I love the spray basting. It allows you to have a very taught sandwich, much like the long arm quilters. I have found that after spraying the backing (wrong side of fabric) it is best to use masking tape and secure it to the floor so that it is taught. Then place the batting on top of the backing. I spray my batting or fabric in the garage or outside if it's not windy or cold. I have sprayed either fabric or batting and not found a difference. After smoothing out the batting on top of the backing fabric, I spray the back of my quilt top. Sometimes it is helpful to have a friend take two corners and you hold onto two corners as you transport the fabric that has been sprayed, that way you avoid the inevitable flipping that occurs and the need to pull it back apart, possibly stretching something. I usually find it helpful to lightly press the sandwich and pull everything taught and remove any bubbles. I do this from the top first, before removing the masking tape around the perimeter of the backing attaching it to the floor. Then I flip it over and make sure the backing is taught, pressing it. Remember, to spray lightly, check with your hand to feel tackiness, you won't be able to see it.