I prewash all my fabric in at least warm water. Why? Because I want all the bleeding, shrinking, and possible fading to happen before I invest a huge amount of time cutting it and making it into a quilt. And really, I suspect any quilt that leaves my door will be going into a washer with warm or hot water in its future. I have no control of how the owner will care for it. So, I try to make sure it's toughened up a bit and won't self destruct once it leaves my house:>