It has to be washable school glue....the generic brands work too. I drizzle thin lines of glue about 3 to 4 inches apart in kind of a grid, straight from the bottle, onto the batting. Then spread out the top, smoothing and patting down. After it air dries for about an hour, I flip and repeat the process to glue down the backing. If I get a blob of glue just smooth out with your finger. Cleanup is just a damp washrag! Be sure to let the sandwich dry completely before quilting....either air dry or speed up the processusing a dry iron. And now is the perfect time to stock up on glue at the back to school sales! I never have any shifting or wrinkles, nor do I have to pin the edges. When the quilting/binding is done I simply wash with detergent in warm water.