An excerpt from Rotary Cut Applique with the Leaves Galore Templates.
Fabric choices for Fusible Applique:
You can use any type of quality cotton fabric for fusible appliqué but my favorite appliqué fabrics are batiks. I prefer batiks because I do a lot of raw-edge fusible appliqué. Loosely woven cottons will fray more than tightly woven cottons. Batiks are typically made with a higher quality, more tightly woven base fabric making fraying less of an issue. I use batiks wherever I can especially for raw edge fusible appliqué.
When I am drawn to a fun printed cotton fabric for my quilt I try to use only high quality printed cottons. Printed cloth is only colored on the surface of the fibers. If you cut the fibers there is a white core. With raw edge fusible appliqué, you might see that white core along the edges of the cut patch. When using prints I generally use a decorative stitch, such as the buttonhole or satin stitch, around the edges of the appliqué to enclose the cut edge of the fabric.
To prewash or not to prewash?
I prewash my fabrics. Period.
Finishing chemicals on the surface of the fabric can interfere with the bond of your fusible. I also do not want to take the chance of my fabric colors running or seams puckering because of uneven shrinkage. The recipient of your quilt may put your finished quilt through the washer and dryer so it is best to be sure your fabrics have already been machine washed and dried. Primarily, I do not want my fusible to misbehave. Your quilts will last a lifetime or more so take time now to prewash and you will never be sorry.
No fabric enters my sewing room without prewashing. As soon as I get back from the quilt shop, I trim the corners of the fabrics with scissors, separate by color (light and dark) and run two loads through the washing machine. If I have very small pieces or really deep rich colors that may run, I swish them in the sink with a dab of hand soap or dish soap. Rinse until you can see the water is clear. Next, I run all fabrics through the clothes drier on a hot cycle, remove when damp and press. I don’t use any form of starch or sizing when pressing. Use only a spray bottle with water to get out all the wrinkles as this will ensure the best bond possible. Now I know that everything in my fabric stash is washed and pressed and I can jump right in and start cutting my next quilt!