Last year, I started pre-washing all of my fabrics. The reason I do this is because knit fabrics tend to shrink a lot once you wash them. So I would rather pre-shrink the fabric myself, than have an item shrink on a customer. Also, the dyes in some fabrics will bleed, and I would rather find that out in the beginning! I use an all natural laundry detergent that is biodegradable and doesn’t have any perfumes or dyes. The largest fabric pieces I get are no more than 10-15 yards, so putting them in my washing machine isn’t a problem. Now this won’t work if you need to shrink fabric that is a hundred yards long. In that case, there are ways to draft the patterns to allow for shrinkage after they are sewn. You have to test a square of the fabric by washing it and calculating what percentage of shrinkage occurred on the straight grain and the cross grain, and then factor that into your pattern. Since I use so many different fabrics, that’s probably not something I would want to do, so pre-washing is the best option for me.