I started using pressure sensitive stabilizer for labels. It's quite heavy so it keeps them very stable, and when done you just remove it. I've done several "memory" type quilts and have provided others fabric squares and markers to write on it, and then incorporated it into the back of the quilt (last one had ten 12" squares that people signed).

I iron my label to freezer paper to stabilize, write it with a Frixion pen so I get the spacing correct and then use a Pigma.
I work at the ironing board so the iron is handy to "erase" if the spacing doesn't work. I just made 3 quilts for great grands and put the name, date of birth made by Nana and signed it. It will be a remembrance so they know who I was.

Sorry, permanent markers, including sharpies are not as permanent as you might think. As everyone else says, Pigma pens are much more permanent. They are available in most pen sections of a store and in art and office stores, too.

Here is an article - very interesting that there is no one right answer
http://quiltingdigest.com/which-perm...hXCcstWRoQbOBw

Pigma pens work great, I use them on my labels without any problems. Sharpie permanent pens will bleed when used on certain fabrics too, Pigma pens will not bleed, or fade with washing.

yes, micron pigma pens are great. i used .05 size for siggy quilts for years. after it drys (quickly) i always heat set even though it doesn't say it is required.

One of the companies that sells quilting stencils has stencils of labels as well as the designs printed on fabric. Then you write on them with info about the quilt.

I make my own label using a "Pentel Arts Gel Roller for Fabric, 1.0mm", heat set it and then wash the quilt later and the label looks as good as it did when I first wrote on it.