Seam sealing tarp ridgeline

**rais'n hammock** · 08-10-2015, 20:42

I finished my silpoly tarp and sealed the ridgeline from the outside. I noticed RSBTR posted a new instruction for DIY tarp's and state to seal from the bottom side.
I asked the question but it may be lost in the thread so I am asking again.
Is there a reason the seam should be sealed from the bottom other than cosmetic. I would think that the seam sealing on top would stop the water from entering the seam and avoid issues of water being trapped and possibly causing mildew. This is more likely an issue for tieouts but still can happen on the ridge.

What do you do and why?

**SilvrSurfr** · 08-10-2015, 21:26

It never occurred to me to seal from the top. I've always sealed from the bottom.

I don't think you have to worry about mildew, if you properly dry your tarp out.

**ksbcrocks** · 08-11-2015, 07:19

I like doing it from the outside. I'd rather keep the water out completely. I'm pretty sure doing it on the inside is just for a better looking tarp on the outside.

**rais'n hammock** · 08-11-2015, 07:22

Originally Posted by SilvrSurfr

It never occurred to me to seal from the top. I've always sealed from the bottom.

I don't think you have to worry about mildew, if you properly dry your tarp out.

Do you see any disadvantages to sealing the top? I understand the proper drying but still wanted to avoid water even entering the tieouts reinforcements.
Why did you choose to seal the bottom and not the top?

**dudeman_atl** · 08-11-2015, 07:23

I sealed my silpoly from the outside and it wasn't enough. Sealing it from the inside did the job.

**Firesong** · 08-11-2015, 07:35

I seal both sides when making the tarps. The other thing is some fabrics have a top and bottom so there may be a technical reason for it as well. With the sil poly one side is a silpu mix and the other is a pu coat.

**Monkeyboy42** · 08-11-2015, 08:53

Originally Posted by Firesong

I seal both sides when making the tarps. The other thing is some fabrics have a top and bottom so there may be a technical reason for it as well. With the sil poly one side is a silpu mix and the other is a pu coat.

This was the first gen of silpoly that had two separate sides. It also had seam sealing issues in general. Second gen silpoly has no difference between the sides. I sealed mine on the outside, and it's kept me dry through a number of substantial downpours. I'm fairly certain that this is an aesthetic suggestion.

I actually read and watched some tutorials that suggested pitching the tarp properly, so that the sewn through stitch holes will stretch open under their real world use, and then seal the outside, so that the sealant can flow into the holes. This makes more sense to me then sealing the inside.

**rais'n hammock** · 08-11-2015, 09:02

Originally Posted by Monkeyboy42

This was the first gen of silpoly that had two separate sides. It also had seam sealing issues in general. Second gen silpoly has no difference between the sides. I sealed mine on the outside, and it's kept me dry through a number of substantial downpours. I'm fairly certain that this is an aesthetic suggestion.

I actually read and watched some tutorials that suggested pitching the tarp properly, so that the sewn through stitch holes will stretch open under their real world use, and then seal the outside, so that the sealant can flow into the holes. This makes more sense to me then sealing the inside.

I used the 2nd Gen Silpoly and this exactly how I sealed it. Pitched tight and applied the sealant on the outside.