Seam Sealing Techniques

[Monty E]

I’m the new owner of a Stratospire 2 and I would appreciate feedback on the advantages/disadvantages for different techniques to seam-seal Silnylon. My previous double wall shelter did not require seam-sealing and more recently I’ve been using a taped cuben tarp for most of my outings, so I have zero experience with seam sealing silnylon.

Based on postings on this and other forums, I gather that after diluting silnet or other silicon based sealant with mineral spirits I can do one of the following:

1) neatly apply diluted solution with a fine brush a la Franco’s video:
http://www.youtube.com/watch?v=mYjOkxR4sgc

2) sloppily and more thoroughly apply solution across seams and then wipe excess with towel. This is what’s demonstrated in the Tarptent video:
http://www.tarptent.com/ttvideos.html#seamseal

3) or, neatly apply sealant solution to the threads using a fine syringe (I saw this in a BPL posts).

So what are the advantages/disadvantages for each approach based on ability to keep water out, strengthen the seams, and the overall aesthetics of the final product. Everyone seems to have their preferred approach but Ive found no discussion as to why one approach is better or worse than another. I can certainly speculate on each. I suspect Tarptent’s approach would do fine job at sealing and strengthening the seams which is a plus, but how does the final product look? Or, does the solution simply integrate into the fabric so that the techniques doesn’t really matter all that much?

[Jerry Adams]

Solution integrates into (or onto) the fabric so it doesn't matter

If you "scrub" it a little with the brush the solution will thoroughly wet threads and get into holes

I don't bother sealing my seams on silnylon – never noticed any leaks – but I'm in the minority on this

[Stuart R]

3) neatly apply sealant solution to the threads using a fine syringe

If the syringe is too fine, you won't get any solution out. Perhaps the type of syringe sold with inkjet refill kits?

I had good results with Permatex Flowable Silicon Sealant as it is a not-too-thick solution right out of the tube.

[Franco Darioli]

Monty
For a start "other silicon based sealant " is sometime the problem…
You need 100% silicone not a tube that contains some or mostly silicone.
The Ge II sold by TT is one type, here in Melbourne (for Aussie readers…) I use the Selleys Roof and Gutter (translucent) silicone.
Out of a range of a dozen or so silicone based products, that one is the only one that is 100% silicone.
(it says so on the label…)
A syringe is what I mostly use in spite of what you see in my video.
The reason I do that is because I used to do Bibler tents that way (the syringe was supplied…) and I have more control that way.
The reason I use a brush in my video is because I can also do that and usually it is easier/cheaper to find than a plastic syringe.
BTW, the ones with a bent tip work better.

Franco

[Roger Caffin]

Works very well for me:
100% silicone, such as Flowable Permatex Windscreen or McNett.
Dilution is not needed with the flowable silicones in my experience.
A large hypodermic syringe controls the flow, the spread of the mess, and gets the stuff into the stitch holes.
Press in with finger after applying.

Caution: thin layers of some cartridge silicones can peel off silnylon after a year or two. Not all do really bond properly. I don't know why.

Cheers

[Brad Walker]

+1 on the Permatex flowable. It comes with a tip/nozzle as well IIRC which can be reused if you clean it out (easy to do after the silicone cures).

I dispensed the Permatex along the seam to be sealed, then used a piece of coated paperboard (kind of like a glossy business card) to slide/wipe along the seam. It seamed (:p) do do a pretty good job at both pushing the sealant into the threads and picking up the excess. Start with a small section to dial in the amount to dispense and you will barely have any excess to wipe up.

I've bought some foam brushes to try next time, but I haven't had to seal anything in a while.

[Ken Thompson]

+1 on the Permatex flowable. It comes with a tip/nozzle as well IIRC which can be reused if you clean it out (easy to do after the silicone cures).

+2 Inexpensive, readily available, easy to use, no stink. I used less than half a tube on a Duomid.

[Roger Caffin]

A tip for those still considering this.

When I have finished applying sealant along all the seams I pull the plunger out of the hypodermic, remove any excess sealant as much as possible, and then let all the remaining sealant set in place.

Guess what?
Silicone sealant does NOT stick to modern PE hypodermic syringes, nor to the (nitrile?) rubber bush on the plunger. So once the sealant has dried, I can peel it ALL off easily and have a clean hypodernmic for next time.

Cheers

[Monty E]

Thanks everyone for all the feedback.

Well, it sounds like the syringe method applied to the threads fares well for most. Im surprised that the seam itself does not need sealing, after all it is called "seam sealing". But if this minimalist method works, so be it.

I have some McNett silnet on hand so Ill plan on using it with the syringe methods. Thanks again.

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