I just did a lap quilt with the wall method and love it. I have a design wall made with sheet insulation covered with cotton batting. I used large safety pins to cover it with a queen sized sheet and pinned the backing securely so it didn't have a chance to wrinkle. Light spray is key and smoothing each layer well. I let it stay on the wall for overnight so it was completely dry before I started sewing it. I did stich in the ditch with a size 11 needle, Arifil thread, warm and natural cotton batting and there was not one problem. There was some overspray but the sheet did it's job.