View Full Version : I've failed seam sealing--help!

02-19-2003, 13:10
I've just finished making a some silnylon stuff sacks and used SilNet to seal the seams. I then tried to inflate the stuff sacks (ala Jardine's beachball description) and while each inflated, they lost air fairly quickly.

I know this can't be THAT technical, so what am I doing wrong? Here's what I did, any new techniques would be appreciated.

I cleaned the seams with alcohol (from the medicine cabinet).

I let it dry.

I squished out some SilNet onto the seam on the OUTSIDE of the bag, and pushed it around, trying to "push" it into the seams, as Jardine described. I squished more, until it covered an area maybe 1/4 inch on either side of the seam (on the OUTSIDE of the bag), and seemed to be a consistently thick layer right over the seam. It doesn't "glob" over the seam.

I let the whole thing dry for 24 hours. Then I tried the beachball test and failed. :-(

I have filled the sink with water, and found that there is no consistency to where the leaks are, it's not just the corners, nor is it the whole length of the seam.

Any words of wisdom for the next batch I try to seam seal? And, I'm assuming I can just put a little more alcohol on the leaky bags, and then more Silnet, but again, any suggestions would be helpful.

I'm sorry if this is a really stupid question... you should have seen me paint a wall the first time. Sheeesh.


Blue Jay
02-19-2003, 13:37
This is not a stupid question, seam sealing is hard to do. Try two thin layers of sealant without alcohol in between. Everything else you are doing sounds correct. On a positive note, once you get them sealed it seems to last a long time

02-19-2003, 15:28
Beth, I made a few silnylon bags and mine held water with no problem. This is what I did.

1) Turn the bag inside out
2) place the bag flat... put on a THIN coat of silNet on the stiching and work it in with your fingers. Don't worry if it looks a little uneven, it settles itself out.
3) Wait 24 hours, flip the bag ove and do the other side.
4) I am not sure how yours is sewn, but at the bottom make sure you get the corners well
5) Wait another 24 hours, and test the bag
6) any small leaks or beading just mark the spot and touch up.

I made 5 of these bag and all mine can hold water... It too a lot of patients... so when one was drying I was making another on the sewing maching.


mvng mtn
02-19-2003, 17:19
When I need to seam seal anything, I use a plastic syringe with a curved tip(it does not have a needle): a Monoject 412 syringe. You can get them from a Vet, Dentist or from Black Diamond for about a $1( I got a couple from my Dentist for free). I put in the sealer and put a line of sealer down the seam and then go back and work it in with the tip of the syringe. Pretty easy with little mess. Seems to work with any kind of sealant.

02-20-2003, 18:31
Thanks for the ideas. I shall give them a try!

You'll recognize me on the trail. I'll be the one playing beachball with my stuff sacks.

Thanks. Beth

02-22-2003, 05:31
Another thing to think about is to stop wasting time sealing your stuff sacks and just buy some pre-sealed sacks, as this issue is a bit humorous considering the time it can take to seam seal items. Time = Money. Just a thought. Cheers!

03-07-2003, 16:07
Does anyone even make sealed Silicone-Nylon stuff sacks?

03-07-2003, 16:10
I buy ditty bags at campmor for like $2, seam seal them myself, and then resell them for about $5. It doesnt take that long when u know what your doing. ANd tlb...i dont think so. Exped makes some nice drybad type bags- ive got 2. They are not silnylon. But my 850 oz. clothing bag weighs only 4 oz!


Rhody Bill
03-07-2003, 22:20
Stephenson's ( Warmlite) recommends using Silicone II thinned with mineral spirits (paint thinner) for their silnylon products. ( It doesn't really "thin" it , it's more like a suspension that eases spreading) . Poppa Smurf ('00 ) bought one of their tents for our '01 Long Trail jaunt and we sealed it following their directions. He had no problems. I sealed my homemade silnylon tent on the inside and outside with Silnet which I had bought when I got the material. Both sealing methods seemed to work fine, the Silicone II being more readily available. (Stephenson's website I believe has the instructions). I also found that stripes of silnet (very thin) accross the floor of my tent prevented most of the sliding around that happens with silnylon.