This is the best quilting tool I found!
I've used it now on 2 quilts and can't imagine quilting without it. What I did was tape the backing to my floor (I have tiled floors so this was a big help!). I followed the instructions on the can and sprayed. I then laid the batting down and was able to get out all of the lumps and folds. I flipped it over to make sure it was absolutely smoothe. Then I taped it back down again batting side up, sprayed the batting and laid my quilt top down. Smoothed out and then pinned. What a difference then just straight pinning.
There is no gumming of your needle and the spray washes right out. And it also mops up off your floor! I recommend if you have another surface other than tile, put newspaper or craft paper down. There is a lot of overspray.