I haven't washing W&N in the machine, but it doesn't fall apart when washed by hand. I've prewashed smaller pieces for small quilts. There is a yellow tinge to the water after soaking for 20 minutes. I put the pieces in the dryer and they come out great! I've also air dried the batting for 24 hours. Don't do this with Fairfield 80/20 cotton batting however. It really separates in the dryer. I haven't tried this with any other batting.