I saw some ultralight/ultracheap posts and thought about making a bivy. I have like 7 polycro ground cloths around, and 8 yards of .75 oz plain ripstop nylon

I was going to make a kite, took forever to find the stuff, but anyway...

How would one connect the polycro to the nylon in such a way that it won't just rip apart. Specific seam? glue?? what kind???

Thanks, - Gabe

Gabe,

I have thought about trying some of that kite nylon for some projects. Can you verify it's weight in any way? If you can put on a scale, do this calculation:

total weight of material / (# of yards * width of material / 36)

That should give the weight per sq.yd.

GG's polycryo groundsheets are polyolefin plastic, which is very difficult to glue, along with polyethylene and polypropolene. You can google "polyolefin glue" or adhesive and find some companies that manufacture glue that will work, but probably difficult to get your hands on. You could call 3M and ask them what product to order.

Heat shrink window insulation is polycryo. It usually comes with a double sided tape for sticking the insulation to the window frame. It wouldn't be super strong because it's intended to come off in the spring --probably good enough for a bivy but definitely not strong enough for a tarp or tent.
Is your nylon silnylon?

I had one but it died recently... So I have been using this ridiculous inaccurate analog bread scale. Hmmf.
I haven't bought a new digital one yet and doubt I will before I leave in two weeks.
The cloth I acquired is this stuff:
http://www.sailmakerssupply.com/prod_detail_list/38
And I got it for a whole lot less than 12$ a yard. sheesh...
.75 oz I know some nylon is coated with resins to make them more windproof. I'll try to get that weighed.
It is likely impregnated or coated with something for windproofing, and would likely not be dissimilar to momentum. I just happen to have a lot of it. Wondering what kind of seams, tape, glue would hold it to polycro.