Pre-washing any kind of home-washable fabric before you sew is considered best practice. There are a few good reasons one might choose not to pre-wash quilt fabrics, though:
In The Modern Quilt Workshop, Bill Kerr and Weeks Ringle recommend always pre-washing your quilting fabrics. They write:
Over the years we have had even high quality fabrics bleed. Some fabrics shrink at quicker rates than others. One fabric maker told us that imported fabrics are sometimes manufactured using chemicals that are not considered safe in the United States. You’re going to be handling this fabric a lot. Make sure it’s clean.
They add that baby shampoo or laundry soap (I like Charlie’s Soap) is preferable over detergent.
Quilter’s Buzz asked this same question a while back and got numerous responses. Many people make it a practice to wash some fabrics but not others.
These arguments and considerations about pre-washing quilting cotton can be extended to all other washable fabric types.
One thing that bugs me about pre-washing woven fabrics is the raveling. Even when I cut my fabric with pinking shears, there tends to be raveling. I hate dealing with the strangled mess that comes out of the washer and dryer. If you have any tips on avoiding that, please let me know. I’ve pre-washed and line-dried my fabrics by hand before, which circumvented the problem, but it’s not the most convenient option.
I admit that I don’t always pre-wash — sometimes I forget, sometimes I’m too excited to get sewing. What about you — do you pre-wash? Why or why not? If you pre-wash only some of the time, why?