Should I prewash my fabric?
Many quilters wonder whether they should pre-wash their fabrics before using it to make their quilt or use it just as it comes from the quilt store. There are certainly a lot of discussion points on both sides.
Allergies: The most important reason for washing your fabrics is if you are allergic to the chemicals manufacturers add to the fabrics. Many people are. This allergy causes many kinds of reactions that often go undetected by the quilter. The symptoms can be anything from itchy/burning/tearing eyes, sneezing and even to the extent of wheezing. If you have any of these symptoms, ask yourself if it is your fabrics causing this.
The main reason to pre-wash is to remove the sizing (chemicals). Why do the manufacturers add sizing? This is to reduce wrinkles in the fabric. Sizing makes it a little stiffer to use, which in most cases is a good thing. Some quilters wash the sizing out then spray starch the fabric to stiffen it again. I sometimes wonder if there is any advantage to this.
Shrinking and color bleeds: If you use low quality cotton fabrics, it is advisable to wash your fabrics to prevent shrinking and color bleeds. Most high quality cottons are not known to do this; however low quality cotton fabrics cannot be trusted. In my 25 years of quilting, I've made over 100 quilts and have only had one dye bleed which was in my early quilting days when I used a solid hand-dyed fabric. Colorfast has greatly improved since then. I have not had a problem with shrinking in patchwork fabrics, but know it can certainly be a problem if using cotton denims or like fabrics. Cotton battings can also shrink so I prefer to use a cotton blend batting to prevent this.
Workshops: One reason for not washing fabric is if you happen to be doing a workshop in store or guild, and find you need or want to purchase fabric for the class project. There is really no way to prepare the fabric to use in time without losing valuable class time. Another problem can exist if you like to participate in round robin quilts, some quilters use pre-washed fabrics while others do not. It is preferable to always use one or the other rather than a mixture of both.
Accuracy: As a quilter, I do not wash my fabrics, as I prefer to work with the slightly stiffer textile. Most importantly, I find my cutting, quarter inch seams and quilting is much more accurate with less movement in the fabrics. I do not have a reaction to the chemicals so I really find no need to pre-wash and it saves me valuable time as well. As a traveling teacher, I also find the washing inconvenient.
Suggestions: My suggestion is that you should not use a mix of washed and unwashed fabrics in a quilt and my advice is for you to determine whether you should pre-wash your fabrics or not taking all the points we have discussed into consideration.