I used a blue chalkoner to just quilt the spine of a feather. That blue got stitched right into the quilt. Unluckily for me, it was a customer quilt. She washed it about 4 times...still a faint blue there. It was for her son and she said he would never notice if she didnt' tell him. I won't use that to mark a quilt again. I mostly freehand or use pantos, but I have used a grey/silver chalk pencil with good luck.