I have noticed the 8 oz. poly from Dyson to slacken slightly, but I too think it is due to temp, not moisture as with nylon. When I skinned my last boat with the polyester, it remained tight until temps were drastically cooler; it tightens back up if left in the sun for a while... Now, it is not so slack that it looks wrinkled as I have experienced with other fabrics, it is just not "drum tight." I've got another frame ready to skin, and now that it is cooler, I'll have to see if the temp theory is correct.

: I tried Polyester this time. 15 oz, shrunk on the boat. Oil based paint.
: Looks good. Now I am noticing it is getting loose. I was under in the
: impression that polyester wouldn't do that. I know it didn't go loose on
: the water like nylon. So what am I missing? Why has this one loosened up
: sitting in the garage? Does the temperature effect it? We are having our
: first cooler weather.