Actually, I don't wash mine at the laundromat. I get the newly finished rag quilt thoroughly wet at home, where I know the sink/tub is clean. I don't wash it but take it wet to the laundromat and put it in the dryer without heat and let it tumble. then I have to continually remove the excess lint. When it stops shedding then I put it on low heat and take it home when done.
Funny note: One of my rq's really shed a LOT at the laundromat. A sweet little vietnamese lady was worried I had 'broke' the quilt. There was no easy way to explain the process to it. She saw the quilt before I put it in the dryer. When she saw the finished product I wonder what she thought. Too funny.
ali