: I just used the baking paper release and it helped but if I blew it up by
: lung power they would blow seam or leak though the melt. I would not spend
: money them agin. I have not contacted Outdoor Fabrics for any support.
: Don

Must be the material used then. I have made a dozen dry bags over the years and the only times they weren't air tight is when I mucked up the seam. No way could the seam blow out since its as strong as the material. Please don't ask me the name of the stuff, I just got what looked right. "Heat sealable fabric" draws blank looks at the suppliers here. The material to use is heavily plastised right through the canvas on both sides. One side is only slightly less shiny then the other. Use the shiny side as the inside of your seams. Take a look at some heavy duty dry bags in the shops to get an idea. Most air bags and cheaper dry bags are made from the same material as paddle floats. I do not think this fabric will heat seal very well.

I did try a material once which had nylon fabric on one side and a rubber/plastic coating on the other (like some cheap spray jackets) and had the seams blew out. Stitching helped but of course it would not be air / water proof then.

Take a break then give it another go. For dry bags the cost of home made was only $10NZ (approx $5US) each, less then 1/4 the price of a brought bag. The price of new air bags here will make you gasp for breath! Approach a local upholster for offcuts of different material to experiment with. Or try a glue for the seams.

Experimenting is the only way to learn and I bet that if you had to buy a third lot of material, it will still work out cheaper then buying new.

Cheers
Grant