I too use washable school glue. It's economical and tidy. Hold the bottle about 6-8 inches above the batting so you get a thin stream and move the stream in a zig zag fashion. It will bead up. You don't need much. Smooth the backing over the batting with your hand. Let dry. Flip over and repeat for the top. Put the glue on the batting and not the fabric so it doesn't soak through. Wash quilt with warm water to get the glue out.