Hi craftybut,
Just had this "conversation" about guide lines with Mary on topic
http://www.quiltingboard.com/posts/list/15/10288.page
This was her following remark:
Ellen, it wasn't a pencil. It was chalk pounce. I have used the white chalk pounce before and it comes off when you iron it. I like it a lot, but the blue chalk is supposed to come off with a wet rag and it didn't.
I use the mark B gone washable pen and it works great and does come right out when you spritz it with water.
Mary
Good luck to you.. I too am needing guidence !
Ellen