: fabrics and came across seattlefabrics.com, which sells a marine-grade
: cordura-type polyester (600x600) called Sur Last (then I found
: surlast.com). Is this the type of fabric I should be looking for

Watch out for fabrics from sources that supply outdoor gear enthusiasts. They tend to get coated fabrics (coating usually urethane). These coatings will interfere with the adhesion of the coatings you want to use. What you want is an uncoated fabric.

Mike