How much ,if any, does sil-nylon lose its waterproof characteristics over time. I have an older TT Rainbow, first or second year of manufacture. It seemed to be either misting or heavy condensation the last time I used it. This was in the PNW near water and kind of cold rain conditions. It was seam sealed soon after purchase. I've used the tent a lot over the years but it has always been taken care of; dried after each use, not left all day in the sun, etc. I'm thinking of selling it (replaced with a SMD Starscape) but I don't want to put a bad tent out there. Thanks.