Hi, I am having issues with wrinkles after sizing a muslin flat. Details: 4' x 8' 2x4 frame. Muslin glued to frame and outside edges, left the muslin slightly loose (just touching floor in the center when laid down). After it dried to the frame, we sized with 50-50 glue (Elmers' white school glue) and water mixture. Tightened up during application, but then dried wrinkled. I thought the kids (HS students) just didn't saturated the flat enough, so I resized. Dried wrinkled. Anyone know why this happened? Can I fix this without starting over?