I mist the batting (poly and cotton) with water. I don't make it wet, just mist with a spray bottle. Then I mist the inside of the dryer, load in the batting and put it on low heat and tumble for about 30 minutes. About half into the time I pull the batting out, fluff it around a bit, give it a good mist, and back in for the rest of the time.
While it is still warm, I lay it out as best I can and smooth it out and let it cool for about 10 minutes.