Michael
I'd look into what Hank said if I was you. I painted cordura last year and when it dried I had 80 grit sandpaper. It went from soft flexible fabric to starched stiff sandpaper. I was okay with the sheet good stiffness but the abrasiveness was going to cause problems wherever there was contact with other things like fiberglass and plywood. I ended up redoing the job and tossed the painted stuff. From what others say it works fine on canvas, but I'm suspect of cordura. It might have been the fact the cordura I painted was old and faded with loose fibers that became grit when paint hardened, but before you paint a lot of cordura and spend the time and money I'd at least like to point out the difficulty I ran into.