I overkill it. I spray baste and pin. I work on my ironing surface the way you would iron a sheet. I put the batting down and then iron and spray in sections the front to the batting. Any excess spray lands on the batting. Then I trim the batting to the front, flip and iron and spray the backing. Once it's a sprayed sandwich, I go back and pin about 12 inches apart. I have a Juki 2010. I have found that the pinning helps hold it all together from the tugging and pulling thru the machine.