Wing project is almost done and I really like it. I took 1000 Denier Cordura and coated it with a layer of AquaSeal (I use 8 oz tubes - much cheaper). Then sewed the wing 7/8 the way around, turned it inside out and AquaSealed the seams. Turned it right side out and put the OPV and LPI holes in the bladder, sewed it closed and used the back hole to use a finger to AguaSeal the last stitching. Then apply AquaSeal between the fabric at the edges making sure to get the stitching and let cure under weights. Make sure to talc the freshly cured AquaSeal otherwise it bonds to itself. Sew a binding around the edge and then set the grommets. I have done all but the grommets and pressure tested it. It feels as heavy as the commercial ones and holds air well. The "seal the perimeter stitching from inside" step probably isn't needed, but given physics, should make it very durable.
Thinning the AquaSeal with Toluene helps spread it better. Other thinners might work, but I know Toluene does and still have a supply at home.
If making a donut wing: you can probably seal all the seams from the outside. This just leaves visible AquaSeal on the finished project. I have used this technique on my back up perimeter seams on my heat sealed versions and it holds well. I have even coated the entire outside of a (heat sealed) bladder with AquaSeal when the inside coating started to wear. This bladder has about 100 good dives on it.
You can start with a completely airtight fabric (reinforced PVC) or heavily PU coated fabric) and skip the coating step, but I worked with what I had on hand.
The 500 D heat sealed fabric works well as an inner bladder in a casing. I don't think it is durable enough to use as a single layer, hence my further experimentation. 500 D heat sealable packcloth is available at
www.seattlefabrics.com as well as 1000 D Cordura or even Ballistics cloth. AquaSeal 8 oz tubes are available online for about $20, or you might even get your LDS to order you a tube. Keep it in the freezer between uses.
Have fun and happy creating.
