Waterproof stitching?

[Mortblanc]

(22 March 2013, 13:52)Scythe13 Wrote: I'll let you all in on one of the things I'm trying to do with this:

Aside from modify a few waterproofs, I want to set a mylar blanket into the underside of a tarp, for colder weather camping.

So, I need to be able to fold the tarp back up into it's small bag.

Been there, done that. It won't work.

The mylar tears along the stitch lines. I even tried sandwiching it between layers like a quilt. It still tore when stressed.

The fabric has more give than the mylar causing the seperation into sections.

The best setup I achieved was using a USGI poncho with poncho liner and one of the heavy weave reinforced "space blankets" tied into the matching gromets between the poncho and liner.

It soaks you with condensation within minutes.

As far as sealing normal seams??

The first response after the querry was spot on. Seam sealer was invented to (???guess what???) seal seams.