Seam sealing RBTR silpoly

**Titaniumpyro** · 01-06-2015, 18:48

Well, my latest tests are fully cured. First was to directly compare the bonding of one side vs the other.
One side does peel off easier than the other but both sides do still come off, with Flowable Permatex, GE Sil II and Silnet, with Silnet being the one that holds on the best, relative speaking. It still comes off just takes a little more effort. Second test was to try all 3 on the coated side of a PU tarp.
As expected, all 3 peel off with the Silnet sticking the best.
So if one side is coated with Silicone perhaps it is coated first and there is enough excess on the rollers
That the silicone side is "second coated" with the Sil/PU
Whatever the cause, if we can figure out a seam sealer that sticks then this Silpoly will be great stuff.
It is much easier to work with, doesn't stretch or slide all over the place and it doesn't have that slippery feeling
that Silnylon has. In fact it doesn't really feel like there is any coating at all.
Looks like I will have to order the Sea to Summit product so it may be next week before I know anything on that front.

**ripstopbytheroll** · 01-06-2015, 22:02

Originally Posted by Titaniumpyro

Well, my latest tests are fully cured. First was to directly compare the bonding of one side vs the other.
One side does peel off easier than the other but both sides do still come off, with Flowable Permatex, GE Sil II and Silnet, with Silnet being the one that holds on the best, relative speaking. It still comes off just takes a little more effort. Second test was to try all 3 on the coated side of a PU tarp.
As expected, all 3 peel off with the Silnet sticking the best.
So if one side is coated with Silicone perhaps it is coated first and there is enough excess on the rollers
That the silicone side is "second coated" with the Sil/PU
Whatever the cause, if we can figure out a seam sealer that sticks then this Silpoly will be great stuff.
It is much easier to work with, doesn't stretch or slide all over the place and it doesn't have that slippery feeling
that Silnylon has. In fact it doesn't really feel like there is any coating at all.
Looks like I will have to order the Sea to Summit product so it may be next week before I know anything on that front.

Thanks for reporting back. I will pick some of that up ASAP as well as look into finding something similar. From the looks of that product it's just something they've put their brand name on, so it's probably available elsewhere, but in the short term if that works, let's use it. I will also make a note on the website with suggestions on seam sealing for those making tarps.

I think at this point it would be best if we could move all this info to another thread e.g. "Seam sealing RBTR silpoly" and put it in DIY. That will make it easier for people to find the info and free up this thread for build pics. Can we do that mods?

**Boston** · 01-07-2015, 06:53

Since everyone has tried most of the normal silicone sealer's, it may be reasonable to try the PU sealer's also, just to see. Since the silicone wont stick, would something like SEAMGRIP work due to the PU content? Might be worth experimenting with also, if anyone has some laying around.

**sr1355** · 01-07-2015, 10:24

I just happen to have a tube of Seam Grip, a PU sealant. I also happen to have a sample of SilPOLY so I just applied a bit of Sea, Grip to both sides and will report tomorrow after it has cured for 24 hr. Not sure if anyone has tried this yet...

**sr1355** · 01-07-2015, 10:40

I also have applied our 100% silicon sealant to both sides of a sample to see if there is any difference in holding power once cured.

**sr1355** · 01-08-2015, 13:49

RESULTS ARE IN:

I had the best results with 100% silicon. On one side of the fabric both the silicon and seam grip peeled right off with minor effort. On the other side of the fabric I achieved better results with both of them adhering well. The 100% silicon appearing to bond the best and I could not get it to flake or peel. These were cured under light pressure, i.e. ream of paper on sealed area stacked on a piece of glass.

Without clearly knowing which side is which on the fabric I can not say as to which finish it adhered best to.

**Freakin Farmer** · 01-08-2015, 14:41

Good info, thanks for passing it on. I am a first-timer when it comes to crafting tarps. Saying I built mine with the "wrong" side out, would sealing it from the under side be effective?

**Boston** · 01-08-2015, 14:50

Yes, actually that's usually what people do (seal the inside of the tarp).

**Freakin Farmer** · 01-08-2015, 14:54

Oh, ok. Good to know. haha So flip the question, what if I had to seal on the outside. Effective?

**squidbilly** · 01-08-2015, 15:55

Sealing the outside is effective too. That's what I've always done. But that was with silnylon and argon: no problems with Silnet or Permatex adhering to those fabrics.