I built myself three 4 ft x 6 ft gobos, each made from a framed piece of ¾ inch plywood, a layer of 1/8 inch high-mass vinyl, and three 2x4 batts of acoustical/fire rockwool. Each batt is wrapped first in light tracing paper to keep fibers in, then all the batts are wrapped in theatrical polyester muslin fabric, which is durable and fire-resistant, if not entirely acoustically transparent. I glued the batts to the high-mass vinyl using either Scotch 77 spray adhesive or Scotch 90 (rubber and vinyl). It was several years ago, so I just don't remember. In any event, two of the three gobos have remained glued just dandy. The third has not. The batts started pulling away from the vinyl, so I tried regluing it using Scotch 77. I was pretty liberal applying the spray adhesive and gave it a few minutes to get tacky before I put the batts in the frame and glued them to the vinyl. That lasted only a short while before it started coming off again. This time I tried a good bit of Scotch 90, but that hardly lasted a day or two. I'm not sure how to get these batts to stick. At this point, I'm afraid there's a lot of old glue goo that might be working against adhesion, but it's going to be very hard to remove it. I might be able to reverse the muslin so there is less glue on it, but I do not have access to more of this muslin, so I can't just get another piece. Anyone have any suggestions? Thanks!