and corner tie out reinforcements. Never had a leak, even in some pouring rains I was in.
I used SilNet full strength, and used an old toothbrush to get the sealent under the edge of the fabric. I smeared it pretty thin.
I dusted the SilNet with talcum powder after it cured, and kept the sealant from sticking when I rolled up the tarp.

[hammock engineer]

It was mentioned in another thread that the seal sealing also helps broken threads. If your thread breaks the seam seal will keep the whole thread from coming out.

I think the extra strength is worth a couple extra ozs.

[vipahman]

In your expert opinion, if applied thick enough, which side is usually the preferred side to apply on?
Don't apply thick. Apply on the outside. But I slept bone-dry in 10 hours of pouring rain, so I wouldn't know, would I?:-?

[mweinstone]

hello my name is troy mclure,you may know me from such training vidios like...seam seal king of seals...or....sealed with a kiss..of glue.today were here to learn how to seam seal.belive it or not their is a science to it.you can learn more from bibler tents at black diamond web sites.the skinny is...only seal lap felled seams on the inside and seal butted seams on the outside,..and loops witch are sewn thru , on both sides.i copyed that from the package of the mcnett sil net you are using.matthewski out.

[Just Jeff]

Haha...I guess there are as many opinions on seamsealing as on how to hem a tarp's edges? Applying sealant to the outside exposes it to UV and more dirt. Applying it to the outside will keep the threads from getting wet at all. Both will keep you dry if done correctly.

Rubbing it with talcum powder will help prevent the dirt (and other stuff) from sticking.

By "thick enough" I meant to make sure it completely covers the thread holes and threads, not thick enough to cause a roly-poly distress as it crawls over the tarp.

But then I've only stayed dry in a few rainstorms, so I don't claim to have the only right answer! :p

[Big Dawg]

Don't apply thick. Apply on the outside. But I slept bone-dry in 10 hours of pouring rain, so I wouldn't know, would I?:-?
Sounds like you do,,,,,,,,,,, already got your answer,, was looking for Jeff's.

Thanks for replying, though.

.

[Whistler]

I like applying on the inside, for aesthetics.
-Mark

[Just Jeff]

It was mentioned in another thread that the seal sealing also helps broken threads. If your thread breaks the seam seal will keep the whole thread from coming out.

I think the extra strength is worth a couple extra ozs.

Makes sense.

Another way to handle this is to backstitch a couple of stitches every foot or so. Then if a stitch pops in the field, it'll only go to the nearest backstitching...should be good enough to get you through to a repair, weigh less than seamsealing the perimeter, and be MUCH less hassle to make. Seam-sealing isn't as bad as working with down, but it's still a PITA!

I don't claim to be an expert, or even to have a lot of experience with homemade gear...plenty of people here have more experience than me and I don't pretend otherwise! I'm just throwing out ideas...no more or less right than anyone else's. Take what you like and leave the rest!

[Roland]

Makes sense.

Another way to handle this is to backstitch a couple of stitches every foot or so. Then if a stitch pops in the field, it'll only go to the nearest backstitching...should be good enough to get you through to a repair, weigh less than seamsealing the perimeter, and be MUCH less hassle to make. Seam-sealing isn't as bad as working with down, but it's still a PITA!

I don't claim to be an expert, or even to have a lot of experience with homemade gear...plenty of people here have more experience than me and I don't pretend otherwise! I'm just throwing out ideas...no more or less right than anyone else's. Take what you like and leave the rest!
My wife and I have made custom stuff sacks, but otherwise don't make much gear. Perhaps someday we'll get more ambitious. Your idea of backstitching is a good one, and one I'll file away for future use. Thanks for the tip.

When I ordered a Tarptent, I picked Henry Shires brain about seam sealing. Besides waterproofing, he suggested that sealing enhances the structural properties of the seam, by bonding the thread and fabric together. It made sense to me, and seems like a lightweight solution to extend the life of the product.

[kanga]

mixed my mcnett's with some mineral spirits and did my felled seams on the inside. perfect coverage on the thread and seems to hold out water nicely but i haven't tested it in a rainstorm yet. for those that have more experience, will one coat do or do i need to do it again? will a double app make it peel?

[Lyle]

Cheaper than Sil-Net and much easier to find locally, is Silicone Windshield Sealer. I got mine at NAPA for a buck. Was enough to seal my Wild Oasis and The One. Make sure you get "flowable" silicone. Easy to apply, has worked great for about a year now, no leaks.

[Tinker]

OK, a seach here a WB brings varied scattered info about seam sealing for tarps/tents/sacks, but not enough info to make my final decision. I am making a silnylon tarp soon, & will be using McNett Sil-Net to seam seal, & wanted to know how people seal?

#1. Top side (outside) only
#2. Bottom side (inside) only
#3. Both top & bottom

Also, I realize the ridgeline seam is the most important to seal, but I've also heard/read to seal all seams, including all edges (that are hemmed & sewn),,, is this correct?

Thanks!! :sun
#1 - Ok
#2 - Ok
#3 - Better
Seal all floor seams. If the upper of the tent is breathable nylon, don't bother sealing between the floor and the breathable nylon.
Don't bother sealing the perimeter seams of the fly.
Applying sealant to the stitching which mates the waterproof material on tent or fly with guyline or stake pullouts will increase the strength of the stitching.
Use talcum powder or your seams will stick like velcro on other coated (impregnated - spelling/usage?) surfaces of tarp or tent.

[Nearly Normal]

http://jwbasecamp.com/Articles/Silnylon1/index.html

This might be helpful.

[buz]

I always do both the inside and the outside of any seam where if rain came in, I would be wet, or pissed it leaked, lol. On edges and non critical rain seams, the outside only. For sure dust with talcum or baby powder. U can use a small paint brush for the powder, simple and fast. So far, I haven't been wet, so I will continue this way.

I think the jw method above is fantastic for sil nylon. I did a 1 to four ratio on my tent floor both inside and out, and it eliminated the need for a ground sheet, and no more slippage inside. I did 1 to 3 for seams.

[kanga]

http://jwbasecamp.com/Articles/Silnylon1/index.html

This might be helpful.

that was perfect! thank you, exactly what i was looking for.

[Nearly Normal]

that was perfect! thank you, exactly what i was looking for.

I can't claim it. The site was posted here before but I don't remember who.
Thanks anyway. :)

[stranger]

Ridgeline = seal both sides
Other seams = seal the outside
Edge seams = not really important

Other note - seam sealing greatly improves the strength of seams, expecially with ultralight materials. I would seal any major stress point very well (while under the tarp is under stress) to prevent any blowouts.

[walkin' wally]

Great thread. I just bought a tarptent, so this is very helpful. Thanks

[mark schofield]

I just unpacked my shires tarptent after a seasons rest. (I should have hung it in the basement). I sealed it when I bought it last year but didn't use the talcum powder. Definitely the powder will help. Also, I read a post by someone suggesting that instead of stripes of silicone on the bathtub floor of some tarp tents, put dots instead. T can see why.