I have used Pigma pens for many, many years, and would not use anything else. I did try a Sharpie pen ONCE, and it was not acceptable as it spread out onto the label. The method I use is to iron a piece of freezer paper onto the back of the fabric you wish to use for the label, this stabilizes the fabric, write your message, heat set and the freezer paper acts like an applique when sewn onto the back of a quilt. I've had labels on some of my quilts that are 10-15 + years old and still legible.