will those blue marks come off once it is washed? (Hope that makes sense)
Well, that depends on how old the blocks are. I have a quilt on my bed that is at least 30+ years old that my dear aunt made and it is washed often, and the blue marks are still there. But, I believe that the newer blue markings are made to wash out. So, it would depend on the age of the blocks. My quilt has "blue" markings - the newer ones are more of a "turquoise" color. HTH