I have used the June Tailor basting spray on both poly and cotton. It was great on both battings, buy I found working with poly was easier. Just be sure not to stretch your batting as you lay it over the back. I think that is what I did on my last baby quilt and when the batting went back to normal it was stuck to the backing and the backing was wrinkled. The good thing though, is that I could pull the backing loose, smooth it out and it would restick. I use pins around the edges.