I have made a few of the denim rag quilts. Just to make sure I was sewing it correctly, I made a small 2ft x 2ft mini quilt. I put it by the washer and it went in with the towel washer/dryer loads for a couple of weeks to see how it "fluffed". The dog claimed it after my experiment. So, my suggestion is make a litte one out of scraps and see what happens. Hugs!
PS Dont forget to clean out the lint trap during the first couple of dryer runs. I set a timer for every 15 min, and it was full of little strings.