June 30, 2016. ESF intern Tyler placing logs on edges of black poly tarp on mowed Phragmites. The two 20×30-ft. black-poly tarps were taped together using “tarp tape.” But within a few hours of laying them out in the bright sun and securing the edges using logs, the adhesive on the tape softened and the tarps separated from each other by a couple of feet. These are 6.0 ounce black poly tarps, waterproof, mildew proof, tear and acid resistant. They have an 11-12 mil thick, 14×14 weave count.