Pigma pens are the best and as PP have said, wash fabric first and make sure to heat set the ink. Instead of wax paper, I used a few pieces of masking tape on the back of each block to stablize the fabric and it worked well.

How would you 'heat set' the sharpie on the Fabric? I'm still new at quilting, and How would i attach the freezer paper to the fabric to hold it still while signing the quilt..Thanks so very much for any help.. Norma in SC

The micron pigma pens are hard to write with for those not used to them.

I did a wedding quilt for my sister last year. I bought every pen I could find and did many wash tests. I found my favorites at Hobby Lobby. They are Pentel roller gel pens for fabric (red, black, blue). I put freezer paper on the back of the blocks and it was almost just like writing on paper. amazing. I set the ink with a warm iron and it did not fade at all when washed. The lines were fine enough that guests could write whatever they wanted. And, being a little bolder than the lines from the micron pens, they are easier to read.

Good luck!
Suze

And it helps to keep them out of the seam allowance if you make a cardboard template to just place over the block before they start to write. We quilters would know that, but non sewers don't have that perspective.