I have washed quilts and I just block then to dry and they come out nice and flat. I wash gently (fill the machine with water and colour catchers) hand agitate (so I can keep an eye on everything) spin and remove. If everything looks good, I pop it in the dryer for a little while and take it out when still damp. I take it into the spare room and block it on the carpet nice and flat. I close the door and mention for no one to go in until the quilt is dry. (usually overnight)