I've converted some old MOD goretex waterproofs into an extra-long drybag for my foam mat, and was thinking I could fully waterproof it (rather than just splash proof) if I sealed the seams - this stuff seems to be the way to go; http://www.amazon.co.uk/dp/B000XYUO6I/r ... wo=&hvqmt=

Does anyone know of a better deal? Or any reason why it wouldn't work on goretex?

It'll work fine on Goretex or anything else that isn't silicone coated.