Just a quick follow up for anyone interested. I just finished hand quilting a baby quilt and marked with a #2 mechanical pencil. Had the top all marked and after beginning to quilt the initial design decided I didn't like how that was going. Out came the quilting. Changed my quilting design and re-marked with the same #2 mechanical pencil. Most of this marking was done on a very light grey, tone on tone fabric. I just washed the quilt - normal permanent press cycle; warm water and Arm & Hammer liquid detergent. Every line is gone. Not a one present. It's now in the dryer - woohoo for me that I can finally gift this thing since the baby is now several months old.
This is my typical experience with the #2 pencil.