I learned the very hard way about pre-washing fabrics. In 2008 I was making a blooming nine-patch for my sister. I completed it but it had not returned from the long armer when she passed away. Months later when I could function and think about it, I asked my children if they wanted to draw straws for it. Simultaneously they asked me to give it to Nancy's best friend. About the time I was wrapping it to ship, I realized I had not washed the red fabric in the very center of the quilt (probably the only piece of real red in the thing). So I wrote a very long letter about why the quilt was hers, and asked her to never wash it! Now, I don't store any fabric in my stash until it is washed. Not only is washed fabric good for the chemo patients for which I make most of my quilts, it doesn't have a chemically smell when I iron. If you are washing fat quarters I found that if you unfold and stack the fq's together, it works great if you pin on all four corners and in the middle with a safety pin. That way they don't get twisted in the washer. I unpin before I throw in the dryer. I wash all my fabrics on hot water with regular detergent.