I wash mine in cold water in the machine then put in the dryer for about 10 minutes, take it out damp and flatten it with my hands. Keep coming back & smoothing it out every time I think of it. I have used a warm iron sometimes but be careful depending on what batting you used. I usually use something like insulbrite or needlepunch and they have poly in them. But I do find they lay flatter once washed than the cotton battings. HTH