You can use a permanent marker but I managed to get a dot of it on a quilt doing something completely different! On top of a quilt!!?? - yeah, well. Also posted a request for how to remove a Sharpie stain!
Anyway I use Crayola washable markers when I'm ever
close to a quilt!
Great idea and thanks for posting it. Now to a question: What happens if you do use permanent marker? What do you use instead?