Duravent - How do I seamseal it?

Tyvek - How waterproof is it? I've read something about the different series, and that the ones treated to accept ink for printing aren't as waterproof as other series. Also, some are microperforated. Which types work best for hiking stuff?

How breathable is it? How do I seamseal it? Or is it best to just use the 3M tape?

I'm thinking about using it for a hoodless poncho, so it doesn't really need to be breathable, but it needs to be waterproof and I have to be able to seal the seams.

Thanks in advance for any advice you can offer!

Jeff, Spock here,
I use Barge's cement or Duco household contact cement. Not only can you seal the seams, but you can use these glues instead of stitching. Proper procedure is important: Clean surfaces with alcohol, dry, apply very thin layer of cement to both sides, allow to mostly dry, mate the surfaces, press firmly, pound lightly with rubber hammer.

Spock,

Thanks for the help. Do you use that on Tyvek or Duravent? How long does a seam like that last?

I've never heard of or used Duravent but have tried sewing Tyvek and found out that it really weakens it. It ripped fairly easy where I sewed it. I made a simple tent out of it and it didn't last more than one good windstorm. Good luck with your results.

I'm mainly thinking about using it for prototyping so the strength isn't all that important. But my first project is a hoodless poncho, and the only seams will be around the neckline so I don't want them to leak.

But I haven't gotten a straight answer on whether or not it's actually waterproof! I guess it'll be waterproof enough for a few prototypes, though.

Duravent is microporous polypropylene...I've been thinking about a hammock bivy for a while now.

How long do glued seams stay waterproof? As long as they last. That is just about forever if they are not melted by DEET or gasoline.

How strong are glued seams? Stronger than Tyvek.

I don't have any experience with Duravent.