I'm making (well, sourcing, since I just purchased the material and had a friend sew it) a tarp for a friend. Pretty simple design, two 5 x 8 pieces of polyurethane coated ripstop (70D I believe). I used my homemade seam sealer (silicone caulk + mineral spirits) down the seam yesterday, but today it's still tacky. I haven't put one of these together since summer, and my apartment is much cooler (not to mention it's been raining nonstop), last couple times it seemed to dry within a few hours. Also wanted to make sure it would still work on this fabric, and if not, what I should use instead.